Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/01/24


Area Forecast Discussion
National Weather Service Billings MT
632 PM MST Wed Jan 31 2024 .UPDATE... A couple more daily records were set today: 62F at both Livingston and Baker, the latter of which marks the warmest January temp in its period of record at the airport (1999-present). Surface trof in central MT is yielding modest gusts at LVM (38 mph at 6pm) and light easterly winds east of Billings. Have adjusted winds up a bit along the foothills, where gusts should stay 40 mph or less. Recent HRRR runs still not showing fog in our east but conceptually localized fog is possible. Current dewpts at Miles City and Baker are in the lower 30s and temps will fall below these values late tonight, w/ clear skies. JKL && .DISCUSSION... Rest of Today through Thursday Night... Prominent upper ridging and downsloping is occurring once again across eastern MT, keeping temperatures very above normal and forecast highs flirting with record territories. WInds are still breezy across south-central MT as a modest pressure gradient still exists across the area. The main change from the last few days is that far Southeast MT will begin to see a light southeast wind tonight and Thursday night. This wind will bring some moisture with it and bring about localized fog, though mainly in river valleys where dewpoint depressions will reduce faster, and on southeast-facing aspects of hills. This southeast wind will allow temperatures to moderate (but only slightly, and they will still be very above normal, just not 60s like the past few days). Lastly, here`s our table of forecasted highs and their current records over the next two days. | Today | Thursday | | Forecast | Record | Forecast | Record | Billings | 62 | 67 | 57 | 68 | Livingston | 62 | 60 | 58 | 60 | Miles City | 52 | 72 | 51 | 61 | Sheridan | 63 | 66 | 57 | 70 | Vertz Friday through Wednesday... This weekend we will see an interesting pattern emerge that will bring about more active weather moving forward. A ridge to the east of us and a low pressure system moving in from the west will eventually create a Rex block over the eastern United States. This pattern will align to bring strong southeast winds over the plains that will transport moisture nearing 250% of normal to our region. Precipitation amounts have come down due to the lack of strong forcing over the region. Chances for 1/2 inch of precipitation are now very low (<15%) across the lower elevations. Higher elevations will see higher amounts thanks to orographic lift. Snowfall amounts for the lower elevations have come down as well as it looks increasingly unlikely that cold air will be able to make its way into the region soon enough to switch precipitation types. When looking at the Ensemble Clusters, it can be seen that the farther north the low is located, the more snow that we are likely to see. However, this solution is only favored by 20% of models at this time. Overall, locations west of Forsyth to Sheridan are the most likely to get snow with these locations seeing a 20-25% chance of seeing 1 inch. Currently, a scenario in which this system starts out as rain on Saturday before slowly transitioning to snow from west to east on Sunday is favored. If precipitation totals continue this lower trend (<0.5 in), overland flooding and ice jams would not be as great of a threat. This is something that will continue to be monitored. The middle of next week will see the potential for another round of precipitation. Ensemble clusters currently depict this as more of a traditional trough coming off the Pacific. Not much is known about the potential evolution of this system at this time. Friday will be the warmest day of the long term with temperatures generally in the 50s. By next week temperatures will settle back into more seasonable temperatures in the low to mid 40s across the region. Torgerson && .AVIATION... Patchy fog reducing visibility is possible (overall low chance) tonight into early Thursday morning from KMLS to KBHK. Otherwise, VFR conditions will prevail over the next 24 hours. Vertz/Arends && .PRELIMINARY POINT TEMP/POPS... Thu Fri Sat Sun Mon Tue Wed ----------------------------------------------------------- BIL 034/059 032/055 035/047 034/041 027/044 028/045 028/041 00/U 00/B 25/R 86/O 21/B 11/B 23/S LVM 035/060 036/055 036/044 031/039 023/044 028/045 028/043 00/U 01/E 48/R 85/S 11/B 12/O 34/S HDN 027/058 025/054 029/048 031/042 025/046 024/047 023/043 00/U 00/B 14/O 87/O 21/B 11/B 23/S MLS 025/052 029/053 030/050 031/043 024/043 023/043 024/041 00/U 00/B 02/R 66/O 31/B 01/B 12/O 4BQ 028/059 034/060 034/052 033/046 027/047 026/048 026/046 00/U 00/B 03/R 66/R 31/B 00/B 12/O BHK 028/056 027/048 030/047 032/045 026/044 023/045 023/043 00/U 00/N 02/R 56/O 41/B 01/B 12/S SHR 028/059 027/056 030/048 029/041 022/045 023/047 023/043 00/U 00/B 25/O 87/O 21/B 00/B 12/O && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...None. WY...None. && $$ weather.gov/billings
Area Forecast Discussion
National Weather Service Corpus Christi TX
548 PM CST Wed Jan 31 2024 ...New AVIATION... .SHORT TERM... (Tonight through Thursday night) Issued at 239 PM CST Wed Jan 31 2024 Key Messages: - There is a medium to high chance (30-60%) of fog across inland portions of South Texas tonight with a better chance (60-85%) Thursday night. - There is a very low chance (<10%) of light rain late tonight into Thursday morning. The axis of an upper level ridge has shifted to the east of S TX in response to a broad trough moving across western Mexico. An embedded short wave ahead of the trough is forecast to move northeast across S TX overnight. The HRRR and NAM indicate light precip developing across the southwestern portion of the CWA late tonight and shifting northeast with the short wave through Thursday morning. Moisture in the mid and upper levels may be sufficient for isolated light rain or sprinkles, as PWATs increase to 1 inch. However, the lower layers between 850-600mb are quite dry. Thus, any precip from the mid/upper levels will likely evaporate before reaching the ground. This will lead to a very low chance (<10%) of precip, therefore, the mention of precip will not be included in the forecast for tonight at this time. The main question continues to be whether or not fog will develop overnight into early Thursday morning. The SREF shows a medium to high probability (30-60%) of visibilities 1SM or less across the eastern Brush Country and western Coastal Plains. However, the cloud deck aloft will inhibit radiational fog from developing. The surface dewpoints are gradually increasing, but so are the min temps. For now, will only mention light patchy fog for these areas for tonight/early Thursday morning. Conditions may be more favorable Thursday night for fog to develop as dewpoints creep into the low 60s, and there will be less cloud cover. The SREF shows a 60% chance across Duval and Jim Wells counties up to an 85% across the Victoria Crossroads of visibilities less than 1SM. The caveat will be winds around 10kts keeping the airmass mixed. Thus, will be going with patchy fog again Thu night, but this could change to include areas of dense fog with later updates if warranted. As for during the day Thursday, generally expecting mostly cloudy skies in the morning, becoming partly cloudy by afternoon as the short wave exits to the northeast. Temperatures will be 2-5 degrees warmer with highs approaching 80 along the Rio Grande Plains. Winds will be S-SE and slightly stronger around 10-15 mph. && .LONG TERM... (Friday through next Tuesday) Issued at 239 PM CST Wed Jan 31 2024 Key Messages: - Marginal risk of severe thunderstorms late afternoon Friday - Rain and thunderstorm chances continue into late Saturday morning - Dry, windy conditions Sunday and Monday could lead to fire weather concerns An increase in moisture continues through the long term ahead of an upper level low and subsequent cold front that will impact the region by Friday. This uptick in moisture could lead to an increased chance of some areas of patchy fog come Friday morning. The low pressure system mentioned above will progress eastward throughout the morning and early afternoon Friday, with PWAT values between 1" and 1.5" just ahead of a cold front moving in by Saturday morning. This will allow for high chances for rain (60-80%) across the Victoria Crossroads and northern portions of the Coastal Bend a medium chance (50-60%) across the remainder of the CWA. The latest deterministic and ensemble guidance points to areas of the Victoria Crossroads receiving anywhere from 0.5" to 1" of rainfall from this system. While flash flooding can`t be ruled out due to the elevated surface moisture from last week`s rain event, chances remain low at this time (5%). Because of this, the Weather Prediction Center has supported the inclusion of a Marginal Risk for excessive rainfall which could lead to localized, minor flooding. The chance for some isolated severe storms is not out of the question either. The Storm Prediction Center placed much of south central Texas in a Marginal Risk for severe thunderstorms for Friday night into Saturday morning, with hail and gusty winds being the primary threats. 0-6 km bulk shear of 30 to 50 knots is favorable, however, instability remains on the lower side. Rain chances come to an end Saturday afternoon and will be followed by dry, windy conditions. The probability for wind gusts over 40 mph on Sunday is high (70-90%) with these gusty conditions continuing over the waters on Monday. This coupled with low relative humidity values around 15-30% could result in both wind advisories and elevated fire weather conditons. However, some uncertainty remains in terms of fire weather conditions being probable due to soil moisture content projected to remain above normal. Though we are expecting a cold front passage, temperatures are not expected to fall too low. Lows on Saturday and Sunday will range in the low-to-mid 50s with highs in the mid 60s to low 70s to end the weekend and start the new week. && .AVIATION... (00Z TAFS) Issued at 541 PM CST Wed Jan 31 2024 Mostly VFR conditions can be expected across area terminals through the cycle. The exception being a brief period between 10-14Z Thursday morning, when patchy fog may develop, restricting visibilities to MVFR levels at ALI/COT/VCT sites. Mid to high level clouds will maintain cloudy to mostly cloudy conditions across the area with a potential return of some low level clouds on Thursday. Otherwise, expect a light southerly wind this evening to become variable early Thursday morning, then increase to around 12 knots by the afternoon. && .MARINE... Issued at 239 PM CST Wed Jan 31 2024 Light onshore winds can be expected tonight, becoming weak to moderate Thursday and Thursday night. Key Messages: - There is a high chance of hazardous navigating conditions for small craft beginning Friday and continuing into early next week. -There is a medium chance of gales Sunday and Monday. Onshore flow increases to strong levels Friday afternoon and night before shifting to offshore behind a cold front Saturday. Offshore flow becomes strong to very strong on Sunday and Monday with gusts to gale force possible. Conditions are expected to begin improving late Monday evening as high pressure builds into the northwest Gulf of Mexico. && .PRELIMINARY POINT TEMPS/POPS... Corpus Christi 55 73 60 76 / 10 10 0 0 Victoria 49 72 56 75 / 0 10 0 10 Laredo 57 78 60 82 / 10 10 0 0 Alice 52 76 57 79 / 10 10 0 0 Rockport 55 68 59 71 / 10 10 0 0 Cotulla 53 77 57 80 / 10 0 0 10 Kingsville 54 75 58 78 / 10 10 0 0 Navy Corpus 59 70 62 71 / 0 10 0 0 && .CRP WATCHES/WARNINGS/ADVISORIES... TX...None. GM...None. && $$ SHORT TERM...TE LONG TERM....KRS AVIATION...ANM/88
Area Forecast Discussion
National Weather Service Quad Cities IA IL
826 PM CST Wed Jan 31 2024 .KEY MESSAGES... - A much warmer than normal pattern will continue into the first week of February. - The overall weather pattern will be fairly quiet the first week of February with systems passing well to the south. && .UPDATE... Issued at 822 PM CST Wed Jan 31 2024 Current satellite and observations do not show any notable fog development in northeast Iowa or nearby. The snow cover has become quite patchy, and I`m somewhat concerned that even the aggressive HRRR runs have now shown far less fog formation toward morning. For now, I`ll keep the headline going, but confidence in widespread dense fog is not very high. && .SHORT TERM /THROUGH TONIGHT/... Issued at 200 PM CST Wed Jan 31 2024 Clouds will continue to slowly clear east of the Mississippi through sunset. The question then is how widespread will any fog development become tonight. With an inversion aloft, melting snow this afternoon will only add more moisture to the lower atmosphere. The signals are there for widespread fog north of highway 20 tonight into Thursday. What is not entirely clear is where will the southern boundary of the more widespread fog be located. Unfortunately this is where any model struggles, especially when the moisture layer is thin. So right now the plan is to hoist fog headlines for the highway 20 corridor from Dubuque on west from midnight until 11 AM Thursday. Confidence on this occurring is in the 40-50 percent range and roughly matches what occurred earlier today in central Iowa. Further south confidence is around 20-25 percent. The potential is there for an expansion of the fog headlines later tonight once observational data shows how the fog is playing out. After the fog lifts late Thursday morning dry but mostly cloudy conditions will be seen as a weak upper level disturbance approaches from the Plains. Temperatures will be warmer than normal but cloud cover will dictate how warm it gets during the day. Temperatures Thursday may approach record highs depending upon cloud cover. Refer to the climate section for specific numbers. && .LONG TERM /THURSDAY THROUGH WEDNESDAY/... Issued at 200 PM CST Wed Jan 31 2024 Thursday night through next Wednesday Assessment...high confidence on much warmer than normal temperatures. Medium to high confidence on dry conditions. The global models develop a blocking pattern over the eastern half of the CONUS through next Wednesday. An upper level high will remain over the Great Lakes and upper Midwest with an upper low in the lower Mississippi Valley. This type of pattern is called a rex block and remains fairly stationary for up to a week at a time. The overall weather pattern has the southern jet being the more active of the two across the CONUS into next week. Thus any systems moving across the country will move under the upper high over the Great Lakes and upper Midwest. The benefit to the immediate area is fairly benign weather for the area. The only unknown over the period will be how warm will it get. With southerly flow pushing moisture into the area the potential is there for clouds to persist with an inversion remaining aloft. Said inversion would also have the potential to allow periods of fog to occur. So while the weather temperature wise will be benign for early February, the potential is there for not much sun to be seen. && .AVIATION /00Z TAFS THROUGH 00Z FRIDAY/... Issued at 518 PM CST Wed Jan 31 2024 Conditions are starting VFR/clear with light southwest winds at all sites tonight. Models are still insistent in showing IFR visibility and clouds developing from north to around I-80 very late tonight, and this could produce minimum VLIFR at CID and DBQ towards 12Z. However, this is not a high confidence situation and for now, I`ve included IFR but not minimum conditions at these terminals. Farther south, they appear to be outside of the fog/cigs threat, but some temporary lowered visibility near 3 miles is possible around sunrise. The poor conditions will be slow to improve if they develop, and IFR may linger much of the morning in the northern sites. && .HYDROLOGY... Issued at 240 PM CST Tue Jan 30 2024 Some rises on area creeks and streams have been observed in the last 48-72 hours, especially across western Illinois. This is due to the recent rainfall and snowmelt. Be prepared for an increase in standing water, especially near creeks and streams. River levels are rising throughout the Quad Cities service area. While major river flooding is not expected in the near term, there is an elevated risk for ice jams to develop and move as temperatures remain above freezing. Ice jams have formed along the Rock River. There are expected to be fluctuating impacts near the Joslin gage that have reached the minor flood level. Impacts at the action criteria have been observed at the Moline gage. Ice jam flooding has led to the closing of Prophetstown State Park. A separate ice jam was spotted at Lyndon, IL. Currently, river flood watches and warnings have been issues along the Rock River from the Como gage to the confluence with the Mississippi River for ice jam impacts and concerns. River stretches of higher concern: - Lower Rock River from Como, IL to confluence with the Mississippi - Lower Wapsi from Anamosa to DeWitt - IA Maquoketa River near Maquoketa, IA - Pope Creek and Edwards River in Mercer County - Henderson Creek in Henderson County && .CLIMATE... Issued at 240 AM CST Wed Jan 31 2024 Record High Temperatures for February 1st... Burlington.....61 in 1911 Cedar Rapids...54 in 1911 Dubuque........51 in 1877 Moline.........58 in 1911 && .DVN WATCHES/WARNINGS/ADVISORIES... IA...Dense Fog Advisory from midnight tonight to 11 AM CST Thursday for IAZ040>042. IL...Flood Watch through Thursday morning for ILZ009-015. MO...None. && $$ UPDATE...Ervin SHORT TERM...08 LONG TERM...08 AVIATION...Ervin HYDROLOGY...Wilson CLIMATE...08
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
535 PM CST Wed Jan 31 2024 ...New AVIATION... .SHORT TERM... (Tonight through Thursday night) Issued at 213 PM CST Wed Jan 31 2024 A pleasant last day of January is continuing across South-Central Texas this afternoon. Winds are light from a generally south/southeast direction with some passing high clouds overhead. This is leading to temperatures in the 60s to near 70 degrees this afternoon. Highs later today will be in the upper 60s to lower 70s. For tonight, persistence will win out with continued high level cloud cover and light winds in place. Lows tonight will be a few degrees warmer than last night as high level clouds help keep temperatures slightly warmer across the region. Will have to watch for some potential for fog in the south. HRRR soundings show some potential, but deterministic/mos guidance does not show much. HREF probabilities are showing about a 30 percent chance for half mile visibility and with that will put in a mention of patchy fog. For tomorrow, we should see high temperatures right at or just below today`s values as some possible mid-cloud cover could help keep things slightly cooler. Wind speeds tomorrow night will be highest in the north, but in the central and southern counties, should be light enough to introduce the possibility of some patchy fog. Dewpoints should creep into the middle 50s, which should help aide in the development of some patchy fog. Lows tomorrow night will warm accordingly, and only reach into the lower to middle 50s. Otherwise, no major concerns are anticipated during the short-term portion of the forecast. && .LONG TERM... (Friday through Wednesday) Issued at 213 PM CST Wed Jan 31 2024 Southerly flow in the low-levels remains in place across all of south central Texas on Friday. Some patchy morning fog may develop from the coastal plains northward into the western Hill Country, I-35 corridor, then westward toward the Rio Grande plains. The SREF and several other hi-res members show fog development may extend farther north through the remainder of the Hill Country and southern Edwards Plateau. We will continue to monitor and expand the mention of fog as needed in subsequent forecasts. An active weather pattern is expected to develop beginning mid to late evening Friday across portions of the wester Hill Country and southern Edwards Plateau. A cold front approaching from the west along with a negative-tilt upper trough and strong jet will aid in the development of scattered showers and thunderstorms. A broken line of convection will likely form around Midnight just west of the I-35 corridor, then move eastward through the early morning hours. Some strong to severe thunderstorms remain possible across most of the region and a Marginal Risk (level 1 of 5) for severe weather is in place Friday evening into early Saturday morning. Damaging winds and large hail remain the main severe weather concerns. We will also need to monitor for surface low development ahead of the front as this may provide some locally backed winds in the low-levels. As of now, it looks like any organized surface low development would be favored near the coast. WPC also maintains a Marginal Risk (level 1 of 4) for locally heavy rainfall for the Hill Country eastward through the I-35 corridor and coastal plains. Average rainfall amounts of 0.5-0.75" are expected for the Hill Country, with amounts increasing into the 1.0-1.5" range from I-35 eastward. There will be some locally higher rainfall amounts and with the recent rains, some minor flooding may develop in areas that see the higher totals. Rain chances may linger a little longer than previously advertised into Saturday morning as the latest round of guidance has slowed the eastward progress of the upper trough axis. For the afternoon, rain chances decrease and shift to areas east of I-35. Out west across the Rio Grande, southern Edwards Plateau and Hill Country, breezy to windy conditions will develop behind the Pacific front Saturday afternoon. Fire weather concerns may develop near the Rio Grande on Saturday, especially in areas where little to no rain is observed. Dry weather is in store for all areas Sunday as gusty northwest winds develop behind the Pacific front. This will most likely result in a Wind Advisory across most of the region, with the stronger winds over the Hill Country westward to the Rio Grande. Fire weather concerns will also increase on Sunday as dry air and mild temperatures drop afternoon humidity levels into the teens to near 25% over the Rio Grande plains, southern Edwards Plateau and Hill Country. Breezy conditions continue into Monday with winds finally easing Monday night. Surface high pressure in place on Tuesday will bring a return of southerly winds to the Rio Grande, with northerly winds east of I-35. Return southerly flow develops across all areas on Wednesday as another upper level system begins to develop over the western U.S. && .AVIATION... (00Z TAFS) Issued at 535 PM CST Wed Jan 31 2024 VFR conditions are expected through the period. Mid and upper level cloud cover will continue to stream overhead through Thursday morning before we begin to see an increase in lower level cloud cover. Any ILS cigs should hold off through the end of this TAF period, however. There is a low chance (15-20%) for some patchy fog at KSAT/KSSF during the early morning hours Thursday, which is too low to mention in the TAFs, but we will continue to monitor in case confidence increases. Mainly light and variable winds are expected overnight, with winds increasing to around 10kts out of the S/SE during the day Thursday. && .PRELIMINARY POINT TEMPS/POPS... Austin Camp Mabry 73 49 69 55 / 0 0 0 0 Austin Bergstrom Intl Airport 72 47 70 55 / 0 0 0 0 New Braunfels Muni Airport 72 47 71 55 / 0 0 0 0 Burnet Muni Airport 71 47 70 54 / 0 0 0 0 Del Rio Intl Airport 73 51 75 55 / 0 10 0 0 Georgetown Muni Airport 72 47 69 55 / 0 0 0 0 Hondo Muni Airport 72 47 71 53 / 0 0 0 0 San Marcos Muni Airport 72 47 70 55 / 0 0 0 0 La Grange - Fayette Regional 72 48 69 55 / 0 0 0 0 San Antonio Intl Airport 71 49 69 55 / 0 0 0 0 Stinson Muni Airport 73 49 71 56 / 0 0 0 0 && .EWX WATCHES/WARNINGS/ADVISORIES... None. && $$ Short-Term...29 Long-Term...Platt Aviation...Gale
Area Forecast Discussion
National Weather Service Grand Junction CO
548 PM MST Wed Jan 31 2024 .KEY MESSAGES... - A strong winter storm system looks to bring widespread mountain snow and valley rain or a mix with potential for over a foot of snow in some mountain areas Thursday night into the weekend. - The heaviest snow will focus in the southern mountains Thursday night and Friday then into the central and northern mountains Friday night and Saturday. - Overall the precipitation begins to shut down on Sunday. Travel in the higher elevations will likely be difficult at times within this active period. - Another storm system looks to bring more rain and snow to the region mid next week. && .SHORT TERM /THROUGH THURSDAY/... Issued at 349 PM MST Wed Jan 31 2024 Satellite imagery shows the deep low off the coast of British Columbia and the Pacific Northwest with the trough extending south over the Eastern Pacific pushing the atmospheric river (AR) to the northeast into California and the Sierra Nevada Range. The Axis of the ridge appears to be moving out onto the Front Range. Orographic cumulus is forming along the San Juans due to the increases southwest flow indicating the low-level moisture in place that moved up from the south with the weak low that has been trapped under the ridge the last few days. This low is over eastern Utah and is now starting to drift east into Western Colorado. The low pushed the upper level moisture that moved up it farther east over the San Luis Valley, keeping Western Colorado mostly clear today. With all the sunshine, we will likely see a few more record high temperatures again today. Though there isn`t any upper level dynamics to support convection over the southwest San Juans, cannot rule out sprinkles or flurries this afternoon due to the strong orographic forcing. The models are tracking features fairly well, but there is already significant variation on the placement of the shortwaves circulating in the low pressure system. This is causing the models to diverge early in the runs on the depth of the trough and the timing of the shortwave as it digs into the base. The GFS is running a little ahead with the Euro close behind and the Canadian and NAM trailing. The models that delay the descent of the shortwave into the trough until it starts getting a negative tilt are tending to eject the low farther south over New Mexico, less active solution for the region, while the the GFS drops the shortwave into the base of the trough earlier that kicks it more easterly into southern Colorado, a wetter, more active solution. As a result, there is quite a bit of variation among the solutions for eastern Utah and Western Colorado for this upcoming storm. For this reason, continued the Winter Storm Watch for the Abajo, La Sal and San Juan Mountains, and the Uncompahgre Plateau to look at the next run of the models before upgrading to warnings or advisories. Expect clouds to move up from the Desert Southwest early tomorrow ahead of the trough. Looks like the high mountain valleys of the San Juans and the Gunnison Valley will see radiative cooling before the clouds move in, but tempered the low in Silverton a bit. The Gunnison Valley will likely see another round of fog and low stratus in the morning. Additionally, the clouds will limit diurnal heating tomorrow, so look for cooler high temperatures. Expect isolated light rain showers across eastern Utah and southwestern Colorado below about 8500 feet with scattered snow showers over the mountains. Showers will increase tomorrow evening and overnight into Friday morning over the higher terrain of eastern Utah and southwestern Colorado with snow levels dropping to 7000 feet as the deeper moisture from the AR arrives in the region and jet divergence moves in overhead. By Friday morning, valley rain and mountain snow will start spreading into the central Colorado mountains. Of interest to watch: the HRRR is pushing more of the moisture and convection north into northeastern Utah and northwestern Colorado which could significantly increase the QPF through the Uinta and lower Yampa River Basins. && .LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/... Issued at 349 PM MST Wed Jan 31 2024 The trough becomes negatively tilted by Friday as strong southerly flow continues to bring impressive lift to the southern mountains, with this surge of moisture expanding northward towards the southwest facing slopes of the central mountains as well by Friday. Significant moisture, thanks to a strong atmospheric river will be drawn into the Desert Southwest and through the Four Corners, giving plenty of fuel for abundant precipitation. Early on in this storm`s life cycle, temperatures will be quite mild, so snow levels will be higher between 7000 to 8000 feet by Friday afternoon. This draws complexities with forecasting precipitation type in the lower elevations and the mid slopes as most lower elevations look to stay rain, with lots of it. Another added element is the instability as CAPE values will be fairly widespread with 100 to 200 J/kg, sufficient enough in early February to see thunderstorms and potential for snow squalls and banded precipitation. The colder air doesn`t move in until Friday evening into Saturday and even then, H7 temps are only expected to get down to -6C to -9C roughly...which is enough to lower snow levels gradually to around 5000 to 6000 feet or so by Saturday. The flow also shifts around to west to northwest, so the focus for heavier snowfall shifts from the southern mountains towards the northern and central mountains, hence the current end time of the Winter Storm Watch for the southern mountains at 12Z (5 am MDT) Saturday morning. Much colder air surges in by Saturday evening as H7 temps drop to -10C to -12C with favored orographic lift on the north and west facing slopes. When looking at QG forcing, the bullseye tends to be favoring the south Friday and expands or elongates to the northwest across the northern and central areas by Saturday. It is interesting to note that by Saturday morning into the afternoon, lee side cyclogenesis takes place in southeast Colorado as the H8, H7 and H5 lows become closed off and vertically stacked. This means an intensifying period of the cyclone where snow rates are likely to pick up for the central and northern mountains with wraparound moisture as well. You can also throw in the northwest San Juans that look to be favored in this pattern based on the proximity of the low. Confidence is increasing for potential for significant snowfall accumulations in the mountains from south to north, so decided to expand the Winter Storm Watch to also include the remaining northern and central Colorado mountains as well as the northwest San Juans where potential for 1 to 2 feet of snow is looking more probable. Travel will be impacted from Thursday evening through Sunday morning so make sure to be prepared and check the latest forecast as more details come to light and potential for upgrades from the Watch. Most rates look to lessen by Saturday evening, however given the slow moving nature of these lows sometimes and continued favored orographics with the colder air, snow could linger a bit longer than current projections indicate. Therefore, the Winter Storm Watch for the northwest San Juans, northern and central Colorado mountains will start at 18Z (11 am MST) Friday and continue through 12Z (5 am MST) Sunday morning. A ridge of high pressure will move in by Sunday evening as this system moves out by another potential AR event is on the doorstep as more moisture slams into California from the Pacific as another low pressure trough approaches the west coast. As a result, southwest flow will increase early next week with this system bringing the next round of precipitation to the area by Tuesday and beyond. February is looking to start off active and continue to be active through at least mid February as far as we can tell. && .AVIATION /00Z TAFS THROUGH 00Z FRIDAY/... Issued at 548 PM MST Wed Jan 31 2024 Clouds will be on the increase through the period as the next storm system digs into the western states. This will lead to continued VFR conditions with CIGS remaining above ILS break- points through early Thursday morning. High-based moisture will bring isolated showers to eastern Utah and southwest Colorado in the afternoon with activity increasing Thursday evening. Winds will remain light and terrain-driven. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...Winter Storm Watch from Friday morning through late Saturday night for COZ004-009-010-012-013. Winter Storm Watch from Thursday afternoon through late Friday night for COZ017-019. Winter Storm Watch from Friday morning through Saturday afternoon for COZ018. UT...Winter Storm Watch from Thursday afternoon through late Friday night for UTZ028. && $$ SHORT TERM...DB LONG TERM...MDA AVIATION...TGJT
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
550 PM CST Wed Jan 31 2024 .KEY MESSAGES... - Uncertain cloud cover trends will affect temperatures at least into the start of the weekend, as well as any fog potential - Well above normal temperatures and otherwise exceptionally benign weather for this time of year through the period && .DISCUSSION... Issued at 206 PM CST Wed Jan 31 2024 Through Friday Night Despite the increasing sun angle and day lengths as we enter February, we`re still firmly in the "fun with stratus forecasting" time of year. The back edge of stratus that resulted in under-performing high temperatures has progressed to west of the I-39 corridor this afternoon. There`s also been a scouring of low clouds gradually pushing down the western shore of Lake Michigan, though it doesn`t appear this will have made it into far northeast Illinois before sunset. Stout southwesterly low-level winds above the inversion tonight associated with the strengthening nocturnal low level jet is expected to continue to steadily push the back edge of the lingering stratus east-northeastward, with uncertainty on exact timing. Even as clouds diminish, robust flow off the deck translating to occasional breeziness at the surface, especially over Chicago, should limit the temperature drop. Didn`t have enough confidence for any explicit fog mention, though there may be some potential over southeast and far northern sections, to be assessed for subsequent updates. On Thursday, expecting a large area of stratus to be located to our east, northeast, and north as a backdoor cold front pushes southward. Low-level flow turning northerly and then northeasterly should cause the stratus to "slosh" back south and southwest with time, and should keep the warmest high temps (upper 40s-lower 50s) confined to south of I-80, and low-mid 40s for the rest of the area. With the guidance with the exception of the RAP and HRRR generally doing a poor job of handling the stratus today, that should continue into Thursday night through Friday night and lowers confidence in the sky cover and temperature forecast. With east-northeast low-level flow coming from area of existing low clouds and uncertainty if a lowering inversion can mix out the clouds, trended sky cover more pessimistic on Friday-Friday night to the partly-mostly cloudy range, lowest % wise in our far south. Temps could approach the upper 40s Friday afternoon if enough sun does materialize. Saturday through Tuesday The sky cover uncertainty extends into Saturday as we go into a blocky regime aloft with well above normal thermal profiles. We`re showing decreasing clouds on Saturday, but that`s more of a wait and see on how things go through Friday before confidence can increase in sunnier conditions. Nonetheless, temperatures will still be solidly above normal, just how far above being the question mark. With an upper level low ejecting out of the southwest being pressed south by blocking over central NOAM, we`ll have an exceptionally long period of benign weather with surface high pressure predominating through mid next week. Winds will be generally from the northeast, resulting in rare winter time "cooler near the lake" conditions lakeside amidst otherwise well above normal temperatures in the 40s (with upside potential pending sky cover trends). Next chance of precipitation will come beyond day 7. The tendency during this stretch will be to wonder if "winter is over", though consistent long range ensemble guidance has been pointing toward the return of a more wintry pattern (western ridging and eastern troughing with high latitude blocking establishing), at least temperature wise, toward Valentine`s Day. Castro && .AVIATION /00Z TAFS THROUGH 06Z THURSDAY/... Issued at 550 PM CST Wed Jan 31 2024 Forecast concerns include... Low mvfr cigs this evening and again Thursday. Wind shift to northeast Thursday afternoon. The current area of low clouds continues to erode from the southwest, as well as from the northeast and the expectation is for the clouds to scatter out across the Chicago terminals this evening. Assuming that happens, the low mvfr clouds are expected to return Thursday afternoon, though only medium confidence for timing. Once the low clouds return, they are expected to continue into Thursday evening. Southwest winds will continue through mid/late Thursday morning then turn westerly and northwesterly fairly quickly though early afternoon. Winds are then expected to shift northeast during the mid afternoon with speeds increasing into the 10-15kt range, especially into Thursday evening. High confidence for the wind shift to northeast, but timing tweaks may still be needed with later forecasts. cms && .LOT WATCHES/WARNINGS/ADVISORIES... IL...None. IN...None. LM...None. && $$ Visit us at weather.gov/chicago
Area Forecast Discussion...UPDATED
National Weather Service Memphis TN
608 PM CST Wed Jan 31 2024 ...New AVIATION... .SYNOPSIS... Issued at 250 PM CST Wed Jan 31 2024 Calm and dry conditions will remain across the Mid-South through the end of the work week. Temperatures will be near to slightly above normal with highs in the 50s and 60s and lows in the 30s and 40s areawide. An upper level disturbance will bring showers back into the forecast Saturday afternoon through Monday morning. Dry and calm conditions will move back across our CWA Tuesday. && .DISCUSSION... (This evening through next Tuesday) Issued at 250 PM CST Wed Jan 31 2024 A surface high pressure currently centered over the lower Mississippi Valley and northwest flow aloft will keep skies clear and light winds through the remainder of today. Upper level ridging will quickly build across the Mid-South beginning late this evening. Clear skies, calm winds, and ample radiational cooling will create a great environment for fog development overnight tonight and into the early morning hours. Patchy fog formation and reduced visibilities is likely areawide with some local areas of dense fog possible. The aforementioned upper level ridging will keep benign weather across our CWA through the end of the work week. Upper level ridging will begin pushing east as quasi-zonal flow aloft moves over the area Thursday night. A makeshift Rex Block will set up over the CONUS Friday evening. The associated upper level trough and upper level low pressure system will set up over the four corners region and track showers west to east across the Mid-South Saturday afternoon through Monday afternoon. Current forecast QPF values are around .25- 1.5 inches areawide, greatest amounts over Northeast Central Arkansas and Northwest Mississippi. Forecast dewpoints and sounding do not currently support thunderstorm development with this system. The aforementioned low will retrograde southeast as a surface high pressure and northwest flow builds back over the region Tuesday bringing dry conditions back over the Mid-South Tuesday. As far as temperatures are concerned, we will stay around normal to slightly above normal with highs in the 50s and 60s and lows in the 30s and 40s for the foreseeable future. The latest CPC 8-14 day outlook has our temperatures staying above normal, resulting in a pretty pleasant start to our February. AEH && .AVIATION... (00Z TAFS) Issued at 608 PM CST Wed Jan 31 2024 VFR and light winds to prevail at MEM during the overnight hours. 00z surface analysis shows a 1023mb pressure ridge axis along the MS River. This feature will move to west central AL by 12z, with light southerly winds and clear skies in the interim. HRRR and HREF mean RH fields depict higher fog probabilities over the delta prior to sunrise. Fog potential at TUP may be underdone in guidance, given the weak wind fields. Urban heat island effect and active overnight traffic pattern should should keep MEM VFR. PWB && .MEG WATCHES/WARNINGS/ADVISORIES... AR...None. MO...None. MS...Flash Flood Watch through Thursday morning for MSZ007-011-020. TN...None. && $$ PUBLIC FORECAST...AEH AVIATION...PWB
Area Forecast Discussion
National Weather Service Marquette MI
554 PM EST Wed Jan 31 2024 .KEY MESSAGES... - Unseasonable warmth to round at the afternoon for much of the fcst area. - Cold front arriving late tonight and early Thu may lead to very light drizzle and very light freezing drizzle in the high terrain of northwest to north central Upper MI near daybreak. - Light wintry precipitation is possible across portions of the north-central and western UP early Thursday. - Unseasonably warm weather and little, if any precipitation, through at least the middle of next week. && .SHORT TERM /THROUGH TONIGHT/... Issued at 302 PM EST Wed Jan 31 2024 Low clouds have cleared out of most of the fcst area today, allowing for an unseasonably warm aftn as 850mb thermal ridge upwards of 9C per latest RAP analysis noses into western Upper MI. Over the Keweenaw, low clouds linger under westerly winds as moisture has not been able to mix out of the marine layer. Those w winds have been gusting to around 45mph this aftn. Low clouds also linger in the sw flow off Lake MI into the eastern fcst area. Low clouds returned to Gogebic County, but those are mixing out. Now that we`re moving into Feb, the gradually increasing midday sun angle each day is allowing for solar insolation on the lower albedo forested landscape of the U.P. to begin having a little more noticeable affect on warming. Where low clouds have cleared, temps have soared thru the 40s F today. KIMT and the city of Marquette have been the warm spots at 50F. Here at NWS Marquette, the high so far has been 47F, breaking the old record of 42F set in 1993. For the city of Marquette, the unofficial 50F readings noted at a couple of obs site are higher than the record of 48F set in 2016. City of Marquette records date back to 1857, so that would be notable if the official obs site does end up exceeding 48F this aftn. If the official obs site at Iron Mountain ends up with a high above 45F, which it should have, that will also be a record. Records at Iron Mountain date back to 1899. Where low clouds continue to hang on or where winds are off of the Lakes, temps are in the mid to upper 30s F. For tonight, shortwave trof swinging across northern Ontario and Upper MI/Lake Superior will send a cold front s across Lake Superior, arriving in northern Upper MI around 12z Thu. Another surge of low clouds is noted following the cold front that is currently well n in northern Ontario. So until the front arrives, most of the area will see clear to partly cloudy skies. Toward 12z, low clouds will arrive across nw into n central Upper MI. There is a slight chc 15-20pct, that upsloping of low-level moisture could lead to some patchy -dz/-fzdz in the high terrain, but better chc for that will occur after 12z. Expect low temps around 32F in general, but some interior spots that fully decouple could easily slip down into the mid 20s F tonight. && .LONG TERM /THURSDAY THROUGH TUESDAY/... Issued at 236 PM EST Wed Jan 31 2024 A sprawling positive height anomaly across central Canada will result in a mostly quiet and warm spell across the Upper Great Lakes. This should begin by Thursday afternoon/evening. Before then though, the modestly cold airmass building in behind an early morning cold front will support a cooler and upslope flow regime with a somewhat shallow saturated profile. This could yield a mix of light drizzle, freezing drizzle, and/or snow, mainly near Lake Superior. Impacts associated with this are not expected. High pressure will build through northern Ontario Thursday, then drop south into the Upper Great Lakes Friday and Saturday. While surface ridging may fluctuate some late weekend and next week, stout mid-upper level ridge parked overhead will support quotidian dry and unseasonably mild conditions through at least mid-week. The only chance precip looks possible is Tuesday/Tuesday night, but antecedent dry air overhead looks to limit any precip edging into our area. Temperatures will continue to run above normal in this period, warming into the mid 30s to low 40s most days and then sinking into the 20s or even high teens overnight. && .AVIATION /18Z TAFS THROUGH 18Z FRIDAY/... Issued at 554 PM EST Wed Jan 31 2024 VFR conditions will continue overnight at all sites. MVFR clouds behind a cold front with north to northeast winds will lead to some upslope flow and clouds. This will start first at CMX late tonight and at IWD and SAW Thu morning. SAW will see some IFR conditions Thu afternoon. There is a small potential that sharper upsloping nne winds at SAW could yield some -dz/-fzdz Thu morning, but potential is too low to include mention in fcst attm. && .MARINE... Issued at 236 PM EST Wed Jan 31 2024 Stronger southwest winds upwards of 25-30 knots will lighten this evening, then shift northwesterly overnight as a cold front shifts south through the region. Colder air behind the front will support winds increasing to 25-30 knots by morning. Winds lighten through the day and settle back below 20 knots by evening. Stout and persistent high pressure will then settle in behind the front and maintain a light wind regime across Lake Superior through at least the middle of next week. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... Small Craft Advisory until 6 PM EST /5 PM CST/ this evening for LSZ241. Small Craft Advisory from 1 PM EST /noon CST/ Thursday to 1 AM EST /midnight CST/ Friday for LSZ240-241. Small Craft Advisory until 1 AM EST Thursday for LSZ242>244. Small Craft Advisory from 7 AM Thursday to 1 AM EST Friday for LSZ242>245-251. Small Craft Advisory from 7 AM Thursday to 7 AM EST Friday for LSZ248>250. Lake Michigan... Small Craft Advisory until 10 PM EST this evening for LMZ248. Small Craft Advisory until 6 PM EST this evening for LMZ250. && $$ SHORT TERM...Rolfson LONG TERM...JTP AVIATION...07 MARINE...JTP
Area Forecast Discussion
National Weather Service Phoenix AZ
516 PM MST Wed Jan 31 2024 .UPDATE...Updated 00z Aviation Discussion... && .SYNOPSIS... The unseasonably warm temperatures will last for one more day before a cold front and rain moves through the area Thursday into early Friday. Below normal high temperatures are then expected for Friday through the weekend with lingering shower activity over the Arizona high terrain lasting into Saturday. After a brief period of drier conditions later this weekend into Monday, yet another weather system is expected to bring widespread rainfall to the region during the middle of next week. && .DISCUSSION... Temperatures across the Desert Southwest continue to run as much as 10 degrees above normal, though the record high temperature of 86 degrees in Phoenix remains well out of reach. Meanwhile, dewpoints are running several degrees higher than at this time yesterday and this portends a continued moistening trend and an increased threat of precipitation. Latest water vapor imagery reveals a large cyclonic circulation and several, smaller embedded vortices across the eastern Pacific. Further east, a well-defined and elongated atmospheric river is also evident ahead of this system extending from northern California south and westward into the subtropics. Latest model guidance indicates IVTs will likely diminish as the AR comes ashore and migrates eastward into Arizona, nevertheless a widespread rain event is still anticipated Thursday and Thursday night. General model consensus has trended a bit quicker and rainfall is first expected to develop Thursday morning across southeastern California. Latest HREF depicts this activity weakening somewhat across southwestern Arizona before deeper moisture and strong jet and vorticity-forced ascent promote an expansion and strengthening of the rainfall across south-central Arizona Thursday night. Although instability will generally be weak, upper quartile CAMs do indicate SBCAPEs of 100+ J/kg, which may result in localized convective elements and enhanced rainfall rates, particularly along the eastward propagating cold front. WPC has consequently expanded the marginal risk of excessive rainfall further eastward to include southwest and south-central Arizona. Latest runs of the HRRR depict a sharp back edge to the precipitation shield across the Phoenix area early Friday morning, though isolated showers will persist across the higher terrain north and east of Phoenix with the moist upslope flow. The upper trough and associated cold pool aloft will also promote additional weak instability and the redevelopment of showers and isolated thunderstorms Friday afternoon, though again this will mainly be concentrated north and east of Phoenix. At the surface, conditions will also be considerably cooler than they have been with high temperatures generally in the lower 60s. Expected storm total rainfall ranges from two tenths to one third of an inch across southwestern Arizona and southeastern California. Across south-central Arizona, a half of an inch to three quarters of an inch is expected in the Phoenix area, while upwards of an inch is expected in the higher terrain north and east of Phoenix though the latest NBM also indicates the largest amount of uncertainty in these areas. Snow levels also remain too high for any measurable snow, except across eastern Gila County above 6000 feet in elevation. && .PREVIOUS DISCUSSION... The unsettled weather pattern will not stop with this late week system as deep large scale troughing will persist off the West Coast through the weekend into next week. The flow aloft over our region will eventually transition to a zonal pattern over the weekend keeping below normal temperatures with highs in the low to mid 60s in place from Friday through the weekend. By Sunday into Monday, the next weather system will begin to deepen off the California coast prompting a ridge to briefly build over the Desert Southwest. This will in turn lead to some warming for Monday with highs back to near normal, but it will also lead to increasing moisture and clouds into our region. Model ensemble guidance continues to show the deepening Pacific trough to our west over the weekend tapping into good quality sub- tropical moisture and streaming it into our region early next week. This initial wave of moisture advection along with a slow moving jet streak setting up from well west of central Baja into the Desert Southwest may bring some shower activity as early as Monday night into early Tuesday. However, guidance is starting to finally consolidate the likely rainfall time frame for the first part of this large slow moving weather system and for now shows late Tuesday into Wednesday likely being the best potential for warm air advection type rainfall over much of our region. This trough will be a slow mover and will likely present several opportunities for rainfall through the end of next week as the main low center may not move through the Desert Southwest until sometime around next Friday or Saturday. Moisture levels for much of next week are likely to be plenty sufficient for ample rainfall over the region during this likely several day event as GEFS PWATs are shown to be around 0.60-0.70" (150-175% of normal), while the EPS is slightly higher. Considerable uncertainty remains as far as the timing and how much precipitation will be possible during a Tuesday-Friday time frame, but preliminary QPF shows 1-2" may be possible over some of the lower deserts. Considering this additional rainfall will be falling on already somewhat saturated soils, there will be at least some flooding concerns in area washes. && .AVIATION...Updated at 0010Z. South-Central Arizona including KPHX, KIWA, KSDL, and KDVT: The main aviation concerns, primarily towards the end of the TAF period Thursday evening, will be the deteriorating CIGS and the increased rainfall coverage. In the meantime, through early Thursday morning, tranquil conditions will prevail with light winds aob 6 kts prevailing. Wind direction through early this evening will be primarily southerly (170-200 deg) but will likely feature a lot of variability with the potential for periodic shifts out of the west to southwest before shifting back to the east to southeast by the 03Z-05Z timeframe. Heading into the mid to late morning hours on Thursday, winds are expected to veer into a more southerly direction with sustained speeds increasing 10-15 kts and gusts at times reaching 20-25 kts. Winds during the early to mid-afternoon hours will veer to southwest to south- southwest. Ceilings through Thursday afternoon will remain above 10 kft. By Thursday evening, a batch of widespread light to moderate rainfall will be moving in from the west and be affecting the metro after 03z, with rapidly deteriorating CIGS/VIS into the MVFR category. Southeast California/Southwest Arizona including KIPL and KBLH: The main aviation weather concerns heading into Thursday will be the deteriorating CIGS and the increased rainfall coverage. In the meantime, tranquil weather conditions with light winds aob 6 kts will prevail into early Thursday morning with southerly winds at KBLH and east to southeast winds at KIPL, becoming more variable overnight tonight. The overall wind pattern throughout the day on Thursday will continue to feature east to southeast winds at KIPL and southerly winds at KBLH with speeds generally aob 10 kts, although KBLH at times may briefly see some higher gusts into the teens. Otherwise, VCSH will be entering the picture after 16z with a period of steady light to moderate rainfall activity after 19z. As the steadier rainfall activity moves in, CIGS will be dropping down to as low 4-5 kft with a 40-50% chance of dropping even further into the MVFR category towards the end of the TAF period. && .FIRE WEATHER... The dry and unseasonably warm weather will continue today, but then give way to a cold front and rain passing through the area later on Thursday into early Friday. Moisture will also be increasing over the next couple days with minimum afternoon humidity levels around 30% today and as high as 60% over the western districts Thursday. Winds will remain relatively light today with more of a southerly direction starting later in the day, however winds will become breezy over much of the area on Thursday. Wind gusts late Thursday afternoon and evening may reach between 30-35 mph across portions of south-central Arizona. Cool conditions along with elevated humidities will then be seen Friday into the weekend with lingering showers mainly over the Arizona higher terrain. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ DISCUSSION...Hirsch PREVIOUS DISCUSSION...Kuhlman AVIATION...Lojero FIRE WEATHER...Kuhlman