Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/18/20

Area Forecast Discussion
National Weather Service La Crosse WI
831 PM CST Mon Feb 17 2020 .UPDATE... Issued at 825 PM CST Mon Feb 17 2020 Extended the advisory west of the Mississippi River out to midnight as the snow is exiting the area slower than previously expected. With a couple more hours of moderate snow, with visibilities down to a mile or less, roads will remain snow covered and slippery. Additional accumulations for the rest of the evening should be in the 1 to 2 inch range for most locations. If trends in the HRRR are correct, the snow should begin to taper off in the western sections between 10 pm and midnight and in the east after midnight. For now, didn`t extend the eastern sections as the HRRR has been showing the a diminishing trend after midnight as well. && .SHORT TERM...(Tonight) Issued at 150 PM CST Mon Feb 17 2020 A challenging forecast persists heading through this evening. Some amplification of an approaching mid-level shortwave trough is expected as in interacts with another shortwave approaching from the northern plains. The trend has been for a slowing of the onset of accumulating precip in the high res models, especially to the north and east. Model guidance has struggled with the initial snow across northeast IA/southwest WI with reports so far of a few inches already. Accordingly, have added Grant County into the Winter Weather Advisory. Still may see a transition to a mix/rain for far southern areas as warmer air tries to lift north. In addition, a several hour window of potentially moderate/heavy snow is still expected this afternoon/early evening as the additional snow develops from the west. In this swath, 2-5+ inches of snow with rates exceeding 1 in/hr are possible, currently favoring near or just south of the MN/IA border area into central WI. The 17.12Z HREF suggests a period of at least 1 in/hr rates across far northeast IA from around 3-7 pm, spreading into southwest/central WI in the 6-10 pm window. Given the marginal thermal profiles, rain could mix in at times under lighter rates or where temps are a bit warmer, such as river valleys. By late evening, precip should wind down as the weak surface low pulls into the northern Great Lakes. .LONG TERM...(Tuesday through Monday) Issued at 150 PM CST Mon Feb 17 2020 Beyond the early week system, a quiet week weather-wise is ahead, with temps the primary challenge. Tuesday will be noticeably cooler and breezy with highs in the teens/20s. The strongest surge of low level cold advection will arrive Tuesday afternoon as a secondary upper trough skirts the northern Great Lakes. Some clearing is expected through the day as a strong surface high begins to build in from the Canadian prairies, although could see a period of stratus and perhaps some flurries Tuesday afternoon/evening before drying/clearing take place from the northwest. Temps will fall below zero over much of the area Tuesday night, with the core of the cold airmass situated across the area on Wednesday as 850 mb temps descend into the -15 to -18C range. Highs will be mainly in the single digits/teens. With the ridge axis sitting just to the west, Wednesday night will be the coldest night of this short-lived cold spell, with lows well below zero for most areas. The surface high center will cross the area on Thursday. Limited mixing and a cold start will keep highs in the teens to near 20, despite slowly moderating low-level thermal fields. Much milder Pacific air will spread into the Midwest late this week into early next week as the upper air pattern flattens and the the surface ridge slides east. Highs by the weekend will be back into the 30s to perhaps 40s for some. General indications are that an upper trough will eject from the southern plains Sunday with a longwave trough deepening over the Rockies by early next week, but confidence in the details of this evolution and precip chances from late weekend and beyond is low right now. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 509 PM CST Mon Feb 17 2020 Surface analysis late this afternoon shows an area of low pressure over northwest Missouri with a inverted trough of low pressure extending north into northwest Wisconsin. Snow was occurring in the vicinity of the inverted trough with IFR visibilities. Expect that this snow will continue for a good share of the evening at both airports until the short wave trough over South Dakota swings across the region. Once the snow ends, the visibility should rapidly increase but with ceilings remaining IFR/MVFR overnight. VFR conditions should develop Tuesday morning as an area of high pressure builds in from the northwest allowing the clouds to scatter out. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...Winter Weather Advisory until midnight CST tonight for WIZ029- 032>034-041>044-053>055-061. MN...Winter Weather Advisory until midnight CST tonight for MNZ079- 086>088-094>096. IA...Winter Weather Advisory until midnight CST tonight for IAZ008>011-018-019-029-030. && $$ UPDATE...04 SHORT TERM...JM LONG TERM...JM AVIATION...04
Area Forecast Discussion
National Weather Service Columbia SC
727 PM EST Mon Feb 17 2020 .SYNOPSIS... A series of upper disturbances and a frontal boundary will bring rain to our forecast area Tuesday through Thursday. Drier and cooler air will settle into our region Friday and Saturday. Moderating temperatures expected Sunday and Monday with rain moving back into the picture by Monday. && .NEAR TERM /THROUGH TUESDAY/... The upper level flow begin to turn back towards the southwest in response to upstream troughing over the southern Rockies. This will begin pushing moisture, along with a surface warm front, back towards the north through the night. Much of the night still should remain dry, with rain chances increasing towards Tuesday morning from west to east. Clouds will be on the increase this evening, and are expected to lower as the warm front nears from the south. Expect patchy to potentially more widespread fog to develop late tonight although latest HRRR suggest bulk of fog back in central /north GA into the Upstate. The cloud cover should limit radiational cooling, keeping lows in the upper 40s northern Midlands to lower 50s in the CSRA. && .SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/... Tuesday and Tuesday night...Warm front will be north of the forecast area Tuesday morning with with the first of a series of impulses bringing rain to the area by mid morning. Model sounding indicate a relatively stable air mass through the day however with southwesterly flow pushing Gulf moisture into the area and corresponding pwat values between 1.4 and 1.5 inches through the day expect rain to continue. Cold front will approach the forecast area Tuesday night and although instability remains weak expect showers to continue as the front begins crossing the area during the early morning hours. Temperatures will range from the low 60s in the northern and western Midlands to the upper 60s in the eastern Midlands and southern CSRA. Lows will be in the low 50s along the NC Border with upper 50s in the southern Midlands and CSRA. Wednesday and Wednesday night...Cold front will drift just south of the forecast area through the day Wednesday and be just south of the area Wednesday night. Rain chances will remain high through the day Wednesday then begin diminishing through the late afternoon as the front moves south of the area. With the weak forcing expect rain to continue through the day however heavy rain is not expected. Temperatures are a concern as northerly flow could keep temperatures lower depending on timing of the front. Wednesday night the front stalls south of the area and models continue having differences on how far south of the area the front stalls. Expect the front to stall just south of the area which will keep chance pops over the southern half of the area with slight chance for the northern Midlands and Pee Dee. Temperatures will be in the mid 50s to low 60s for highs with low 40s for lows. && .LONG TERM /THURSDAY THROUGH MONDAY/... Frontal boundary will once again return northward on Thursday before pushing offshore Thursday night as low pressure deepens and moves away from the region. This will allow high pressure along with cooler and drier air to build into the region for Friday into Sunday. The next low pressure system will move into the central US on Sunday and with the high pushing offshore southerly flow will again begin pushing moisture into the area. Rain chances will return for Sunday night and Monday as a warm front crosses the region. Temperatures through the long term will be below normal for Thursday through Saturday with near normal for Sunday and Monday. && .AVIATION /00Z TUESDAY THROUGH SATURDAY/... IFR restrictions expected to develop overnight and continue into Tuesday. Moisture will deepen overnight with a warm front lifting into the area. A cold front will approach the area on Tuesday and cross the area Tuesday night. Rain will overspread the terminals Tuesday morning and will continue into Tuesday night. MVFR ceilings are already in place at AGS/DNL/OGB this evening and should also develop at CAE/CUB. Deterioration to IFR/LIFR is expected overnight as moisture deepens and will continue throughout the day Tuesday. As the warm front moves northward overnight, visibilities may also drop to IFR. Light easterly winds will gradually veer to southwesterly by Tuesday evening. EXTENDED AVIATION OUTLOOK...Showers and expected restrictions Tuesday night through Thursday. && .CAE WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. && $$
Area Forecast Discussion
National Weather Service Charleston SC
907 PM EST Mon Feb 17 2020 .SYNOPSIS... High pressure will give way to a warm front lifting north through the area Tuesday before a cold front pushes through on Wednesday. Colder high pressure will then build in from the north through the end of the week as low pressure passes offshore Thursday into Friday. Warmer and eventually wetter conditions are expected early next week. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... As of 9 PM: Based on latest runs of the CAMs, I will lower PoPs to SCHC across the forecast area for tonight. Otherwise, conditions still appear on track for areas to patchy fog to develop late tonight. As of 635 PM: I will update the forecast to increase sky cover through tonight. The mention of fog developing later tonight still looks good. However, based on latest guidance, I will limit QPF to around 0.01 of an inch for tonight. Previous Discussion: Tonight: Within the prevailing west-southwest flow aloft, embedded shortwave energy will spread across the forecast area late tonight. At the surface, inland high pressure will steadily dissipate as a weak low develops offshore under the influence of the shortwave energy aloft. Overall, much of the overnight will be dry. Late tonight, the forecast becomes challenging as a subtle warm front lifts northward and into southeast Georgia. There is considerable model disagreement regarding the development of showers along and near the front. The GFS and ECMWF depict good coverage of rain showers by day break Tuesday. On the other hand, the NAM, HRRR, and RAP are all totally dry and favor areas much further inland. These drier solutions seem to be hitting on where the best low level convergence sets up, which makes sense given the subtle nature of the warm front lifting through the forecast area. Confidence is low and either scenario is plausible, but the forecast has been trended in a drier direction with lower rain chances. By sunrise Tuesday, the forecast now shows 30-40 percent chances well inland, tapering to 20 percent or less along and south of I-16. Fog is also a concern with the presence of good low level moisture, light winds, and the nearby weak front. Model guidance is mixed, but tends to favor southeast Georgia for the best fog chances. The forecast features areas of fog generally along and south of the Savannah River, with just patchy fog further north. Can`t rule out at least patchy dense fog, so we will maintain the mention in the Hazardous Weather Outlook. Lows are forecast to bottom out in the low 50s for most areas. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/... Low to moderate confidence during this unsettled period. Shower chances will increase on Tuesday as a warm front moves north through the area, especially near the CSRA/Midlands/Pee Dee closer to the deeper moisture/upper level energy. A cold front will then move into the area late Tuesday night and push through Wednesday. High pressure will then build in from the north into Thursday as low pressure develops off the northern Florida/Georgia coasts Thursday. The combination of deep moisture and upper level energy will keep conditions unsettled through the period with most places likely to see an inch or more of rain, possibly even 2 to 3 inches in spots, although the risk for significant flash flooding is low. Can`t rule out a few mainly weak thunderstorms Tuesday as some weak instability develops behind the warm front especially south of I-16. Winds will pick up Wednesday night and remain elevated through Thursday as the pressure gradient increases and could see gusts at least near 35 mph especially near the SC coast. A Lake Wind Advisory could also be needed for Lake Moultrie. Temperatures should be above normal through Wednesday night, then well below normal Thursday when temperatures should struggle to rise out of the 40s during the day, especially inland areas. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... Models are in fairly good agreement through the long term period with much cooler weather on tap late week. Any precipitation should end Thursday night as offshore low pressure pulls farther away with relatively quiet weather then returning until warmer weather and rain chances increase Sunday night as the next storm system approaches. Temperatures should be well below normal through at least late week before possibly getting back above normal late in the period. && .AVIATION /02Z TUESDAY THROUGH SATURDAY/... Prior to the 0Z TAFs: Regional observations were generally MVFR with pockets of VFR near the coast. I anticipate that MVFR ceilings will develop over the terminals this evening. Late tonight, A warm front is expected to lift north, arching around sfc high pressure. The combination of llvl lift over the front and high BL moisture should support ceilings to lower to IFR at KCHS, lower at KSAV. In fact, high resolution guidance and SREF probs indicate that conditions will fall to LIFR during the pre-dawn hours. A large patch of showers should pass west to east across the terminals during the daylight hours Tuesday. The rain showers may result in unsettled flight conditions, but should favor IFR to MVFR conditions through most of the day. Extended Aviation Outlook: High confidence in some significant restrictions at KCHS/KSAV through Thursday night with VFR returning Friday. Also, strong northeast winds gusting over 20 knots are expected Wednesday night through Friday. && .MARINE... Tonight: The local waters will be situated between high pressure inland and a weak offshore low for the first part of tonight. This will drive modest northeast flow through this evening, with speeds topping out in the 10-15 knot range. Winds will drop off to less than 10 knots late, but will likely remain out of the northeast ahead of a warm front lifting northward. Seas will average 2-4 feet. Can`t rule out patchy fog in and around the Charleston Harbor late tonight. Overall confidence in fog is low. Tuesday through Saturday: Moderate confidence this period. Generally no significant concerns until late Wednesday after a strong cold front moves through, although some dense sea fog could develop across the nearshore waters Tuesday/Wednesday. High risk for Small Craft Advisories for all waters Wednesday night into Saturday, except probably just through Friday for Charleston Harbor, with Gale Warnings possible Thursday into Friday night especially eastern waters near the Gulf Stream. && .TIDES/COASTAL FLOODING... Increasing northeast winds Thursday into Friday behind a strong cold front could push tide levels high enough to cause minor saltwater inundation, especially along the SC coast. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$ NEAR TERM...NED SHORT TERM...RJB LONG TERM...ETM AVIATION...NED MARINE...BSH/RJB TIDES/COASTAL FLOODING...
Area Forecast Discussion
National Weather Service Des Moines IA
552 PM CST Mon Feb 17 2020 .UPDATE... Issued at 551 PM CST Mon Feb 17 2020 Finally seeing changeover to snow over the northern areas with some heavier snowfall rates expected in the advisory area. Have extended the advisory to 03z due to potential to linger into the evening hours. North of the border in Minnesota, areas along the cold front and weak low already much worse. Though totals here should still be in the 1 to 2 inch or so range, conditions will continue to deteriorate in the next hour to three hours. Also, added an SPS for patchy dense fog over eastern and portions of southeast Iowa where moisture convergence along the warm front extending from the weak low over southern Iowa continues to focus boundary layer saturation. Expecting with the eastward translation of the low that a period of 2 to 3 hours of fog will be the primary length. Currently worse along the I80 corridor from east of Des Moines to Grinnell. /rev && .DISCUSSION.../Tonight through Monday/ Issued at 235 PM CST Mon Feb 17 2020 Main Points Wintry precipitation still anticipated over north central Iowa late this afternoon and evening, which could lead to some travel impacts. Confidence in snow totals is quite low due to the potential for mixed precipitation types and near to above freezing surface temperatures. Cooler conditions through the middle of the week with perhaps some light snow in western Iowa on Wednesday. Warming trend follows to end of the week as highs return to the 30s and 40s by the weekend. Pattern looks more active late weekend into next weekend which could bring more chances for rain/snow to the region. Discussion Primarily zonal upper level pattern undergoes amplification through tonight as a trough digs into the upper Plains. Broad warm air advection and upper level forcing has spurred light precipitation over the state today, mainly near and ahead of a cold front nosing into western Iowa. As of 20z RAP analysis has the surface wet bulb zero line near the Minnesota border, although this may be a bit aggressive compared to surface obs. Strong consensus amongst observational data sets that the max wet bulb aloft is greater than +1C over the entire area, so at the very least low to mid level theta-e advection has been warm enough to support mostly rain so far today. Hi-res model guidance remains bullish on the development of a tight mesoscale snow band across far northern Iowa later this afternoon into early evening. Current setup is favorable given low static stability and some CI evident in the folded theta-e contours on cross-sections. Near freezing wet bulb temps and drier air aloft bring possible p-types into question. Strong, concentrated lift within a well organized mesoband could provide enough dynamic cooling to support snow, but near to above freezing surface temps would help mitigate impacts and result in low SLRs. GOES infrared imagery also shows pockets of cloud tops warmer than -10C, suggesting a lack of ice introduction in some areas. Thus some uncertainty still remains as to how the next few hours will evolve within the advisory area, and may just end up with a mixed bag of wintry precip and limited snow accumulations. Temperatures cool below freezing as the cold front swings through, but precipitation wanes shortly after and thus limiting the window for additional accumulating snowfall. Further south light rain is possible until the front swings through late this afternoon and evening. Cannot rule out a few rumbles of thunder and some small hail/graupel with MUCAPE progged between 50-100 J/kg. Beyond tonight the forecast turns cooler through the middle of the week. Next precip chances clip western Iowa on Wednesday as a shortwave trough digs south out of the Canadian prairies. Upper level forcing is not overly robust with this system and moisture is marginal, so not expecting much more than just some light snow at this time. Cold 1045mb surface high settles into the state Wednesday night. Clearing skies and light winds will lead to optimal conditions for raditional cooling, particularly in north central Iowa where a more widespread snow pack should exist and help temperatures fall off into the teens below zero. Temperatures to the south will not be quite as cold. Southerly flow and a gradual warm up for the latter half of the week as low amplitude upper level ridging builds over the region. Highs return to the 30s and 40s, possibly pushing 50 degrees for parts of southern Iowa on Saturday. Closed low over the southwest US swings east beneath the ridge by Sunday, although the track of the low remains quite uncertain. The more northerly GFS would bring rain/snow chances into at least the southern half of the state, whereas the Euro prefers a more southerly track and is mostly dry for the area. Ensemble guidance sheds little light on the most probable solution with a fair split between wet/dry. Pattern evolution into the middle of next week looks quite active as all models develop a large trough over the western states. && .AVIATION.../For the 00Z TAFS through 00Z Tuesday evening/ Issued at 551 PM CST Mon Feb 17 2020 Conditions continue to worsen north sites at KMCW/KALO and briefly at KFOD for the next 2 to 3 hours. Southeast sees potential for some fog through 9 pm. Overall, IFR cigs will give way to MVFR and then VFR conditions aft 04z northwest at KFOD and in the southeast/east aft 10-14z. Lower visby continues with 1/4sm at KMCW and 1/2 to 2sm possible at KALO, KDSM, and KOTM next 3 to 5 hours. Northwest winds increasing to 15 to 20kts gust 28kt aft 02z northwest progressing southeast through 12z. /rev && .DMX WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until 9 PM CST this evening for IAZ006- 007-016-017-025>028. && $$ UPDATE...REV DISCUSSION...Martin AVIATION...REV
Area Forecast Discussion
National Weather Service Grand Rapids MI
635 PM EST Mon Feb 17 2020 LATEST UPDATE... Aviation .SYNOPSIS... Issued at 330 PM EST Mon Feb 17 2020 - Snow and rain tonight - Lengthy stretch of dry weather starts Tuesday - Brief shot of colder air mid week - Late week warm up with sunshine && .DISCUSSION...(This evening through next Monday) Issued at 330 PM EST Mon Feb 17 2020 -- Snow and rain tonight -- No big changes to the going forecast. Snow or a mix begins late this afternoon/early this evening and ends late tonight or around daybreak. The snow will transition to rain/drizzle near and south of I-96 toward midnight, but not before a inch or two of wet slushy snow coats the roads this evening. Precipitation stays mainly all snow tonight north of M-46, with highest accumulations of 3 to 5 inches expected near and north of Route 10, particularly east of Highway 131 around Reed City and Clare. Winter Weather Advisory will remain in effect for all areas since some travel impacts are likely areawide, even where the lower accumulations are forecast. Another issue is that the more rural dirt and side roads currently packed with snow will be icy even from rain. This is a classic wet-bulb/evaporative cooling event this evening for srn Lwr MI, where incoming area of rain becomes mostly wet snow overhead as it falls into a dry air mass and cools the thermal profile below freezing. Sfc dew points are creeping up, but are still only in the lower to mid 20s. Latest HRRR suggests dew points will be 28-32 at 03Z during the height of the event with wet bulb zero hgts remaining below 1200 ft north and east of AZO, supporting mostly snow. A few concerns: While the dry air will promote wet-bulbing, it could also help to limit the amount of precip we see. In fact QPF amounts have decreased southeast of GRR in some of the the latest guidance due to the feed of dry air from the east. Another concern is that the precipitation upstream is not totally solid and there`s some gaps over nrn Il... inbetween the area of precip over central Il and the snow over WI. Lighter and less widespread precip could make wet-bulbing less efficient and may lead to more rain than snow, especially over the sw corner of the cwfa. -- Lengthy stretch of dry weather starts Tuesday -- Guidance has been consistent in showing mostly dry weather from Tuesday into next weekend as split flow pattern develops and we`re inbetween the two branches of the jet. Little to no lake effect is anticipated mid week as the colder air comes in since a large/dry sfc high of around 1045 mb will dominate much of the nrn U.S.. -- Brief shot of colder air mid week -- Single digit lows are likely on Wednesday and Thursday nights under the sfc high. Daytime highs on Wed and Thur will be only in the lower to mid 20s. -- Late week warm up with sunshine -- Quick shift toward milder weather occurs late in the week as the sfc high drifts toward the Mid Atlantic. Southwesterly return flow helps H8 temps rebound from -15 to -20C Thursday to 0 to +5C by Saturday. Highs near 40 or in the 40s look likely for the weekend with strong indications of sunshine... especially Fri/Sat. Southwest winds will be brisk however and that will make it feel cooler. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 635 PM EST Mon Feb 17 2020 Widespread IFR conditions will prevail overnight and then slow improvement can be expected Tuesday morning with MVFR conditons by 15Z. Winds will be southeast this evening with some gusts over 20 knots. Winds will go west overnight and northwest on Tuesday with some gusts over 20 knots. && .MARINE... Issued at 330 PM EST Mon Feb 17 2020 Northwest winds to 30 knots and waves 4 to 7 feet are expected to develop very late tonight after the sfc low tracks through, so Small Craft Advisories are in effect. We have some ice in the nearshore area now, which will act as a buffer for beach erosion. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...Winter Weather Advisory until 10 PM EST this evening for MIZ064- 071-072. Winter Weather Advisory until 1 AM EST Tuesday for MIZ050>052- 056>059-065>067-073-074. Winter Weather Advisory until 10 AM EST Tuesday for MIZ037>040- 043>046. LM...Small Craft Advisory from 4 AM Tuesday to 11 AM EST Wednesday for LMZ844>849. && $$ SYNOPSIS...Meade DISCUSSION...Meade AVIATION...Ostuno MARINE...Meade
National Weather Service Wilmington OH
938 PM EST Mon Feb 17 2020 .SYNOPSIS... A low pressure system will approach the region tonight and a cold front will move through the area on Tuesday. High pressure will then build back into the region for Wednesday and the rest of the week. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... Showers are moving across west central Ohio and will continue to do so over the next few hours before heading off to the east. Forecast become more uncertain south of that area. Low level jet and associated axis of moisture transport will translate across the region overnight. However it appears that showers will be scattered to perhaps numerous and on the light side. Recent HRRR and RAP runs have been trending drier. Temperatures are likely near their lows for the night with slowly rising readings through the overnight hours. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/... Cold front will be located from northwest Ohio back through central Kentucky at the beginning of the period. A second wave of showers will spread across areas south and east of I-71 during the morning. The front will push through the region during the morning hours, lead to the a non- diurnal temperature trend. Highs in the northwest could be shortly after sunrise, while the southeast they could be closer to mid day. As the front crosses the fa, it should bring an end to the rain. Another strong high pressure system will begin to build in Tuesday night. Right now it looks like it will bring clearing skies. Lows Tuesday night will be back around normal, ranging generally in the mid 20s. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... On Wednesday morning, a cold front will be moving well east of the region, exiting the mid-Atlantic coast. Deep-layer westerly flow will keep a pseudo-zonal pattern over the Ohio Valley, with a relatively dry air mass in place over the region. Surface high pressure is expected to be centered over North Dakota on Wednesday, gradually moving southeast, and expected to envelop the Ohio Valley from late Thursday through Saturday evening. The cold advection pattern in the boundary layer will be well established at the beginning of the extended forecast period, bringing cooling temperatures through Thursday night. Also, additional reinforcement of cold air is expected to arrive on Thursday morning, as another cold front moves into the region from north to south. This front is unlikely to produce precipitation, but in association with an upper level trough moving through at around the same time, there will likely be an increase in cloud cover on Thursday. An even colder and drier air mass, associated with the approaching surface high, will move over the region behind the front. This will bring the chance for the coldest temperatures of the week on Friday morning, with clear skies and winds becoming light -- all within an exceptionally dry air mass. Min temps on Friday morning are expected to be in the teens. After the center of the high has passed through the region on Friday, a gradual shift to rising heights and southerly boundary layer flow will take place. This will lead to gradually warming conditions going into the weekend. Overall confidence remains relatively high with the large-scale forecast features, at least through Sunday. Uncertainty becomes a little bit more of an issue with regards to trough development / surface cyclogenesis occurring on Sunday over the southern plains, then moving eastward into the lower/middle Mississippi Valley region on Monday. This system appears like it will eventually spread precipitation into the Ohio Valley at some point late in the extended forecast period, but PoPs will be kept at 20-30 percent at this distance in the forecast. && .AVIATION /03Z TUESDAY THROUGH SATURDAY/... VFR conditions will persist through the early part of the TAF period with winds veering to the south and increasing slightly. As a low level jet translates across the region, there will be a brief period of low level wind shear at most sites overnight. Rain will spread across the region after 06Z, and while it does not look particularly heavy, it will moisten the low levels. This will result in MVFR ceilings developing and then fairly quickly falling to IFR region wide. Some visibility restrictions will also occur with the low ceilings, at least until a cold front passes on Tuesday morning. Once this occurs, visibilities will improve first. Then expect ceilings to lift to MVFR with some breaks in this lower deck. There could be some further improvement in ceilings late in the period, mainly in the Cincinnati area. OUTLOOK...MVFR ceilings will linger into Tuesday night. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...Novak/Sites NEAR TERM... SHORT TERM...Sites LONG TERM...Hatzos AVIATION...
National Weather Service Jackson KY
1013 PM EST Mon Feb 17 2020 .UPDATE... Issued at 1013 PM EST MON FEB 17 2020 Decided to go ahead and stick with earlier trend of slowing down precipitation onset and not having rain entering forecast area until around 12Z, which is about 3 hours earlier then day shift forecast. Of note, the departing dayshift forecast did mention that it may be necessary to slow down precip onset tonight due to large amount of dry air that is currently in place. Ingested the latest obs into the forecast grids to establish new trends. Updated zone forecast text product has been issued. UPDATE Issued at 636 PM EST MON FEB 17 2020 The 18Z run of model data has suggested that precipitation onset will be a few hours slower than previously forecast. With the latest CONSHORT, NAM12, GFS, and HRRR models all suggesting a slower onset, decided to go ahead and update the forecast to reflect this new timing. This supports the idea that dry air that is currently in place could hinder the eastward progression precip in our area and the ability of said precip to reach the ground before evaporating. Also ingested the latest obs into the forecast grids to establish new trends in the very near term. && .SHORT TERM...(This evening through Tuesday night) Issued at 353 PM EST MON FEB 17 2020 The current surface analysis as of 20Z features high pressure over the Northeast retreating east. To the west, crossing the central Plains is the next low pressure system developing and shifting east. This feature will begin to move into the OH Valley tonight into tomorrow morning. The one forecast challenge setting up for this system is the dry surface layer. Dew point depressions across the area are on the order of 15 to 20 degrees. This will make it difficult for the boundary layer to saturate. Thus, have lowered the pops at onset and brought the bulk of the measurable rainfall after 08Z. Due to this tonight, there will likely be some ridge to valley temperature differences as cloud cover will likely not be thick enough for significant insulation. Have adjusted the ridge and valley temps for lows tonight according to this. By 12Z tomorrow morning, ceilings will finally lower with the column finally saturating. 850MB winds will be at 40 to 50 knots with the low level jet impacting the area from the southwest. By Tuesday morning, a low level inversion setting up will keep the stronger winds from mixing to the surface but, still some 20 to 30 mph gusts are not out of the question. As well, give weak instability, have gone with showers across the area but not expecting thunder at this time. Through the day, southwest flow will continue with highs reaching into the mid 50s with the cold front passing through in the afternoon. The air mass moving in behind this front will bring clearing skies with temps dropping into the upper 20s for lows. The bulk of the moisture will exit the area before the colder air changes the precip to snow with the exception of the higher elevations. Overall, this will lead to more normal values for lows Tuesday night. .LONG TERM...(Wednesday through Monday) Issued at 320 PM EST MON FEB 17 2020 Models are in good agreement with features aloft through the period. Interestingly, noticed that the 12Z solution of the ECMWF trended towards the GFS for the last 36 hours of the extended, where some significant differences had previously existed. The pattern is best described as a mean zonal flow regime with two main features of interest, the first a northern stream positively tilted trough that will drop southeast across the eastern CONUS Thu/Fri. The second feature will be a southern stream trough or low that will lift out of the far southwest, push through the Great Plains and into the Tennessee/Ohio valley regions by the end of the forecast. At the surface, strong Canadian high pressure will build into the eastern half of the nation, tracking from the Northern Plains to the Appalachians during the first 72 hours of the period. A disturbance will develop over the far southeast Thu/Fri, a weak reflection of the aforementioned positively tilted trough. This disturbance will produce generally light, but widespread precipitation from the Tennesseee Valley southward. It appears our area remains dry, though some solutions do suggest a slight chance of precipitation along the KY/TN state line. Otherwise mid, and especially high level clouds, will blanket the much of the region. Ridging aloft and surface high pressure will then transit the Ohio and Tennessee valleys. Thereafter, a storm system approaches from the west by the end of the weekend or start of the following week. Sensible weather features generally dry weather through the period. With Canadian high pressure ushering in dry/colder air into the region and high pressure centered over the central Ohio Valley Friday and Saturday morning, expect temps to run below normal for that time frame. Temps look quite cold (into the teens) by Friday morning and while closer to normal, still drop to around 20, or mid 20s Saturday morning. A few locations in our typically colder eastern valley areas could slide into the mid teens again Saturday morning. Thereafter, temps moderate through to the end of the forecast with an increase in clouds and the threat of precipitation as our next weather maker approaches from the west. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) ISSUED AT 639 PM EST MON FEB 17 2020 Expect VFR conditions to begin the TAF period with generally light and variable winds. Winds will slowly begin to increase out of the south through tonight and into tomorrow morning before shifting to the southwest. Ceilings will begin to drop tonight as the cold front approaches from the west. Expect some below IFR cigs by 12 to 13Z with rain dropping vis to IFR conditions as well. These conditions will then persist through the rest of the TAF period. The one thing in question at this point, is how fast will this drop in conditions occur. Dry air in place, may hinder the drop in cigs and vis pushing the occurrence back a few more hours, which is now reflected in the TAF forecast. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...AR SHORT TERM...SHALLENBERGER LONG TERM...RAY AVIATION...AR
National Weather Service Charleston WV
857 PM EST Mon Feb 17 2020 .SYNOPSIS... Damp Tuesday with rain developing ahead of a cold front that will arrive late Tuesday. Colder and drier for the end of the week with high pressure. && .NEAR TERM /THROUGH TUESDAY/... As of 847 PM Monday... Have made a couple of changes to the inherited forecast, including adjusting hourly temps and overnight lows for tonight. Many of the smaller valleys across the lowlands have already dropped into the low to mid 40s while area ASOS/AWOS observation sites at higher airport elevations remain around 50 degrees. As such, I`ve trended the overall temp forecast to account for this. Official lows tonight may occur late evening and then slowly rise closer to sunrise as warm air advection strengthens (especially so for locations above 2.5kft). Also slowed down arrival and departure of precip for Tuesday. There is still quite a thick and stout dry layer in the lower levels tonight that will take awhile to overcome. Last several runs of the HRRR have indicated a slower development and associated progression of precip on Tuesday with time-lagged models also indicating a greater likelihood of delayed arrival. As of 200 PM Monday... High cirrus passing through the Central Appalachians this afternoon hasn`t put a stop to southerly flow and warm air advection from taking place. Generally went a few degrees warmer than guidance for today based on how warm we already are at the time of this issuance, per local and regional observations. However, clouds will begin to lower and thicken this evening as a warm front lifts northward, precluding the next disturbance ejecting out of the midwest overnight. PWATs will be on the increase as well overnight, setting up for a wash out of a day tomorrow. The rain shield will mark the location of the cold front which will cross from west to east through the day Tuesday, making it over the mountains by the evening. Thermal gradient sets up overnight tonight with a cold wedge along the spine of the Appalachians. Embedded light POPs within the wedge may allow for a slight chance of light snow showers around midnight tonight, then transitioning back into snow as 850mb temperatures rebound above freezing. Opted to delay the onset of rain in our northwestern zones late tonight as moisture overcomes dry air established in the low levels of the atmosphere from today. This coincided well with the thinking of our neighboring offices, so as it currently stands I have rain entering into Perry County during the predawn hours then engulfing the forecast area by the morning rush hour. May have gone a bit overzealous with POPs in the southern coalfields for Tuesday morning, but I do expect categorical POPs by the afternoon as the front continues its pursuit eastward. Precip winds down heading into the end of the near term, with colder air right on its tail. It won`t be fast enough to inflict a changeover to frozen precipitation in the lowlands, but perhaps over the mountains late Tuesday night. && .SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/... As of 215 PM Monday... Cold front slips southeast Tuesday night with drier and colder air advecting in from the northwest for Wednesday. Model soundings indicate some low level moisture may linger beneath a developing subsidence inversion which may keep some clouds around through the day. An upper level system will drop south through the Plains, eventually interacting with the old frontal boundary draped along the Gulf Coast Thursday and Thursday night. This will help to induce surface cyclogenesis which will track east off the Southeast coast. This will likely just impact the area with some mid and high level clouds as a strong surface high traverses down the MS River valley. Temperatures will start mild and end below average Thursday and Thursday night. && .LONG TERM /FRIDAY THROUGH MONDAY/... As of 220 PM Monday... Aforementioned surface high will make its way toward our region Friday and Saturday while weakening. An abundance of dry air through the column will likely mean quite a bit of sunshine for a change. This won`t last as the next system approaches from the west Sunday night and Monday with rain chances increasing. Temperatures will moderate back above normal for the weekend. && .AVIATION /02Z TUESDAY THROUGH SATURDAY/... As of 637 PM Monday... VFR nearly areawide for most of tonight, but rapidly deteriorating flight rules during the day Tuesday. Mid level cloud deck currently moving east across the area with a lack of low level moisture precluding any impacts from CIGs tonight. By late tonight (and moreso after sunrise Tues), SSErly llvl flow will promote more significant moisture advection with rapidly lowering CIGs from VFR to MVFR. Numerous SHRA to even widespread RA should develop and spread from west to east Tues morning, aiding in a further deterioration of flight rules to IFR at times. Precip should end from NW to SE in the afternoon as a sfc front moves through the area, however some -RADZ may persist even into the late hrs of the TAF period from KBKW to KEKN (with improving flight rules elsewhere). Some variable winds early in the TAF period should become more SErly overnight...strongest at KBKW/KEKN/KCRW (sustained 5 to 15 kts and gusty at times) and closer to 5 to 10 kts elsewhere. Winds veer more SWrly during the daytime hours Tues and eventually NWrly after FROPA mid/late afternoon. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z WEDNESDAY... FORECAST CONFIDENCE: High tonight. Medium Tues. ALTERNATE SCENARIOS: Non-convective LLWS may need to be included in future TAF pkgs for the overnight hours of tonight. Timing of arrival of precip and lower flight rules on Tues is a bit uncertain, but may occur sooner than currently forecast. EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY OF WFO FORECAST TO AVAILABLE MODEL INFORMATION: H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS. L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. DATE TUE UTC 1HRLY 00 01 02 03 04 05 06 07 08 09 10 11 EST 1HRLY 19 20 21 22 23 00 01 02 03 04 05 06 CRW CONSISTENCY H H H H H H H H H H H H HTS CONSISTENCY H H H H H H H H H H H H BKW CONSISTENCY H H H H H H H H H H H H EKN CONSISTENCY H H H H H H H H H H H H PKB CONSISTENCY H H H H H H H H H H H H CKB CONSISTENCY H H H H H H H H H H H H AFTER 00Z WEDNESDAY... No widespread IFR conditions expected at this time. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...None. OH...None. KY...None. VA...None. && $$ SYNOPSIS...30/MEK/RQH NEAR TERM...RQH/MEK SHORT TERM...30 LONG TERM...30 AVIATION...RQH