SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0337 PM CST Mon Dec 16 2024 Valid 181200Z - 241200Z The upper-level pattern will be characterized by amplified ridging in the West with broad troughing in the East. Shortwave troughs are expected to progress through parts of the central and eastern U.S. through the rest of this week. Model guidance suggests the western ridge will break down this weekend into early next week. With the more progressive pattern east of the Divide, surface high pressure and colder air is expected to filter into the these areas. Fire weather concerns for most areas will be minimal. Some areas of stronger downslope winds are possible in the central High Plains vicinity as the shortwave troughs move through. Given the colder temperatures, it is not clear how much fire weather concern will develop, but fuels in that region remain dry enough to support increased risk at least on a localized basis. Moderately strong high pressure in the Great Basin will drive offshore winds across parts of southern California. Upper-level wind support will be notably lacking for this event. How low RH will be, especially on Wednesday morning, is also uncertain. With winds through the typical Santa Ana corridors peaking Wednesday morning, the current thinking is that there will be a few hours of critical fire weather as RH begins decrease with daytime heating. Winds are expected to diminish during the afternoon/evening. ..Wendt.. 12/16/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0200 PM CST Mon Dec 16 2024 Valid 162000Z - 171200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE ARK-LA-TEX AND LOWER TO MID MISSISSIPPI VALLEY... ...SUMMARY... Isolated strong to severe thunderstorms with mainly a damaging wind threat may occur today across parts of the ArkLaTex into western Tennessee and vicinity. Some hail may also occur. ...20Z Update... The previous forecast remains on track. Only minor adjustments to the lines have been made for this Day 1 outlook update. A cold front, located from north-central Texas to southeast Missouri, will continue to move southeastward. Ahead of the front, a moist airmass with surface dewpoints in the 60s F, will be unstable enough for a few strong storms this afternoon into early evening. Moderate deep-layer shear will support isolated severe storms capable of marginally severe wind gusts and hail. The wind-damage threat will be located from far northeast Texas into western Tennessee. The hail threat will be primarily focused across the Ark-La-Tex where the stronger instability is currently located. ..Broyles.. 12/16/2024 .PREV DISCUSSION... /ISSUED 1028 AM CST Mon Dec 16 2024/ ...Synopsis... The upper trough over the northern Plains and Upper Midwest will move across the Great Lakes today. Related surface cyclone will develop eastward over northern Ontario, with a trailing cold front advancing east-southeastward across parts of the OH Valley, Mid-South, and southern Plains. The western portion of this front will stall and weaken across the ArkLaTex into central TX by this evening. ...ArkLaTex into the Mid-South... Scattered to numerous showers and thunderstorms are ongoing this morning across parts of northern AR into the lower OH Valley, generally along/near the front. Current expectations are for the better forcing associated with the upper trough to remain mostly displaced to the north of the warm sector through the day, with limited low-level convergence along the cold front and modest low-level warm advection persisting. Latest visible satellite imagery also shows low cloud cover remaining prevalent across much of the ArkLaTex and Mid-South/lower MS Valley. These clouds will likely hinder daytime heating to some extent. Modest mid-level lapse rates were also noted on the 12Z soundings at SHV/LZK, with somewhat better lapse rates aloft at FWD. Even with these limitations regarding forcing and instability, most guidance continues to show around 500-1000 J/kg of MLCAPE along/ahead of the cold front from northeast TX into AR and western TN by mid afternoon. A gradual uptick in convective coverage and intensity should occur through the afternoon across these areas, with modest but sufficient deep-layer shear (25-35 kt) for some updraft organization. Most 12Z HREF guidance shows small clusters developing and spreading east-southeastward through the early evening. Even though low-level lapse rates will probably remain poor due to the limited daytime heating, there still appears to be enough of a signal to support inclusion of a Marginal Risk, mainly for isolated damaging winds. Some hail may also occur across northeast TX into AR, where greater instability should be present. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0200 PM CST Mon Dec 16 2024 Valid 162000Z - 171200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE ARK-LA-TEX AND LOWER TO MID MISSISSIPPI VALLEY... ...SUMMARY... Isolated strong to severe thunderstorms with mainly a damaging wind threat may occur today across parts of the ArkLaTex into western Tennessee and vicinity. Some hail may also occur. ...20Z Update... The previous forecast remains on track. Only minor adjustments to the lines have been made for this Day 1 outlook update. A cold front, located from north-central Texas to southeast Missouri, will continue to move southeastward. Ahead of the front, a moist airmass with surface dewpoints in the 60s F, will be unstable enough for a few strong storms this afternoon into early evening. Moderate deep-layer shear will support isolated severe storms capable of marginally severe wind gusts and hail. The wind-damage threat will be located from far northeast Texas into western Tennessee. The hail threat will be primarily focused across the Ark-La-Tex where the stronger instability is currently located. ..Broyles.. 12/16/2024 .PREV DISCUSSION... /ISSUED 1028 AM CST Mon Dec 16 2024/ ...Synopsis... The upper trough over the northern Plains and Upper Midwest will move across the Great Lakes today. Related surface cyclone will develop eastward over northern Ontario, with a trailing cold front advancing east-southeastward across parts of the OH Valley, Mid-South, and southern Plains. The western portion of this front will stall and weaken across the ArkLaTex into central TX by this evening. ...ArkLaTex into the Mid-South... Scattered to numerous showers and thunderstorms are ongoing this morning across parts of northern AR into the lower OH Valley, generally along/near the front. Current expectations are for the better forcing associated with the upper trough to remain mostly displaced to the north of the warm sector through the day, with limited low-level convergence along the cold front and modest low-level warm advection persisting. Latest visible satellite imagery also shows low cloud cover remaining prevalent across much of the ArkLaTex and Mid-South/lower MS Valley. These clouds will likely hinder daytime heating to some extent. Modest mid-level lapse rates were also noted on the 12Z soundings at SHV/LZK, with somewhat better lapse rates aloft at FWD. Even with these limitations regarding forcing and instability, most guidance continues to show around 500-1000 J/kg of MLCAPE along/ahead of the cold front from northeast TX into AR and western TN by mid afternoon. A gradual uptick in convective coverage and intensity should occur through the afternoon across these areas, with modest but sufficient deep-layer shear (25-35 kt) for some updraft organization. Most 12Z HREF guidance shows small clusters developing and spreading east-southeastward through the early evening. Even though low-level lapse rates will probably remain poor due to the limited daytime heating, there still appears to be enough of a signal to support inclusion of a Marginal Risk, mainly for isolated damaging winds. Some hail may also occur across northeast TX into AR, where greater instability should be present. Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0129 PM CST Mon Dec 16 2024 Valid 181200Z - 191200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Thunderstorms are possible from the lower Ohio Valley southwest into northeast/central Texas early on Wednesday and across the Southeast, Carolinas, and Florida Wednesday afternoon and evening. ...Synopsis... An upper trough will migrate across the eastern half of the CONUS on Wednesday. Boundary-layer moisture will remain modest across the southeast U.S., ahead of a southeast-advancing cold front extending from southern OH southwest to western TN and then central TX Wednesday morning. Isolated showers and thunderstorms are likely to be ongoing along the front at the beginning of the period. This activity will likely be elevated and just to the cool side of the surface front. Instability is expected to be very weak with southeast extent into the TN and Lower MS Valley, and morning thunderstorms will likely diminish in coverage as the front moves southeast. Severe thunderstorms are unlikely given limited instability and modest vertical shear. Additional thunderstorms are possible across Florida and coastal Georgia where persistent easterly flow will continue to advect somewhat richer low-level moisture inland. In addition to this activity, isolated to scattered thunderstorms are possible across Georgia and the Carolinas as isentropic ascent increases with a modest low-level jet response ahead of the approaching mid-level trough. Predictability remains low with this potential as the mid-level vorticity maximum will trail well behind the cold front. Weak upper-level support combined with relatively weak isentropic ascent is the primary limiting factor for severe weather potential across Georgia and the Carolinas Wednesday afternoon/evening. ..Bentley.. 12/16/2024 Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0129 PM CST Mon Dec 16 2024 Valid 181200Z - 191200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Thunderstorms are possible from the lower Ohio Valley southwest into northeast/central Texas early on Wednesday and across the Southeast, Carolinas, and Florida Wednesday afternoon and evening. ...Synopsis... An upper trough will migrate across the eastern half of the CONUS on Wednesday. Boundary-layer moisture will remain modest across the southeast U.S., ahead of a southeast-advancing cold front extending from southern OH southwest to western TN and then central TX Wednesday morning. Isolated showers and thunderstorms are likely to be ongoing along the front at the beginning of the period. This activity will likely be elevated and just to the cool side of the surface front. Instability is expected to be very weak with southeast extent into the TN and Lower MS Valley, and morning thunderstorms will likely diminish in coverage as the front moves southeast. Severe thunderstorms are unlikely given limited instability and modest vertical shear. Additional thunderstorms are possible across Florida and coastal Georgia where persistent easterly flow will continue to advect somewhat richer low-level moisture inland. In addition to this activity, isolated to scattered thunderstorms are possible across Georgia and the Carolinas as isentropic ascent increases with a modest low-level jet response ahead of the approaching mid-level trough. Predictability remains low with this potential as the mid-level vorticity maximum will trail well behind the cold front. Weak upper-level support combined with relatively weak isentropic ascent is the primary limiting factor for severe weather potential across Georgia and the Carolinas Wednesday afternoon/evening. ..Bentley.. 12/16/2024 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0117 PM CST Mon Dec 16 2024 Valid 171200Z - 181200Z Minimal changes were made to the outlook to account for recent guidance. Available high-resolution guidance continues to suggest fairly low probability of sustained critical conditions on Tuesday. The 12Z HRRR is the lone piece of guidance with more aggressive RH reductions Tuesday night. Even so, there is some potential for near-critical to locally critical fire weather briefly during Tuesday afternoon and again late Tuesday night into Wednesday morning. The most likely area for these conditions will be portions of the Santa Clara River Valley and Oxnard Plain. Trends in guidance will continue to be monitored for potential need of critical highlights. ..Wendt.. 12/16/2024 .PREV DISCUSSION... /ISSUED 0150 AM CST Mon Dec 16 2024/ ...Synopsis... Quasi zonal mid-level flow is expected to quickly amplify as ridging develops over the Western US D2/Tues. In the wake of a cold front moving across the central US the day prior, surface high pressure will quickly build over the Great Basin. The high pressure will allow for moderate offshore winds and elevated to near-critical fire-weather concerns over portions of southern CA. ...Southern California... As high pressure intensifies behind the cold front across the Great Basin and interior West, moderate offshore flow is expected to develop D2/Tues into D3/Wed. Santa Ana winds of 15-25 mph will overlap with low RH values of 10-20% across parts of Los Angeles and Ventura counties for several hours. Elevated to near-critical fire-weather conditions appear likely amid dry fuels across portions of southern CA, particularly overnight D2/Tues into D3/Wed. Some uncertainty remains regarding the strength of the winds and minimum RH values in the absence of stronger upper-level support. The best overlap of strong winds and low RH is expected late D2/Tues into early D3/Wed morning. However, if winds trend stronger and earlier as some guidance suggests, critical highlights may be needed sooner. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0117 PM CST Mon Dec 16 2024 Valid 171200Z - 181200Z Minimal changes were made to the outlook to account for recent guidance. Available high-resolution guidance continues to suggest fairly low probability of sustained critical conditions on Tuesday. The 12Z HRRR is the lone piece of guidance with more aggressive RH reductions Tuesday night. Even so, there is some potential for near-critical to locally critical fire weather briefly during Tuesday afternoon and again late Tuesday night into Wednesday morning. The most likely area for these conditions will be portions of the Santa Clara River Valley and Oxnard Plain. Trends in guidance will continue to be monitored for potential need of critical highlights. ..Wendt.. 12/16/2024 .PREV DISCUSSION... /ISSUED 0150 AM CST Mon Dec 16 2024/ ...Synopsis... Quasi zonal mid-level flow is expected to quickly amplify as ridging develops over the Western US D2/Tues. In the wake of a cold front moving across the central US the day prior, surface high pressure will quickly build over the Great Basin. The high pressure will allow for moderate offshore winds and elevated to near-critical fire-weather concerns over portions of southern CA. ...Southern California... As high pressure intensifies behind the cold front across the Great Basin and interior West, moderate offshore flow is expected to develop D2/Tues into D3/Wed. Santa Ana winds of 15-25 mph will overlap with low RH values of 10-20% across parts of Los Angeles and Ventura counties for several hours. Elevated to near-critical fire-weather conditions appear likely amid dry fuels across portions of southern CA, particularly overnight D2/Tues into D3/Wed. Some uncertainty remains regarding the strength of the winds and minimum RH values in the absence of stronger upper-level support. The best overlap of strong winds and low RH is expected late D2/Tues into early D3/Wed morning. However, if winds trend stronger and earlier as some guidance suggests, critical highlights may be needed sooner. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

MD 2270 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR FROM NORTHEAST ARKANSAS ACROSS THE MISSOURI BOOTHEEL AND TOWARD THE OHIO RIVER
Mesoscale Discussion 2270 NWS Storm Prediction Center Norman OK 1042 AM CST Mon Dec 16 2024 Areas affected...from northeast Arkansas across the Missouri Bootheel and toward the Ohio River Concerning...Severe potential...Watch unlikely Valid 161642Z - 161915Z Probability of Watch Issuance...5 percent SUMMARY...We are monitoring convective trends along the immediate cold front from far northeast Arkansas into western Kentucky. DISCUSSION...A cold front currently extends from southwest IN toward the MO Bootheel and into northern AR, with higher reflectivities within a currently low-topped convective line. Southwest surface winds continue to slowly bring relative warmth northward, with minimal instability currently. VWPs show 0-1 km SRH of 200-300 m2/s2, with the strongest values over northern areas. Lightning activity as well as higher echo tops currently exist over northern AR and into the MO Bootheel where instability is more favorable. With time, gradual destabilization within the narrow pre-frontal zone, combined with low-level convergence, could result in a marginal severe risk. This risk is clearly conditional, but a small overlapping area of sufficient instability and favorable low-level shear cold result in a brief/weak tornado or localized damaging wind threat. At this time, a watch it not anticipated. ..Jewell/Gleason.. 12/16/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...PAH...MEG...LZK... LAT...LON 37688814 37898778 37868748 37658743 37118787 36598831 36028920 35798997 35579128 35659172 35889192 36059185 36329062 36588976 37328860 37688814 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1115 AM CST Mon Dec 16 2024 Valid 171200Z - 181200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Thunderstorms are expected from the southern Plains to the Lower Ohio and Tennessee Valley vicinities and across Florida on Tuesday. Severe-thunderstorm chances are low at this time. ...Synopsis... A mid-level jet streak across the Northwest early on Tuesday will start to dig southeast toward the central Plains and sharpen the mid-level trough by Tuesday night. As this occurs, a weak surface low will develop across eastern Colorado and move into the Lower Ohio Valley by the end of the period. A surface front associated with this area of low pressure will accelerate southeast, particularly after 06Z and end up somewhere from Memphis to Waco by 12Z Wednesday. ...ArkLatex into central Arkansas... Despite broad, weak isentropic ascent through the day, only isolated thunderstorm activity is expected from east Texas into the Ozarks due to neutral heights aloft. However, thunderstorm activity is expected to increase after 06Z as the mid-level trough strengthens and approaches the southern Plains/ArkLaTex and a surface front becomes better defined and accelerates southeast. Forecast soundings show moderate instability (1000-1500 J/kg MUCAPE) and lapse rates (~7 C/km) from southern Arkansas to the ArkLaTex. However, the stronger flow will remain mostly across northern Arkansas into the Ohio Valley. Therefore, shear will be relatively weak where thunderstorm activity is most likely along the front from 06Z to 12Z. This will likely result in loosely organized storms which will likely be undercut by the advancing cold front. While isolated hail or a wind gust or two cannot be ruled out, severe weather probabilities remain low. ...Florida... Scattered to widespread thunderstorms are expected across much of the Florida Peninsula as 1200-1500 J/kg MLCAPE develops during peak heating. Shear will be mostly less than 20 knots which should limit storm organization. However, moderate instability and scattered to widespread storm development could result in some small hail or gusty winds. Overall, severe thunderstorms are not expected. ..Bentley.. 12/16/2024 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1115 AM CST Mon Dec 16 2024 Valid 171200Z - 181200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Thunderstorms are expected from the southern Plains to the Lower Ohio and Tennessee Valley vicinities and across Florida on Tuesday. Severe-thunderstorm chances are low at this time. ...Synopsis... A mid-level jet streak across the Northwest early on Tuesday will start to dig southeast toward the central Plains and sharpen the mid-level trough by Tuesday night. As this occurs, a weak surface low will develop across eastern Colorado and move into the Lower Ohio Valley by the end of the period. A surface front associated with this area of low pressure will accelerate southeast, particularly after 06Z and end up somewhere from Memphis to Waco by 12Z Wednesday. ...ArkLatex into central Arkansas... Despite broad, weak isentropic ascent through the day, only isolated thunderstorm activity is expected from east Texas into the Ozarks due to neutral heights aloft. However, thunderstorm activity is expected to increase after 06Z as the mid-level trough strengthens and approaches the southern Plains/ArkLaTex and a surface front becomes better defined and accelerates southeast. Forecast soundings show moderate instability (1000-1500 J/kg MUCAPE) and lapse rates (~7 C/km) from southern Arkansas to the ArkLaTex. However, the stronger flow will remain mostly across northern Arkansas into the Ohio Valley. Therefore, shear will be relatively weak where thunderstorm activity is most likely along the front from 06Z to 12Z. This will likely result in loosely organized storms which will likely be undercut by the advancing cold front. While isolated hail or a wind gust or two cannot be ruled out, severe weather probabilities remain low. ...Florida... Scattered to widespread thunderstorms are expected across much of the Florida Peninsula as 1200-1500 J/kg MLCAPE develops during peak heating. Shear will be mostly less than 20 knots which should limit storm organization. However, moderate instability and scattered to widespread storm development could result in some small hail or gusty winds. Overall, severe thunderstorms are not expected. ..Bentley.. 12/16/2024 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1044 AM CST Mon Dec 16 2024 Valid 161700Z - 171200Z ...NO CRITICAL AREAS... No changes to the ongoing forecast. ..Wendt.. 12/16/2024 .PREV DISCUSSION... /ISSUED 0147 AM CST Mon Dec 16 2024/ ...Synopsis... Fire-weather concerns across the CONUS are minimal. A cold front trailing a strong low in southern Canada will cross the central US, allowing a much cooler air mass to settle over the western US and Rockies. Despite strong mid-level flow supporting downslope winds, poor overlap of strong winds and low humidity is expected outside of brief gusty offshore winds in southern CA. Otherwise, precipitation ahead of the front and from the prior day will augment fuels such that little or no fire-weather risk is expected. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1044 AM CST Mon Dec 16 2024 Valid 161700Z - 171200Z ...NO CRITICAL AREAS... No changes to the ongoing forecast. ..Wendt.. 12/16/2024 .PREV DISCUSSION... /ISSUED 0147 AM CST Mon Dec 16 2024/ ...Synopsis... Fire-weather concerns across the CONUS are minimal. A cold front trailing a strong low in southern Canada will cross the central US, allowing a much cooler air mass to settle over the western US and Rockies. Despite strong mid-level flow supporting downslope winds, poor overlap of strong winds and low humidity is expected outside of brief gusty offshore winds in southern CA. Otherwise, precipitation ahead of the front and from the prior day will augment fuels such that little or no fire-weather risk is expected. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1028 AM CST Mon Dec 16 2024 Valid 161630Z - 171200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF NORTHEAST TEXAS INTO ARKANSAS AND WESTERN TENNESSEE... ...SUMMARY... Isolated strong to severe thunderstorms with mainly a damaging wind threat may occur today across parts of the ArkLaTex into western Tennessee and vicinity. Some hail may also occur. ...Synopsis... The upper trough over the northern Plains and Upper Midwest will move across the Great Lakes today. Related surface cyclone will develop eastward over northern Ontario, with a trailing cold front advancing east-southeastward across parts of the OH Valley, Mid-South, and southern Plains. The western portion of this front will stall and weaken across the ArkLaTex into central TX by this evening. ...ArkLaTex into the Mid-South... Scattered to numerous showers and thunderstorms are ongoing this morning across parts of northern AR into the lower OH Valley, generally along/near the front. Current expectations are for the better forcing associated with the upper trough to remain mostly displaced to the north of the warm sector through the day, with limited low-level convergence along the cold front and modest low-level warm advection persisting. Latest visible satellite imagery also shows low cloud cover remaining prevalent across much of the ArkLaTex and Mid-South/lower MS Valley. These clouds will likely hinder daytime heating to some extent. Modest mid-level lapse rates were also noted on the 12Z soundings at SHV/LZK, with somewhat better lapse rates aloft at FWD. Even with these limitations regarding forcing and instability, most guidance continues to show around 500-1000 J/kg of MLCAPE along/ahead of the cold front from northeast TX into AR and western TN by mid afternoon. A gradual uptick in convective coverage and intensity should occur through the afternoon across these areas, with modest but sufficient deep-layer shear (25-35 kt) for some updraft organization. Most 12Z HREF guidance shows small clusters developing and spreading east-southeastward through the early evening. Even though low-level lapse rates will probably remain poor due to the limited daytime heating, there still appears to be enough of a signal to support inclusion of a Marginal Risk, mainly for isolated damaging winds. Some hail may also occur across northeast TX into AR, where greater instability should be present. ..Gleason/Squitieri.. 12/16/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1028 AM CST Mon Dec 16 2024 Valid 161630Z - 171200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF NORTHEAST TEXAS INTO ARKANSAS AND WESTERN TENNESSEE... ...SUMMARY... Isolated strong to severe thunderstorms with mainly a damaging wind threat may occur today across parts of the ArkLaTex into western Tennessee and vicinity. Some hail may also occur. ...Synopsis... The upper trough over the northern Plains and Upper Midwest will move across the Great Lakes today. Related surface cyclone will develop eastward over northern Ontario, with a trailing cold front advancing east-southeastward across parts of the OH Valley, Mid-South, and southern Plains. The western portion of this front will stall and weaken across the ArkLaTex into central TX by this evening. ...ArkLaTex into the Mid-South... Scattered to numerous showers and thunderstorms are ongoing this morning across parts of northern AR into the lower OH Valley, generally along/near the front. Current expectations are for the better forcing associated with the upper trough to remain mostly displaced to the north of the warm sector through the day, with limited low-level convergence along the cold front and modest low-level warm advection persisting. Latest visible satellite imagery also shows low cloud cover remaining prevalent across much of the ArkLaTex and Mid-South/lower MS Valley. These clouds will likely hinder daytime heating to some extent. Modest mid-level lapse rates were also noted on the 12Z soundings at SHV/LZK, with somewhat better lapse rates aloft at FWD. Even with these limitations regarding forcing and instability, most guidance continues to show around 500-1000 J/kg of MLCAPE along/ahead of the cold front from northeast TX into AR and western TN by mid afternoon. A gradual uptick in convective coverage and intensity should occur through the afternoon across these areas, with modest but sufficient deep-layer shear (25-35 kt) for some updraft organization. Most 12Z HREF guidance shows small clusters developing and spreading east-southeastward through the early evening. Even though low-level lapse rates will probably remain poor due to the limited daytime heating, there still appears to be enough of a signal to support inclusion of a Marginal Risk, mainly for isolated damaging winds. Some hail may also occur across northeast TX into AR, where greater instability should be present. ..Gleason/Squitieri.. 12/16/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0624 AM CST Mon Dec 16 2024 Valid 161300Z - 171200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected through tonight. ...Synopsis/Discussion... A progressive mid/upper-level pattern will persist, with the most important feature being a trough now apparent in moisture-channel imagery from a low over southeastern MB, across western MN, eastern NE, central KS, and the TX Panhandle. The main/northern part of this trough is forecast to weaken and move across the Upper Great Lakes today. A weaker, positively tilted, basal vorticity banner will move eastward from the TX Panhandle across much of OK today, and more slowly moving eastward over northwest TX. By 00Z, this lobe should weaken and extend from the Ozarks to southern OK and the Permian Basin, then become diffuse and perhaps dissipate overnight. As that occurs, a surface cold front -- analyzed at 11Z from eastern IA across southwestern MO, central/southwestern OK and northwest TX -- should move eastward/southeastward by 00Z to near a TOL-EVV-DYR- LIT-DAL-6R6 line. Overnight, the southern part of the front will move slowly southeastward then become quasistationary, reaching a position across northern parts of AL/MS/LA, northeast/north-central TX and the Hill Country. Episodic, widely scattered thunderstorms in bands and clusters are possible near the front, becoming isolated to widely scattered in the warm sector. A few strong thunderstorms may develop this afternoon from the Arklatex into the Mid-South, near time of peak diurnally driven buoyancy. This activity will be within the warm-advection/moisture- transport conveyor, and along/ahead of the surface cold front. A narrow corridor of prefrontal MLCAPE should range from about 2000 J/kg in northeast TX, where heating and moisture will be greatest, to around 1000 J/kg in eastern AR. However, during the surface warming/destabilization peak window, surface flow will be veering and remaining weak, due to the shift of the mid/upper trough and related large-scale lift and mass response away from the area. This will act both to shrink hodographs and weaken frontal convergence with time. Given these offsetting factors, and the increasing dominance of the unfavorable ones with time during the afternoon, severe probabilities appear too low and conditional for an outlook area at this time. ..Edwards/Goss.. 12/16/2024 Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0347 AM CST Mon Dec 16 2024 Valid 191200Z - 241200Z ...DISCUSSION... Medium range guidance is in fairly good agreement that an amplified but progressive upper level pattern will overspread the CONUS during the Day 4-8 period. A shortwave trough over the northern Plains early on Day 4/Thu will deepen and spread east over the eastern half of the CONUS through Day 6 or 7/Sat or Sun. Meanwhile, an amplified upper ridge will build over the western states and spread east into the Plains during this same time period. Spread among guidance increases around Day 6-8/Sat-Mon, but still indicates that another upper trough will emerge over the Plains and Midwest late in the period. A surface cold front will move south and east into the Gulf of Mexico and offshore the Atlantic coast on Thursday. This will clear out any lingering boundary-layer moisture and persistent offshore trajectories will mostly preclude much thunderstorm potential for most of the forecast period. The exception may be on Day 7-8/Sun-Mon as lee troughing allow for southeasterly flow to return across the western Gulf and TX, bringing modest moisture northward across southern/central TX. Nevertheless, severe-thunderstorm potential appears low throughout the forecast period. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0347 AM CST Mon Dec 16 2024 Valid 191200Z - 241200Z ...DISCUSSION... Medium range guidance is in fairly good agreement that an amplified but progressive upper level pattern will overspread the CONUS during the Day 4-8 period. A shortwave trough over the northern Plains early on Day 4/Thu will deepen and spread east over the eastern half of the CONUS through Day 6 or 7/Sat or Sun. Meanwhile, an amplified upper ridge will build over the western states and spread east into the Plains during this same time period. Spread among guidance increases around Day 6-8/Sat-Mon, but still indicates that another upper trough will emerge over the Plains and Midwest late in the period. A surface cold front will move south and east into the Gulf of Mexico and offshore the Atlantic coast on Thursday. This will clear out any lingering boundary-layer moisture and persistent offshore trajectories will mostly preclude much thunderstorm potential for most of the forecast period. The exception may be on Day 7-8/Sun-Mon as lee troughing allow for southeasterly flow to return across the western Gulf and TX, bringing modest moisture northward across southern/central TX. Nevertheless, severe-thunderstorm potential appears low throughout the forecast period. Read more

SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0203 AM CST Mon Dec 16 2024 Valid 181200Z - 191200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Thunderstorms are possible from the lower Ohio Valley southwest into northeast/central Texas, as well as across the Florida Peninsula and Georgia coast on Wednesday. Severe thunderstorms are not expected. ...Synopsis... An upper trough will migrate across the eastern half of the CONUS on Wednesday. Boundary-layer moisture will remain modest across the southeast U.S., ahead of a southeast-advancing cold front extending from southern OH southwest to western TN and then central TX Wednesday morning. Isolated showers and thunderstorms are likely to be ongoing along the front at the beginning of the period. This activity will likely be elevated and just to the cool side of the surface front. Instability is expected to be very weak with southeast extent into the TN and Lower MS Valley, and morning thunderstorms will likely diminish in coverage as the front moves southeast. Severe thunderstorms are unlikely given limited instability and modest vertical shear. Additional thunderstorms are expected across the FL Peninsula and perhaps the GA coast. Low-level easterly flow will continue to maintain somewhat richer low-level moisture to the east of a surface inverted trough and in a separate regime from the approaching upper trough and surface front to the west. This will aid in modest destabilization through peak heating. Weak vertical shear will limit storm organization, and severe storms appear unlikely at this time. ..Leitman.. 12/16/2024 Read more

SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0203 AM CST Mon Dec 16 2024 Valid 181200Z - 191200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Thunderstorms are possible from the lower Ohio Valley southwest into northeast/central Texas, as well as across the Florida Peninsula and Georgia coast on Wednesday. Severe thunderstorms are not expected. ...Synopsis... An upper trough will migrate across the eastern half of the CONUS on Wednesday. Boundary-layer moisture will remain modest across the southeast U.S., ahead of a southeast-advancing cold front extending from southern OH southwest to western TN and then central TX Wednesday morning. Isolated showers and thunderstorms are likely to be ongoing along the front at the beginning of the period. This activity will likely be elevated and just to the cool side of the surface front. Instability is expected to be very weak with southeast extent into the TN and Lower MS Valley, and morning thunderstorms will likely diminish in coverage as the front moves southeast. Severe thunderstorms are unlikely given limited instability and modest vertical shear. Additional thunderstorms are expected across the FL Peninsula and perhaps the GA coast. Low-level easterly flow will continue to maintain somewhat richer low-level moisture to the east of a surface inverted trough and in a separate regime from the approaching upper trough and surface front to the west. This will aid in modest destabilization through peak heating. Weak vertical shear will limit storm organization, and severe storms appear unlikely at this time. ..Leitman.. 12/16/2024 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0150 AM CST Mon Dec 16 2024 Valid 171200Z - 181200Z ...Synopsis... Quasi zonal mid-level flow is expected to quickly amplify as ridging develops over the Western US D2/Tues. In the wake of a cold front moving across the central US the day prior, surface high pressure will quickly build over the Great Basin. The high pressure will allow for moderate offshore winds and elevated to near-critical fire-weather concerns over portions of southern CA. ...Southern California... As high pressure intensifies behind the cold front across the Great Basin and interior West, moderate offshore flow is expected to develop D2/Tues into D3/Wed. Santa Ana winds of 15-25 mph will overlap with low RH values of 10-20% across parts of Los Angeles and Ventura counties for several hours. Elevated to near-critical fire-weather conditions appear likely amid dry fuels across portions of southern CA, particularly overnight D2/Tues into D3/Wed. Some uncertainty remains regarding the strength of the winds and minimum RH values in the absence of stronger upper-level support. The best overlap of strong winds and low RH is expected late D2/Tues into early D3/Wed morning. However, if winds trend stronger and earlier as some guidance suggests, critical highlights may be needed sooner. ..Lyons.. 12/16/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more