SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1145 PM CST Wed Dec 18 2024 Valid 201200Z - 211200Z ...NO THUNDERSTORM AREAS FORECAST... ...SUMMARY... Thunderstorms are not expected across the Lower 48 on Friday. ...Synopsis... An upper shortwave trough developing southeast over the northern/central Plains to the to the Mid-MS Valley will reinforce mean upper troughing over the eastern half of the CONUS on Friday. Strong surface high pressure will overspread the central U.S. while a cold front develops far south into the Gulf and offshore the Atlantic coast. This will leave a dry and stable airmass over much of the CONUS, and thunderstorm chances will be low. ..Leitman.. 12/19/2024 Read more

SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1145 PM CST Wed Dec 18 2024 Valid 201200Z - 211200Z ...NO THUNDERSTORM AREAS FORECAST... ...SUMMARY... Thunderstorms are not expected across the Lower 48 on Friday. ...Synopsis... An upper shortwave trough developing southeast over the northern/central Plains to the to the Mid-MS Valley will reinforce mean upper troughing over the eastern half of the CONUS on Friday. Strong surface high pressure will overspread the central U.S. while a cold front develops far south into the Gulf and offshore the Atlantic coast. This will leave a dry and stable airmass over much of the CONUS, and thunderstorm chances will be low. ..Leitman.. 12/19/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1048 PM CST Wed Dec 18 2024 Valid 191200Z - 201200Z ...NO THUNDERSTORM AREAS FORECAST... ...SUMMARY... Thunderstorms are not expected today through tonight. ...Discussion... A quiescent pattern for thunderstorms is expected over the CONUS today through tonight. A weakening cold front will become increasingly ill-defined as it settles southward over the FL Peninsula. A few, low-topped showers might form along it this afternoon. But the lack of adequate convergence and weak mid-level lapse rates should preclude thunderstorm development over land. Elsewhere, scant elevated buoyancy may accompany a progressive shortwave trough as it tracks from the northern Great Plains to the OH Valley. With a cold thermodynamic profile, this minimal buoyancy would emanate from sub-freezing parcels rooted near 700 mb. A few flashes might occur along the southern envelope of winter precipitation in the MN/IA to WI/IL border vicinity this morning/afternoon. This could produce a very isolated thunder threat, but probabilities appear below 10 percent. ..Grams/Lyons.. 12/19/2024 Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0646 PM CST Wed Dec 18 2024 Valid 190100Z - 191200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Thunderstorms will largely diminish across the Southeast tonight. ...Southeast... Isolated thunderstorms persist across parts of the Carolinas into the FL Panhandle, and separately over the south FL Peninsula. Within a weakly buoyant warm-moist sector ahead of this activity, overall convective potential will generally diminish. This will occur more rapidly overnight as large-scale ascent weakens/shifts off the South Atlantic Coast. Thunderstorms will be relegated to the Gulf Stream during the early morning. ..Grams.. 12/19/2024 Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0317 PM CST Wed Dec 18 2024 Valid 201200Z - 261200Z Upper-level ridging over the West will continue to shift eastward and eventually lose amplitude as it moves into the Plains this weekend. Shortwave troughs are expected to move through the northern/central Plains late this weekend into early next week. By the middle of next week, guidance shows agreement that a shortwave trough will move into the Southwest and eject into the southern Plains around Wednesday/Thursday. The overall fire weather concern during the period is likely to be low on account of cooler temperatures and/or light winds. Some locally elevated conditions could occur in the central High Plains with the passage of the shortwave troughs. The feature to watch will be the forecast trough moving into the southern Plains. Areas of eastern New Mexico and western Texas have received little rainfall recently. Some increase in fire weather concern is possible those areas depending on the timing of the trough. ..Wendt.. 12/18/2024 ...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 0145 PM CST Wed Dec 18 2024 Valid 182000Z - 191200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are unlikely through the rest of the period. Scattered thunderstorms will continue across portions of the Southeast into the Mid-Atlantic. ...20z... The severe risk has diminished across middle and eastern Tennessee as of 20z, prompting the removal of the remaining Marginal risk area. Thunderstorm activity will continue across the Southeast and into the Mid-Atlantic along the front this afternoon. See previous discussion for more information. ..Thornton/Gleason.. 12/18/2024 .PREV DISCUSSION... /ISSUED 1028 AM CST Wed Dec 18 2024/ ...Middle/Eastern Tennessee and Vicinity... A line of convection along/near a cold front will continue to progress steadily eastward across parts of eastern KY, middle/eastern TN and northern AL. This activity is generally outpacing greater low-level moisture to its south, and related instability. Isolated strong to damaging winds still appear possible for a couple more hours while the line can maintain its intensity, even though boundary-layer instability and lapse rates aloft remain rather weak. But, expectations are for the line to weaken quickly by early/mid afternoon as it encounters the higher terrain of the Appalachians and an even less favorable thermodynamic environment. ...Remainder of Southeast into the Southern Mid-Atlantic... Continued low-level warm/moist advection will occur today ahead of an eastward-moving upper trough and related surface cold front. While a conditionally somewhat favorable environment to support organized severe convection should exist across parts of the Southeast into the Carolinas ahead of the front, limited low-level convergence and poor lapse rates/instability should tend to hinder thunderstorm development for most areas. Convection does appear more probable across parts of central/south FL this afternoon and evening, but weak shear should limit severe potential. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0145 PM CST Wed Dec 18 2024 Valid 182000Z - 191200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are unlikely through the rest of the period. Scattered thunderstorms will continue across portions of the Southeast into the Mid-Atlantic. ...20z... The severe risk has diminished across middle and eastern Tennessee as of 20z, prompting the removal of the remaining Marginal risk area. Thunderstorm activity will continue across the Southeast and into the Mid-Atlantic along the front this afternoon. See previous discussion for more information. ..Thornton/Gleason.. 12/18/2024 .PREV DISCUSSION... /ISSUED 1028 AM CST Wed Dec 18 2024/ ...Middle/Eastern Tennessee and Vicinity... A line of convection along/near a cold front will continue to progress steadily eastward across parts of eastern KY, middle/eastern TN and northern AL. This activity is generally outpacing greater low-level moisture to its south, and related instability. Isolated strong to damaging winds still appear possible for a couple more hours while the line can maintain its intensity, even though boundary-layer instability and lapse rates aloft remain rather weak. But, expectations are for the line to weaken quickly by early/mid afternoon as it encounters the higher terrain of the Appalachians and an even less favorable thermodynamic environment. ...Remainder of Southeast into the Southern Mid-Atlantic... Continued low-level warm/moist advection will occur today ahead of an eastward-moving upper trough and related surface cold front. While a conditionally somewhat favorable environment to support organized severe convection should exist across parts of the Southeast into the Carolinas ahead of the front, limited low-level convergence and poor lapse rates/instability should tend to hinder thunderstorm development for most areas. Convection does appear more probable across parts of central/south FL this afternoon and evening, but weak shear should limit severe potential. Read more

No Mesoscale Discussions are in effect as of Wed Dec 18 19:50:02 UTC 2024.

No watches are valid as of Wed Dec 18 19:50:02 UTC 2024.

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0131 PM CST Wed Dec 18 2024 Valid 191200Z - 201200Z ...NO CRITICAL AREAS... No changes to the ongoing forecast. With a potent shortwave trough move southeastward into the central Plains, a deepening surface low will promote winds of 20-30 mph over parts of western/central Nebraska. Winds will support a locally elevated fire weather threat, but marginal temperatures/RH should limit greater concerns. ..Wendt.. 12/18/2024 .PREV DISCUSSION... /ISSUED 0158 AM CST Wed Dec 18 2024/ ...Synopsis... Mid-level ridging over the western US is forecast to move eastward Thursday as the overall upper-air pattern becomes more amplified. At the surface, high pressure over the Great Basin will move into the Rockies. Aside from some residual offshore flow over parts of southern CA, widespread fire-weather concerns are not expected. ...Southern CA... Offshore winds are expected to gradually diminish overnight D1/Wednesday and into early D2/Thursday, as high pressure over the Great Basin shifts eastward. While winds should generally weaken, some lingering, locally elevated fire-weather conditions may continue in the typical Santa Ana mountains/foothills through the afternoon. Limited in spatial coverage and duration, fire-weather concerns are not expected to be widespread. ...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 0131 PM CST Wed Dec 18 2024 Valid 191200Z - 201200Z ...NO CRITICAL AREAS... No changes to the ongoing forecast. With a potent shortwave trough move southeastward into the central Plains, a deepening surface low will promote winds of 20-30 mph over parts of western/central Nebraska. Winds will support a locally elevated fire weather threat, but marginal temperatures/RH should limit greater concerns. ..Wendt.. 12/18/2024 .PREV DISCUSSION... /ISSUED 0158 AM CST Wed Dec 18 2024/ ...Synopsis... Mid-level ridging over the western US is forecast to move eastward Thursday as the overall upper-air pattern becomes more amplified. At the surface, high pressure over the Great Basin will move into the Rockies. Aside from some residual offshore flow over parts of southern CA, widespread fire-weather concerns are not expected. ...Southern CA... Offshore winds are expected to gradually diminish overnight D1/Wednesday and into early D2/Thursday, as high pressure over the Great Basin shifts eastward. While winds should generally weaken, some lingering, locally elevated fire-weather conditions may continue in the typical Santa Ana mountains/foothills through the afternoon. Limited in spatial coverage and duration, fire-weather concerns are not expected to be widespread. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 1257 PM CST Wed Dec 18 2024 Valid 201200Z - 211200Z ...NO THUNDERSTORM AREAS FORECAST... ...SUMMARY... Thunderstorms are not expected across the Lower 48 on Friday. ...Synopsis... A large-scale mid/upper-level trough will persist across much of the central/eastern CONUS on Friday, as a significant embedded shortwave moves from the Ohio Valley vicinity towards the Carolinas and eventually offshore. A reinforcing cold front attendant to the shortwave trough will move southward across the Gulf of Mexico and Florida Peninsula. Dry/stable conditions and the influence of an expansive post-frontal surface ridge should limit destabilization and thunderstorm potential east of the Rockies. Across the West, a mid/upper-level shortwave trough is forecast to move across the Pacific Northwest early in the day and weaken with time. In its wake, a stronger trough over the eastern Pacific will begin to approach the OR/northern CA coast late Friday night. Convection with sporadic lightning flashes may accompany this stronger shortwave trough and approach near-coastal areas early Saturday morning, but thunderstorm potential is currently expected to remain largely offshore through the end of the period. ..Dean.. 12/18/2024 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1048 AM CST Wed Dec 18 2024 Valid 191200Z - 201200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected on Thursday. ...Synopsis... A broad mid/upper-level trough with multiple embedded shortwaves will remain in place across much of the central/eastern CONUS on Thursday. Within the large-scale trough, one strong shortwave will move eastward off of the New England coast, while another moves southeastward from the Great Plains toward the Ohio Valley and Southeast. A weaker shortwave trough will move across Florida during the morning and early afternoon. Farther west, a low-amplitude mid/upper-level shortwave trough will move across parts of WA/OR during the day. A dearth of low-level moisture and instability should generally limit thunderstorm potential across most of the CONUS. Some convection may linger early in the period near the NC coast, but thunderstorm potential in this area is expected to remain offshore. Otherwise, isolated storm development cannot be ruled out across parts of south FL. ...Parts of Florida... In the wake of a weak frontal passage, very light low-level northerly flow is expected on Thursday across much of the FL Peninsula. Lingering low-level moisture (with dewpoints in the 60s F) will support modest diurnal destabilization. However, despite the presence of the approaching shortwave trough and increasing mid/upper-level flow, there is currently very little signal for deep convection across the peninsula on Thursday, likely resulting from modest to poor midlevel lapse rates and weak to negligible low-level convergence and ascent. A conditional general thunderstorm area has been maintained across parts of south FL, where somewhat stronger heating/destabilization is possible, though confidence in storm development remains low. ..Dean.. 12/18/2024 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1048 AM CST Wed Dec 18 2024 Valid 191200Z - 201200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected on Thursday. ...Synopsis... A broad mid/upper-level trough with multiple embedded shortwaves will remain in place across much of the central/eastern CONUS on Thursday. Within the large-scale trough, one strong shortwave will move eastward off of the New England coast, while another moves southeastward from the Great Plains toward the Ohio Valley and Southeast. A weaker shortwave trough will move across Florida during the morning and early afternoon. Farther west, a low-amplitude mid/upper-level shortwave trough will move across parts of WA/OR during the day. A dearth of low-level moisture and instability should generally limit thunderstorm potential across most of the CONUS. Some convection may linger early in the period near the NC coast, but thunderstorm potential in this area is expected to remain offshore. Otherwise, isolated storm development cannot be ruled out across parts of south FL. ...Parts of Florida... In the wake of a weak frontal passage, very light low-level northerly flow is expected on Thursday across much of the FL Peninsula. Lingering low-level moisture (with dewpoints in the 60s F) will support modest diurnal destabilization. However, despite the presence of the approaching shortwave trough and increasing mid/upper-level flow, there is currently very little signal for deep convection across the peninsula on Thursday, likely resulting from modest to poor midlevel lapse rates and weak to negligible low-level convergence and ascent. A conditional general thunderstorm area has been maintained across parts of south FL, where somewhat stronger heating/destabilization is possible, though confidence in storm development remains low. ..Dean.. 12/18/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1028 AM CST Wed Dec 18 2024 Valid 181630Z - 191200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF MIDDLE/EASTERN TENNESSEE AND NORTHERN ALABAMA... ...SUMMARY... Isolated strong to damaging wind gusts remain possible into early afternoon across parts of the Tennessee Valley region. ...Middle/Eastern Tennessee and Vicinity... A line of convection along/near a cold front will continue to progress steadily eastward across parts of eastern KY, middle/eastern TN and northern AL. This activity is generally outpacing greater low-level moisture to its south, and related instability. Isolated strong to damaging winds still appear possible for a couple more hours while the line can maintain its intensity, even though boundary-layer instability and lapse rates aloft remain rather weak. But, expectations are for the line to weaken quickly by early/mid afternoon as it encounters the higher terrain of the Appalachians and an even less favorable thermodynamic environment. ...Remainder of Southeast into the Southern Mid-Atlantic... Continued low-level warm/moist advection will occur today ahead of an eastward-moving upper trough and related surface cold front. While a conditionally somewhat favorable environment to support organized severe convection should exist across parts of the Southeast into the Carolinas ahead of the front, limited low-level convergence and poor lapse rates/instability should tend to hinder thunderstorm development for most areas. Convection does appear more probable across parts of central/south FL this afternoon and evening, but weak shear should limit severe potential. ..Gleason/Squitieri.. 12/18/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1028 AM CST Wed Dec 18 2024 Valid 181630Z - 191200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF MIDDLE/EASTERN TENNESSEE AND NORTHERN ALABAMA... ...SUMMARY... Isolated strong to damaging wind gusts remain possible into early afternoon across parts of the Tennessee Valley region. ...Middle/Eastern Tennessee and Vicinity... A line of convection along/near a cold front will continue to progress steadily eastward across parts of eastern KY, middle/eastern TN and northern AL. This activity is generally outpacing greater low-level moisture to its south, and related instability. Isolated strong to damaging winds still appear possible for a couple more hours while the line can maintain its intensity, even though boundary-layer instability and lapse rates aloft remain rather weak. But, expectations are for the line to weaken quickly by early/mid afternoon as it encounters the higher terrain of the Appalachians and an even less favorable thermodynamic environment. ...Remainder of Southeast into the Southern Mid-Atlantic... Continued low-level warm/moist advection will occur today ahead of an eastward-moving upper trough and related surface cold front. While a conditionally somewhat favorable environment to support organized severe convection should exist across parts of the Southeast into the Carolinas ahead of the front, limited low-level convergence and poor lapse rates/instability should tend to hinder thunderstorm development for most areas. Convection does appear more probable across parts of central/south FL this afternoon and evening, but weak shear should limit severe potential. ..Gleason/Squitieri.. 12/18/2024 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1029 AM CST Wed Dec 18 2024 Valid 181700Z - 191200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF LOS ANGELES AND VENTURA COUNTIES IN SOUTHERN CALIFORNIA... No changes to the ongoing forecast. Elevated to near-critical fire weather is ongoing in the typical Santa Ana corridors this morning. Given the observed magnitude of the offshore gradient this morning, a few hours of critical fire weather remain possible today as RH falls in conjunction with surface heating. ..Wendt.. 12/18/2024 .PREV DISCUSSION... /ISSUED 0157 AM CST Wed Dec 18 2024/ ...Synopsis... Mid-level ridging over the western US is forecast to intensify through the forecast period, as the overall flow pattern amplifies. Surface high pressure over the Great Basin will continue to build, supporting offshore flow across parts of southern CA. Santa Ana winds, in combination with low RH values, should allow for several hours of elevated to critical fire-weather conditions across southern CA. ...Southern CA... High pressure in the Great Basin will drive offshore winds across parts of southern California early this morning, continuing through the afternoon. With the offshore pressure gradient remaining fairly strong (-4 to -6 mb) through the first half of the day, gusts of 40-50 mph through the terrain-favored corridors and on ridge tops are expected. Several hours of critical fire weather conditions are likely across portions of Los Angeles and Ventura Counties, with RH values below 15%. Winds are expected to slowly diminish during the evening and overnight as the pressure gradient weakens into early D2/Thur. ...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 1029 AM CST Wed Dec 18 2024 Valid 181700Z - 191200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF LOS ANGELES AND VENTURA COUNTIES IN SOUTHERN CALIFORNIA... No changes to the ongoing forecast. Elevated to near-critical fire weather is ongoing in the typical Santa Ana corridors this morning. Given the observed magnitude of the offshore gradient this morning, a few hours of critical fire weather remain possible today as RH falls in conjunction with surface heating. ..Wendt.. 12/18/2024 .PREV DISCUSSION... /ISSUED 0157 AM CST Wed Dec 18 2024/ ...Synopsis... Mid-level ridging over the western US is forecast to intensify through the forecast period, as the overall flow pattern amplifies. Surface high pressure over the Great Basin will continue to build, supporting offshore flow across parts of southern CA. Santa Ana winds, in combination with low RH values, should allow for several hours of elevated to critical fire-weather conditions across southern CA. ...Southern CA... High pressure in the Great Basin will drive offshore winds across parts of southern California early this morning, continuing through the afternoon. With the offshore pressure gradient remaining fairly strong (-4 to -6 mb) through the first half of the day, gusts of 40-50 mph through the terrain-favored corridors and on ridge tops are expected. Several hours of critical fire weather conditions are likely across portions of Los Angeles and Ventura Counties, with RH values below 15%. Winds are expected to slowly diminish during the evening and overnight as the pressure gradient weakens into early D2/Thur. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

MD 2272 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR TENNESSEE VALLEY AREA
Mesoscale Discussion 2272 NWS Storm Prediction Center Norman OK 0554 AM CST Wed Dec 18 2024 Areas affected...Tennessee Valley area Concerning...Severe potential...Watch unlikely Valid 181154Z - 181430Z Probability of Watch Issuance...20 percent SUMMARY...A strong wind gust or two, or even a very brief/weak tornado, will be possible across the Tennessee Valley area this morning as a line of storms progresses across the region. WW issuance is unlikely to be needed. DISCUSSION...Latest radar loop shows a semi-continuous band of thunderstorms advancing across western Kentucky/western Tennessee and the Arklatex region early this morning, near an advancing cold front. The pre-frontal boundary layer is characterized by temperatures in the low 60s, and dewpoints in the mid to upper 50s (Kentucky and most of Tennessee) to the low 60s/northern Mississippi). However, this degree of boundary-layer theta-e remains insufficient to allow truly surface-based convection, with a weak stable layer indicated in the 900 to 950mm layer. Above the weak stable layer, modest elevated CAPE (around 500 J/kg) is indicated -- sufficient for widespread lightning and even vigorous/bowing segments within the line locally. While the slightly elevated nature of the convection should continue to limit overall severe potential, the most organized segments within the line will be capable of producing gusty winds -- perhaps near severe levels locally. Even a very brief/weak tornado cannot be ruled out, near one of the embedded bowing structures. Still, with storms moving quickly through the Tennessee Valley area -- too soon to allow any appreciable pre-convective diurnal heating to occur -- it appears at this time that risk should remain too low to warrant WW consideration. ..Goss/Edwards.. 12/18/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LMK...OHX...HUN...MEG... LAT...LON 34799045 35888833 36718690 36808596 35998599 35508618 34808817 34538948 34539050 34799045 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0651 AM CST Wed Dec 18 2024 Valid 181300Z - 191200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE TENNESSEE VALLEY REGION... ...SUMMARY... Isolated damaging wind gusts and a brief tornado are possible into early afternoon across parts of the Tennessee Valley region. ...Synopsis... A continuing progressive pattern aloft will be dominated by two main shortwave troughs: a trailing perturbation now over the coastal Pacific Northwest, and a positively tilted one apparent in moisture- channel imagery near a DBQ-STJ-P28-DHT axis. The latter will be the main mid/upper-level convective influence this period, as it elongates and tracks to near a PIT-LEX-ELD-GLS line by 00Z. The southern part of the trough is progged to amplify and become less positively tilted as it crosses the Mississippi Delta region tonight, reaching northern GA, eastern AL and the western FL Panhandle by 12Z. At the surface, 11Z analysis showed a cold front across parts of northern/western KY, western TN, southern AR, and northeast/central/ southwest TX. By 00Z, the front should extend from a low over northern NJ southwestward, roughly along the Blue Ridge, then over northern GA to the FL Panhandle. By the end of the period, the cold front should be off all the Atlantic Coast except central FL, extending southwestward to the southern Gulf. ...TN and vicinity... Isolated, damaging to marginally severe gusts and/or a brief tornado are possible into the afternoon, mainly over portions of TN. A near-frontal band of thunderstorms was ongoing from the Arklatex region across the Mid-South, to central KY. Ahead of this activity, a northward-narrowing corridor of 60s F surface dewpoints (and related near-surface-based effective-inflow parcels) was evident, supporting 250-750 J/kg MLCAPE from near MEM to northwest of BNA, where the 12Z sounding still showed a stable boundary layer. See SPC Mesoscale Discussion 2272 for near-term info. Weak, continuing, preconvective theta-e advection, and perhaps a few deg F of cloud-restrained diurnal warming, will offset modest midlevel lapse rates enough to maintain and perhaps slightly increase surface-based buoyancy eastward across TN through early/mid afternoon. Although flow ahead of the QLCS that has not already done so should veer to south-southwest or southwest, enough hodograph enlargement will remain to support around 100-150 J/kg 0-500m SRH and 200-300 J/kg effective SRH, amid 35-45-kt effective-shear magnitudes. As such, the main concern will arise from episodic, embedded BOW/LEWP formations and accompanying mesocirculations. The convective band should outpace the already marginally unstable boundary layer by midafternoon. ..Edwards/Goss.. 12/18/2024 Read more