MD 0046 CONCERNING WINTER MIXED PRECIPITATION FOR PORTIONS OF THE MIDDLE AND UPPER TEXAS COAST VICINITY
Mesoscale Discussion 0046 NWS Storm Prediction Center Norman OK 0256 AM CST Tue Jan 21 2025 Areas affected...Portions of the Middle and Upper Texas Coast Vicinity Concerning...Winter mixed precipitation Valid 210856Z - 211330Z SUMMARY...A mix of sleet and light freezing rain/drizzle will remain possible through daybreak. A gradual shift to snow (from north to south) will also occur with time. DISCUSSION...A mix of winter precipitation continues within and north the Middle/Upper Texas Coast regions. Based on reported precipitation and model sounding data, a mixture of sleet and lighter freezing rain/drizzle is most likely. Given the presence of steep lapse rates at cloud top (both noted in regional observed soundings and model soundings), some convective elements are possible and would be more efficient sleet producers. With time, additional large-scale ascent will cool the atmospheric column such that precipitation should continue to switch to all snow by daybreak and beyond. Should freezing rain/drizzle linger, this is most likely to be nearer the coast where the cold air may be shallow enough to support it. ..Wendt.. 01/21/2025 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...HGX...CRP...EWX... LAT...LON 28049692 27649732 27679765 27819799 28169817 29139788 29569711 30089523 30039480 29439466 28049692 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0649 AM CST Tue Jan 21 2025 Valid 211300Z - 221200Z ...NO THUNDERSTORM AREAS FORECAST... ...SUMMARY... The risk for thunderstorms appears negligible across the U.S. today through tonight. A large surface high dominates the weather across the CONUS today, with cold, dry, and stable conditions preventing thunderstorms. A strengthening surface low off the Gulf coast may provide isolated thunderstorms offshore later today and tonight, but lightning activity is expected to remain well south of the coast. ..Hart/Wendt.. 01/21/2025 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0649 AM CST Tue Jan 21 2025 Valid 211300Z - 221200Z ...NO THUNDERSTORM AREAS FORECAST... ...SUMMARY... The risk for thunderstorms appears negligible across the U.S. today through tonight. A large surface high dominates the weather across the CONUS today, with cold, dry, and stable conditions preventing thunderstorms. A strengthening surface low off the Gulf coast may provide isolated thunderstorms offshore later today and tonight, but lightning activity is expected to remain well south of the coast. ..Hart/Wendt.. 01/21/2025 Read more

MD 0045 CONCERNING HEAVY SNOW FOR PORTIONS OF FAR WESTERN NEW YORK
Mesoscale Discussion 0045 NWS Storm Prediction Center Norman OK 1030 PM CST Mon Jan 20 2025 Areas affected...portions of far western New York Concerning...Heavy snow Valid 210430Z - 211030Z SUMMARY...At least 2-3 inch/hour snowfall rates should continue past sunrise with an intense lake-effect snow band. DISCUSSION...MRMS mosaic and KTYX radar imagery show an intense, steady-state lake-effect snow band persisting across Jefferson and Lewis Counties in far western NY. This snow-band is benefiting from an optimal fetch of moisture off of Lake Ontario, where 8+ C/km 0-3 km lapse rates are in place. As such, convective snowfall within this lake-effect band should persist past sunrise, as shown by the latest high-resolution guidance consensus. Furthermore, given the convective nature of the band, and degree of saturation in the dendritic growth zone, snowfall rates at least in the 2-3 inch/hour range are expected through the remainder of tonight. ..Squitieri.. 01/21/2025 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...BUF... LAT...LON 43977634 44027567 43947519 43697514 43547540 43587581 43617612 43647630 43977634 Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0302 AM CST Tue Jan 21 2025 Valid 241200Z - 291200Z ...DISCUSSION... An amplified and progressive upper trough will move quickly from the MS Valley to the East Coast on Friday/D4, with zonal flow developing behind this system. High pressure will follow, maintaining dry offshore winds across the Southeast. Models remain in relatively good agreement with the large-scale pattern through the weekend, depicting a positive-tilt upper trough over the southwestern states. A broad fetch of west/southwest flow aloft is forecast to extend across the southern Plains and into much of the East, with the deep upper low over eastern Canada. Sufficient instability is forecast to develop across parts of southern and eastern TX into the lower MS Valley Saturday/D5 Night into Sunday/D6. Given the antecedent cool air at the surface, substantial clouds and precipitation appear likely, reducing overall destabilization and severe potential. Models diverge around Monday/D7, with uncertainly regarding whether another wave will develop into the northern Plains and Great Lakes as disturbances rotate around the large-scale low. To the west, the trough/low over the Southwest may eventually eject east, but timing for this is uncertain as well with low predictability at this time frame. In any case, severe potential is forecast to be low through the period. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0302 AM CST Tue Jan 21 2025 Valid 241200Z - 291200Z ...DISCUSSION... An amplified and progressive upper trough will move quickly from the MS Valley to the East Coast on Friday/D4, with zonal flow developing behind this system. High pressure will follow, maintaining dry offshore winds across the Southeast. Models remain in relatively good agreement with the large-scale pattern through the weekend, depicting a positive-tilt upper trough over the southwestern states. A broad fetch of west/southwest flow aloft is forecast to extend across the southern Plains and into much of the East, with the deep upper low over eastern Canada. Sufficient instability is forecast to develop across parts of southern and eastern TX into the lower MS Valley Saturday/D5 Night into Sunday/D6. Given the antecedent cool air at the surface, substantial clouds and precipitation appear likely, reducing overall destabilization and severe potential. Models diverge around Monday/D7, with uncertainly regarding whether another wave will develop into the northern Plains and Great Lakes as disturbances rotate around the large-scale low. To the west, the trough/low over the Southwest may eventually eject east, but timing for this is uncertain as well with low predictability at this time frame. In any case, severe potential is forecast to be low through the period. Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0157 AM CST Tue Jan 21 2025 Valid 221200Z - 231200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF SOUTHERN CALIFORNIA... ...Synopsis... A surface pressure gradient will persist across southern California, with some strengthening of the gradient likely by late Wednesday afternoon as another in a series of mid-level troughs overspread the Great Basin tomorrow (Wednesday). Another day of offshore flow capable of supporting rapid wildfire spread is expected. By afternoon peak heating, widespread sustained 20-30 mph wind speeds are likely, along with RH dropping to at least the 10-15 percent range. Locally higher wind speeds/gusts are also likely in terrain-favoring areas. Anywhere from the Ventura Valley region to the Laguna Mountains may experience the aforementioned meteorological surface conditions, necessitating the introduction of Critical fire weather highlights this outlook. ..Squitieri.. 01/21/2025 ...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 0156 AM CST Tue Jan 21 2025 Valid 211200Z - 221200Z ...EXTREMELY CRITICAL FIRE WEATHER AREA FOR PORTIONS OF THE VENTURA VALLEY TO THE SAN BERNARDINO MOUNTAINS IN SOUTHERN CALIFORNIA... ...EXTREMELY CRITICAL FIRE WEATHER AREA FOR PORTIONS OF THE SAN JACINTO TO LAGUNA MOUNTAIN RANGES... ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF SOUTHERN CALIFORNIA... ...Synopsis... A mid-level trough across the southwest U.S. will rapidly track eastward toward the Southeast while surface high pressure persists over the Great Basin through the period. Strong offshore flow will persist from the Ventura Valley to the Laguna Mountains, with widespread 20-30 mph sustained winds and 10 percent RH expected during the day into early Wednesday morning, warranting the maintenance of Critical highlights across much of the far southern California shoreline. Furthermore, the latest high-resolution guidance consensus shows sustained winds exceeding 40 mph, coinciding with single-digit RH, from the Ventura Valley to the San Bernardino Mountains, as well as the San Jacinto to Laguna Mountain ranges, where Extremely Critical highlights were maintained. The best chance for Extremely Critical conditions will be during the morning into early afternoon hours. ..Squitieri.. 01/21/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0117 AM CST Tue Jan 21 2025 Valid 231200Z - 241200Z ...NO THUNDERSTORM AREAS FORECAST... ...SUMMARY... Thunderstorms are not forecast on Thursday. ...Synopsis... A cool and stable pattern will persist on Thursday across the CONUS with an expansive upper trough over much of the central states and into the Great Lakes. This trough may amplify as it becomes more progressive and moves into the MS Valley by 12Z Friday. A strongly cyclonic speed max will exist along the northern Gulf Coast, with cooling aloft to the north. At the surface, another installment of high pressure will push into the Gulf of Mexico, with further drying. Any appreciable low-level moisture will remain east of the FL Peninsula, and as such, thunderstorms are not forecast. ..Jewell.. 01/21/2025 Read more

MD 0043 CONCERNING WINTER MIXED PRECIPITATION FOR PORTIONS OF SOUTH INTO SOUTHEAST AND EASTERN TEXAS
Mesoscale Discussion 0043 NWS Storm Prediction Center Norman OK 1000 PM CST Mon Jan 20 2025 Areas affected...portions of south into southeast and eastern Texas Concerning...Winter mixed precipitation Valid 210400Z - 210800Z SUMMARY...Wintry precipitation rates should increase through tonight across southeastern portions of Texas, with sleet and freezing rain accumulations likely to continue. DISCUSSION...700 mb WAA continues to increase atop a sub-freezing airmass over southeastern TX as a positively tilted mid-level trough glances the region to the north. Meanwhile, the dry low-levels support wet-bulb temperatures well below freezing given ample evaporative cooling/sublimation potential. Over the next couple of hours, continued cooling of the surface-850 mb layer, due to both 925 mb CAA and evaporative cooling, should support an increased potential for wintry precipitation (as evident based on recent reports of ice accretion and sleet accumulations). The greatest near-term potential for freezing rain/ice accretion will be along a zone roughly from Wilson to Tyler Counties, where surface observations show surface temperatures already cooled below 32 F. Latest high-resolution guidance shows sleet/freezing rates peaking sometime after 06Z, including over portions of deep-south TX. With time, at least moderate snowfall rates may eventually be observed closer to the southeast TX coastline. ..Squitieri.. 01/21/2025 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LCH...SHV...HGX...CRP...EWX... LAT...LON 28789686 27639811 27479862 28629842 29729812 30359727 30899592 31199473 31259398 30999377 30489386 29879437 29819506 28789686 Read more

MD 0044 CONCERNING HEAVY SNOW FOR PORTIONS OF FAR WESTERN NEW YORK
Mesoscale Discussion 0044 NWS Storm Prediction Center Norman OK 1016 PM CST Mon Jan 20 2025 Areas affected...portions of far western New York Concerning...Heavy snow Valid 210416Z - 210815Z SUMMARY...Heavy lake-effect snow should continue into the early morning hours, with 3 inch/hour intermittent snowfall rates likely. DISCUSSION...The lake-effect snow-band has taken a more southwest-to-northeast orientation over the past hour or so, with heavy snow recently reported as far south as the Dunkirk Airport. 04Z mesoanalysis shows increased boundary-layer convergence and moistening along a northern Chautaugua to Erie County line, which will support continued heavy snowfall rates within the main band. Snowfall accumulations over very short time periods via reports suggest that near 3 inch/hour snowfall rates may be occurring with this snow band. With the 04Z mesoanalysis showing 7.5 C/km 0-3 km lapse rates present over water (where a long moisture fetch is in place), 2-3 inch/hour snowfall rates may continue into the early morning hours, as also suggested by latest high-resolution guidance consensus. ..Squitieri.. 01/21/2025 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...BUF... LAT...LON 42467965 42677916 42857882 42937844 42827827 42577845 42407890 42337923 42357944 42357954 42467965 Read more

SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1048 PM CST Mon Jan 20 2025 Valid 221200Z - 231200Z ...NO THUNDERSTORM AREAS FORECAST... ...SUMMARY... Thunderstorms are not expected on Wednesday. ...Synopsis... A large upper trough will remain over all but the westernmost CONUS on Wednesday, with a leading trough exiting the East Coast early in the day. At that time, high pressure will firmly be in place over the East, with strong north winds over the Gulf of Mexico and western Atlantic. A weak surface low may develop along the front over the Bahamas, but low-level moisture and instability is forecast to remain off the FL Peninsula. Behind this system, another upper trough will develop out of the Rockies and into the central states, with another strong area of high pressure centered over the Intermountain West into Thursday morning. The cool and/or stable air mass over land will thus maintain little if any chance of thunderstorms through the period. ..Jewell.. 01/21/2025 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1046 PM CST Mon Jan 20 2025 Valid 211200Z - 221200Z ...NO THUNDERSTORM AREAS FORECAST... ...SUMMARY... The risk for thunderstorms appears negligible across the U.S. today through tonight. ...Discussion... Ridging to the north of the blocking mid-level high centered over the mid-latitude eastern Pacific is rebuilding, as an initially suppressing short wave perturbation progresses inland across British Columbia. The latter feature is forecast to dig through the northern U.S. Rockies and adjacent Great Plains by 12Z Wednesday, reinforcing large-scale troughing now encompassing much of central and eastern North America. As this occurs, a pair of initially digging downstream short wave perturbations will be forced east-northeastward, into and through strong, confluent flow between a prominent mid-level ridge centered over the subtropical western Atlantic and a broad cyclonic circulation centered over the far northeastern Canadian provinces. Although down slope flow may contribute to moderating temperatures across the northern and central Great Plains, seasonably cold air associated with surface ridging entrenched across much of the southern Great Plains through Atlantic Seaboard will generally be maintained. It appears that the shallow leading edge of this cold air mass will remain south and east of the Florida Peninsula and Keys, with little in the way of surface frontal wave development across the west central through southeastern Gulf of Mexico due to lack of mid/upper support. ...Northwestern Gulf coast... In the presence of steepening mid-level lapse rates associated with differential thermal advection, it still appears that elevated moisture return will contribute to weak destabilization (rooted in the 800-700 mb layer) as far northwest as upper Texas/Louisiana coastal areas by 12-15Z this morning. This probably will provide support for a period of increasing convective development, with thermodynamic profiles possibly become conducive to at least some lightning production before diminishing by early afternoon. There remains substantive spread concerning this potential, however, and thunderstorm probabilities will be maintained at less than 10 percent, based on objective calibrated guidance from both the NCEP SREF and HREF. ..Kerr.. 01/21/2025 Read more

MD 0042 CONCERNING HEAVY SNOW FOR PORTIONS OF FAR WESTERN NEW YORK
Mesoscale Discussion 0042 NWS Storm Prediction Center Norman OK 0713 PM CST Mon Jan 20 2025 Areas affected...portions of far western New York Concerning...Heavy snow Valid 210113Z - 210415Z SUMMARY...Heavy snow should develop through tonight with an approaching lake-effect snow band. 2-3 inch/hour snowfall rates are likely, at least on an intermittent basis. DISCUSSION...While heavy snow has recently been reported by the KART ASOS, the ongoing snow-band should shift several miles southward over the next couple of hours, as indicated by KTYX regional radar data. The CWQP surface observation along the Ontario shoreline showed an abrupt wind-shift and brief increase in speed as the snow-band shifted to the south of this location, indicating potential appreciable low-level convergence. The strong convergence associated with the approaching snow-band, amid 8+ C/km 0-3 km lapse rates, suggest that the snowfall is likely associated with low-topped convection. The low-topped convection will benefit from a long fetch of Lake Ontario moisture as low-level flow parallels the lake axis this evening. Heavy lake-effect snow should begin soon, and given convective banding with 90 percent RH in the dendritic growth zone, production efficiency may be high enough to support at least 2 inch/hr snowfall rates, perhaps reaching 3 inches/hr at times. ..Squitieri.. 01/21/2025 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...BUF... LAT...LON 43867632 43927582 43917548 43787548 43697575 43687615 43757627 43867632 Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0647 PM CST Mon Jan 20 2025 Valid 210100Z - 211200Z ...NO THUNDERSTORM AREAS FORECAST... ...SUMMARY... The risk for thunderstorms appears negligible across the U.S. tonight. ...01Z Update... Cold surface ridging has become entrenched across much of the interior U.S. through much of the Gulf Basin and offshore western Atlantic coastal waters. This will become reinforced overnight across the southern Great Plains through middle and southern Atlantic Seaboard, downstream of a pair of digging short wave troughs, where confluent mid-level flow will be maintained to the northwest of a prominent ridge centered over the subtropical western Atlantic. In advance of the southwestern of the two perturbations digging within positively tilted larger scale troughing, currently across the Southwest and adjacent international border vicinity, warm thermal and moisture advection is ongoing above the cold surface-based air across the western Gulf of Mexico into northwestern Gulf coast vicinity. This is supporting increasing precipitation offshore of the lower Texas coast, which is forecast to expand northeastward and eastward across much of the northwestern Gulf/Gulf Coast region by late tonight. Model forecast soundings continue to suggest that elevated destabilization, rooted within the 800-700 mb layer, is possible ahead of developing weak surface troughing as far northwest as the upper Texas coast by 12Z Tuesday. The NAM soundings, in particular, continue to indicate profiles which could become supportive of convection capable of producing lightning. However, based on the objective calibrated guidance of both the NCEP SREF and HREF, probabilities for this still appear less than the minimum 10 percent threshold for a categorical thunder area. ..Kerr.. 01/21/2025 Read more

No watches are valid as of Mon Jan 20 23:46:02 UTC 2025.

MD 0041 CONCERNING HEAVY SNOW FOR PORTIONS OF FAR WESTERN NEW YORK
Mesoscale Discussion 0041 NWS Storm Prediction Center Norman OK 0439 PM CST Mon Jan 20 2025 Areas affected...portions of far western New York Concerning...Heavy snow Valid 202239Z - 210245Z SUMMARY...Instances of heavy lake-effect snow should continue through the evening, with 2 inch/hour snowfall rates possible, especially over Erie County, New York. DISCUSSION...Deep-layer flow (especially closer to the surface) has become more aligned with the long axis of Lake Erie over the past couple of hours given the passing of a weak surface trough. The long fetch of appreciable low-level moisture off of the lake waters will support lake effect snow into the evening hours. 6-7 C/km low-level lapse rates (evident via 22Z mesoanalysis) will support continued heavier snowfall (as was recently observed at the DKK ASOS), with snowfall rates potentially approaching 2 inches/hour at times. ..Squitieri.. 01/20/2025 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...BUF... LAT...LON 42667911 42767897 42817890 42907887 42927861 42777847 42617851 42527878 42517889 42577899 42667911 Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0400 PM CST Mon Jan 20 2025 Valid 221200Z - 281200Z ...Southern California - Days 3-4/Wednesday-Thursday... Within a belt of broad northwesterly flow aloft across the West, an embedded shortwave trough will track southeastward across the Great Basin into the southern Rockies/High Plains. At the same time, an upstream midlevel ridge will build over the eastern Pacific and West Coast. This will favor strengthening surface high pressure over the Intermountain West, forcing a strong offshore pressure gradient across southern CA (LAX-DAG pressure gradient around -5 to -7 mb). Given a very dry air mass in place, critical fire-weather conditions are expected over the wind-prone Santa Ana Corridor surrounding the LA Basin, as well as along the mountains/valleys in San Diego County. Current indications are that this event will peak Day 3/Wednesday night into Day 4/Thursday morning. Thereafter, onshore flow should develop across southern CA, reducing the fire-weather threat through the weekend. ...Southwest into the southern Rockies and High Plains... Dry breezy conditions are expected across the region from Day 5/Friday into the weekend ahead of a large-scale trough. However, any fire-weather concerns should remain fairly localized owing to marginal fuels -- precluding Critical probabilities at this time. ..Weinman.. 01/20/2025 ...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 0152 PM CST Mon Jan 20 2025 Valid 211200Z - 221200Z ...EXTREMELY CRITICAL FIRE WEATHER AREA FOR THE SAN GABRIEL MOUNTAINS WEST TOWARDS THE SANTA MONICA MOUNTAINS AND SANTA SUSANA MOUNTAINS...INCLUDING THE MALIBU COAST... ...EXTREMELY CRITICAL FIRE WEATHER AREA FOR PORTIONS OF THE EASTERN SAN DIEGO FOOTHILLS INTO THE WESTERN SAN JACINTO MOUNTAINS... ...CRITICAL FIRE WEATHER AREA FOR MUCH OF SOUTHERN CALIFORNIA... The previous forecast (see below) remains on track, and only minor adjustments were made to the Day 2/Tuesday outlook. Most noteworthy, the Extremely Critical highlights along the San Jacinto Mountains were expanded slightly northward toward the San Bernardino Mountains in northern Riverside County. The latest high-resolution guidance is in very good agreement here, depicting a gap-flow enhancement to the winds -- favoring several hours of sustained surface winds around 40 mph (with higher gusts) amid single-digit RH. Localized extremely critical conditions are also possible along the Santa Ana Mountains during the morning/early afternoon hours. ..Weinman.. 01/20/2025 .PREV DISCUSSION... /ISSUED 0208 AM CST Mon Jan 20 2025/ ...Synopsis... A strong Santa Ana wind event beginning Monday afternoon will persist well into Tuesday afternoon and evening, resulting in widespread Critical and Extremely Critical fire-weather conditions across much of Southern California. ...Extremely Critical fire-weather conditions for the San Gabriel, Santa Monica, and Santa Susana Mountains... Extremely Critical fire-weather conditions will persist from the Day 1 outlook period (Mon) well into Day 2 (Tues). Sustained winds of 40-45 MPH (gusting 70-100 MPH on mountains, 50-80 MPH in the valleys/coastal regions) with single-digit relative humidity values as low as 2%-5% will be ongoing at the start of the period, subsiding by late Tuesday afternoon/early Tuesday evening. For more details, see the current Day 1 fire-weather outlook. ...Extremely Critical fire-weather conditions for portions of the eastern San Diego foothills into the western San Jacinto Mountains... Confidence has increased in strong, dry offshore flow across far Southern California, particularly portions of the eastern San Diego foothills into the San Jacinto Mountains. Recent 00Z HREF guidance shows ensemble mean sustained surface winds as high as 50-55 MPH, with the ensemble maximum as high as 60 MPH and gusts as high as 80 MPH. Coupled with single-digit relative humidities, this will result in several hours of Extremely Critical fire-weather conditions supportive of rapid wildfire onset and spread, subsiding by late Tuesday evening into Wednesday morning. ...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 0152 PM CST Mon Jan 20 2025 Valid 211200Z - 221200Z ...EXTREMELY CRITICAL FIRE WEATHER AREA FOR THE SAN GABRIEL MOUNTAINS WEST TOWARDS THE SANTA MONICA MOUNTAINS AND SANTA SUSANA MOUNTAINS...INCLUDING THE MALIBU COAST... ...EXTREMELY CRITICAL FIRE WEATHER AREA FOR PORTIONS OF THE EASTERN SAN DIEGO FOOTHILLS INTO THE WESTERN SAN JACINTO MOUNTAINS... ...CRITICAL FIRE WEATHER AREA FOR MUCH OF SOUTHERN CALIFORNIA... The previous forecast (see below) remains on track, and only minor adjustments were made to the Day 2/Tuesday outlook. Most noteworthy, the Extremely Critical highlights along the San Jacinto Mountains were expanded slightly northward toward the San Bernardino Mountains in northern Riverside County. The latest high-resolution guidance is in very good agreement here, depicting a gap-flow enhancement to the winds -- favoring several hours of sustained surface winds around 40 mph (with higher gusts) amid single-digit RH. Localized extremely critical conditions are also possible along the Santa Ana Mountains during the morning/early afternoon hours. ..Weinman.. 01/20/2025 .PREV DISCUSSION... /ISSUED 0208 AM CST Mon Jan 20 2025/ ...Synopsis... A strong Santa Ana wind event beginning Monday afternoon will persist well into Tuesday afternoon and evening, resulting in widespread Critical and Extremely Critical fire-weather conditions across much of Southern California. ...Extremely Critical fire-weather conditions for the San Gabriel, Santa Monica, and Santa Susana Mountains... Extremely Critical fire-weather conditions will persist from the Day 1 outlook period (Mon) well into Day 2 (Tues). Sustained winds of 40-45 MPH (gusting 70-100 MPH on mountains, 50-80 MPH in the valleys/coastal regions) with single-digit relative humidity values as low as 2%-5% will be ongoing at the start of the period, subsiding by late Tuesday afternoon/early Tuesday evening. For more details, see the current Day 1 fire-weather outlook. ...Extremely Critical fire-weather conditions for portions of the eastern San Diego foothills into the western San Jacinto Mountains... Confidence has increased in strong, dry offshore flow across far Southern California, particularly portions of the eastern San Diego foothills into the San Jacinto Mountains. Recent 00Z HREF guidance shows ensemble mean sustained surface winds as high as 50-55 MPH, with the ensemble maximum as high as 60 MPH and gusts as high as 80 MPH. Coupled with single-digit relative humidities, this will result in several hours of Extremely Critical fire-weather conditions supportive of rapid wildfire onset and spread, subsiding by late Tuesday evening into Wednesday morning. ...Please see www.spc.noaa.gov/fire for graphic product... Read more