Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/06/18

See below for an aviation forecast discussion for the 00Z TAFs.

&& .SHORT TERM...(This Evening through Tuesday Afternoon) Issued at 329 PM CST Mon Feb 5 2018 A pressure surge/cold push along with surface heating has brought some lower clouds to the area along with some flurries showing up on radar. Thus, added in isold flurries across the east for the rest of the afternoon. Otherwise, the Arctic high pressure area to our northwest will settle over the region tonight with skies clearing and winds going light. This will bring a very cold overnight with lows mainly in the single digits below zero with some teens below zero in the James Valley. The models then show a short wave trough dropping in from the northwest on Tuesday spreading clouds across the cwa along with some light snow. Expect areas of light snow to spread from west to east with only a few tenths of an inch accumulation possible by evening. Warmer air advecting in on south winds will bring highs in the teens and 20s by late afternoon. .LONG TERM...(Tuesday Evening through Monday) Issued at 329 PM CST Mon Feb 5 2018 First look at Wednesday morning, decided to lower temperatures below blended guidance. Weak feature is mostly moved east and clouds should also be clearing west of the James valley after midnight. Low level flow has a weak gradient but the center of the high is still up in northwest North Dakota, but migrating towards the CWA. Thus, given recent snow cover to at least partially mask the radiation of the earth, readings should crash with loss of cloud cover and an already cold start. The long range pattern will be dominated by the upper trough across eastern North America with generally northwest flow aloft through about the end of the work week, though guidance diverges after that and confidence drops on conditions for next weekend. That said, there will be plenty of weather as guidance parks a deep layer of stratus across the forecast area, mainly from northwest to southeast South Dakota, impacting the western and central CWA. Not really much of a wave aloft, but off and on weak isentropic ascent or warm advection aloft could be the impetus for light snow generation despite lift generally less than 10 microbars. Low level pattern features sprawling high pressure to the north and an increasing tightening pressure gradient to the southwest, but low level flow over our CWA during this time is also weak and winds will likely not be an issue. As for temperatures, we remain mainly on the cold side of the Arctic front, with an increasing thermal gradient from southwest to northeast Thursday/Friday and a wobble southwards. Thus, temperatures will continue below average through the end of the work week and likely into the weekend. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday Evening) Issued at 625 PM CST Mon Feb 5 2018 Stratus/strato-cu has dissipated and all four terminals should be good VFR through at least 12Z Tuesday. Throughout the day on Tuesday, low/mid-level (VFR-MVFR) cloudiness will spread/develop east over the forecast area and increase in coverage. RAP model soundings in BUFKIT do show full saturation occurring within the dendritic growth zone in tandem with enough synoptic scale lift to produce some (MVFR-IFR) light snow on Tuesday, earlier in the day for KMBG/KPIR and later in the day for KABR/KATY. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. && $$ UPDATE...Dorn SHORT TERM...Mohr LONG TERM...Connelly AVIATION...Dorn
Area Forecast Discussion...UPDATED
National Weather Service Corpus Christi TX
915 PM CST Mon Feb 5 2018 .DISCUSSION...It appears that the coastal trough over the coastal waters has weakened and wind flow along the coast has shifted to more of an easterly direction. Dewpoint temperatures in the upper 60s over the offshore waters will continue to move toward the coast as the coastal trough axis approaches the coastline. Although there are no observations in the near shore waters, suspect there is dense fog in the region similar to the what is observed off the coast of Matagorda Bay. Visibilities have lowered along the coast and expect this will continue through the night. See Marine section for Dense Fog Advisory. Looking at latest RAP model along 00Z NAM, it looks like the trough axis will continue to move inland during the day on Tuesday. This will lead to slightly warmer temperatures over inland coastal plains and raised max temps about a category. Also, removed mention of drizzle and fog in the afternoon. Northern Brush Country could see fog linger into the early afternoon. && .MARINE...With coastal trough approaching the coast during the overnight hours, warm moist air will continue to move across the cooler shelf waters. Dense fog over the near shore waters should move into the bays later this evening and continue through the morning hours. Will issue Dense Fog Advisory for bays and near shore waters until 18Z Tuesday. && .PREVIOUS DISCUSSION... /Issued 547 PM CST Mon Feb 5 2018/ DISCUSSION...See Aviation section for 00Z TAFs. AVIATION...MVFR ceilings will continue to prevail across the region early this evening except along the immediate coast. The higher resolution models depict the coastal trough, over the offshore waters of the middle Texas coast, will be slow to move inland during the afternoon hours on Tuesday. Expect ceilings will fall to IFR by mid evening over the coastal plains and after midnight over the Brush Country. Aviation conditions will further deteriorate around 06Z over the coastal plains to LIFR in fog and light drizzle. LIFR ceilings expected to reach LRD area around daybreak. Vsbys are expected to improve from 15-16Z but IFR ceilings will linger into the afternoon. As the coastal trough moves inland during the afternoon, vsbys will improve but expect IFR ceilings will remain over the coastal plains with MVFR ceilings over the Brush Country. && .PRELIMINARY POINT TEMPS/POPS... Corpus Christi 59 72 53 57 45 / 20 20 40 70 40 Victoria 56 70 45 49 41 / 20 30 50 60 20 Laredo 59 71 52 56 43 / 20 30 30 50 30 Alice 58 74 52 56 42 / 20 30 40 70 40 Rockport 58 66 51 55 45 / 20 20 40 70 40 Cotulla 56 64 48 52 41 / 20 30 30 60 10 Kingsville 60 76 57 61 43 / 20 20 30 70 40 Navy Corpus 59 68 55 59 46 / 20 20 30 70 40 && .CRP WATCHES/WARNINGS/ADVISORIES... TX...None. GM...Dense Fog Advisory until noon CST Tuesday For the following zones: Bays and Waterways from Baffin Bay to Port Aransas... Bays and Waterways from Port Aransas to Port O`Connor... Coastal waters from Baffin Bay to Port Aransas out 20 NM... Coastal waters from Port Aransas to Matagorda Ship Channel out 20 NM. && $$ TMT/89...SHORT TERM
Area Forecast Discussion
National Weather Service Cheyenne WY
630 PM MST Mon Feb 5 2018 .UPDATE... Issued at 625 PM MST Mon Feb 5 2018 Allowed all winter headlines to expire on time at 5PM and 6PM. Looks like all the colder cloud tops now are down in Colorado, so most of the energy for producing snow now further south. Will keep an eye on current snow band. This band extends from Harrisburg to Chugwater to Wheatland this evening. But it is moving, so heavy snow accumulations are not likely I think. Updates sent. && .SHORT TERM...(This evening through Wednesday night) Issued at 225 PM MST Mon Feb 5 2018 Tonight...Expecting instability type banded snow showers to continue into the evening hours, most numerous along the southern portion of I-25 where the baroclinic band resides along the cold front. Snow showers expected to decrease in coverage after midnight as the best lift moves into Colorado. Tuesday...Much less coverage of snow showers as low and mid level moisture decreases with less lift. However, expect orographic snow showers to continue over our Snowy and Sierra Madre Ranges with some moisture over there. 700 mb temperatures near -10 Celsius will yield high temperatures mainly in the 30s. Tuesday night...Orographic snow showers will decrease in coverage across our Snowy and Sierra Madre Ranges as moisture wanes. Should still see plenty of middle and high clouds streaming overhead, however, based on model projections. Wednesday...Moderate warming trend expected as heights and thicknesses rise. Breezy to windy west of I-25 based on low and mid level gradients. .LONG TERM...(Thursday through Monday) Issued at 225 PM MST Mon Feb 5 2018 Northwest flow aloft Thursday will back to the southwest as shortwave energy carves a positively-tilted upper trough over CA/NV by Saturday. A closed upper low forms over southern CA by Sunday morning, ejecting east-northeast across northern AZ/NM Monday. Thursday will be mild and dry with breezy to locally windy conditions along and west of the Laramie Range. High temperatures will be in the 40s to lower 50s. The CAG-CPR 700/850mb gradients increase to 55-60 meters Thursday night and early Friday ahead an approaching cold front from the north. 700mb wind rise to 50-55 kt between Laramie and Rawlins by Friday morning. High Wind headlines may be needed at that time. Light snow gradually spreads north to south late Thursday night through Friday. The cold front will push southwest to near the CO border Friday night and early Saturday morning. Widespread snow will continue through Saturday afternoon, tapering Saturday evening. High temperatures Saturday will range from the upper teens north to upper 20s south. The GFS shows a wide swath of high QPF (near a 1/2 inch) along and south of a Rawlins to Sidney line, while the ECMWF is lighter on its amounts. Should the GFS scenario pan out, we could be dealing with several inches of snow. Still have time to iron out the details with the model differences, but certainly something that bears watching the next couple of days. The front lifts northeast as a warm front Sunday with drier conditions and slowly moderating temperatures into early next week. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 625 PM MST Mon Feb 5 2018 IFR conditions in snow for areas along and south of a line from Sidney to Wheatlnd to include KCYS. Latest HRRR guidance holds IFR conditions here at KCYS through early tomorrow morning (10Z). Will continue to monitor. && .FIRE WEATHER... Issued at 225 PM MST Mon Feb 5 2018 No concerns with chilly temperatures and minimum humidities above critical thresholds. Most areas will receive accumulating snow this afternoon and tonight and again Friday through Saturday. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None. && $$ UPDATE...GCC SHORT TERM...RUBIN LONG TERM...MAJ AVIATION...GCC FIRE WEATHER...RUBIN
National Weather Service Kansas City/Pleasant Hill MO
936 PM CST Mon Feb 5 2018 .Update... Issued at 935 PM CST MON FEB 5 2018 With the wintry precipitation moving out of the forecast area, the Winter Weather Advisory has been allowed to expire. Our focus now turns to the next system, which is currently developing out near the Four Corners. Models continue to indicate the best chances for snow are across northern MO and northern KS, including the north- side of the KC Metro area. Most likely snow totals are 1-3 inches, but uncertainty with storm track and snow amounts still exists. Additionally, the KEAX WSR-88D will remain down during this winter event. Surrounding radars (MCI, KTWX, KOAX, KDMX, KLSX, KSGF, and KDVN) will be available though. For more information, please visit && .Discussion... Issued at 229 PM CST MON FEB 5 2018 Weak wave currently moving through the area with sporadic reports if -FZDZ received across the area. Quick look at both NAM and RAP fcst soundings should suggest enough saturation in the snow growth region to result in all snow, however have added a patchy FZDZ mention in for this afternoon`s fcst. Otherwise, this feature should have little impact on the area with maybe a few tenths of an inch of new snow possible across our northern most fcst zones. This system should exit stage right by 03z, setting the stage for what should be another chilly night thanks to yesterday`s snowfall and a short duration clearing trend. Couple those factors with the fact that we`re sitting at 20 degrees at the office this afternoon, overnight lows in the low to mid single digits again seem plausible. This leads us into tomorrow`s well-advertised storm system. What a difference from last week`s model presentation, which originally showed a leeside low lifting north from the southern High Plains, with a cold front and associated frontogenesis max approaching from north, which were to both act as additional forcing mechanisms for precip production. Now, models show no hint of a leeside low, with all forcing for this feature resulting from midlevel frontogenesis and weak synoptic scale forcing from a passing open wave. Considering temperatures will be more than cold enough to support all snow, the main factor influencing today`s fcst involves a northward shift of the heaviest precip axis, which now appears will occur north of the KC metro. In fact, a pretty tight snowfall gradient may occur across the metro, with the northland possibly seeing 1-3" totals, while areas south of the Missouri River struggle to reach an inch. If one were to believe the NAM, little if any snowfall will occur south of the Missouri Rvr. Even the GFS has trended north this afternoon, however it still remains the most bullish on snow totals for the metro. Considering this trend, along with the fact that forcing as a whole just doesn`t appear all that strong, have taken the liberty of refining snow totals this afternoon, mainly based on these latest trends. It still stands to reason that a swath of 2-4" could occur north of the metro, maybe from the St. Joe area northeast through Kirksville, however, amounts south of the river look to be lower than previously thought. The other factor that`s worth noting is the fact that this feature will likely arrive later than previous fcsts had suggested, with snow moving into the KC metro after 18z, with all activity pretty much off to our east by 06z at the latest. Considering the timing differences, the AM commute should get along just fine, with conditions possibly worsening through the evening commute. That said however, heaviest snows may hold off long enough to prevent too many problems for tomorrow`s evening rush, so lets keep our fingers crossed. Beyond Tuesday`s system, broad northwest flow looks to dominate through the end of the week with the next chance for precip looking to arrive on Friday when another cold front approaches from the north. Precip will likely grow upscale Friday ngt into Saturday as additional energy lifts northeast from the Southern Plains, with current thermal profiles suggesting enough warm air in place to result in mostly rainfall. System to then pass though Saturday night, with cold air settling south and possibly transitioning precip back to snow on Sunday. && .Aviation...(For the 00Z TAFS through 00Z Tuesday Evening) Issued at 548 PM CST MON FEB 5 2018 Light snow, with patches of freezing drizzle have been moving through the area, with the bulk of the snow falling north of HWY 36. This activity will continue to move east, exiting the area around 03Z. Conditions should improve in the next few hours or so behind this system, leaving everyone dry, with mostly clear skies tonight through about dawn. This is when the next system will approach. Light to moderate snow is likely with this system starting in the afternoon and right now, model consensus shows the bulk of the snow will be north of I-70. Low ceilings and visibility will accompany the snow, likely causing MVFR conditions and potentially IFR visibilities. There is uncertainty though where the snow/ no snow line will be, with IXD near that line right now. So for the time being, have kept the snow mention to VCSH there with VFR conditions. Timing and location of snow could still change though, so should have at least a little better of a handle for the next TAF issuance. && .EAX WATCHES/WARNINGS/ADVISORIES... KS...NONE. MO...NONE. && $$ Update...Grana Discussion...32 Aviation...Grana
Area Forecast Discussion
National Weather Service GRAND JUNCTION CO
515 PM MST Mon Feb 5 2018 .SHORT TERM...(Tonight through Tuesday night) Issued at 248 PM MST Mon Feb 5 2018 Scattered snow showers have picked up with daytime heating today across northwestern Colorado in narrow bands of convection just ahead of an approaching trough. The trough advecting colder air into the region will pass northwest to southeast through eastern UT and western Colorado tonight and into Tuesday morning. This system has slowed down about 12 hours from the previous forecast solutions from 24 hours ago. Showers will be possible along this front, so many locations may see rain, snow or a mix of both overnight through Tuesday afternoon. A few lightning pulses have been detected near Juniper Springs today, and this threat will continue through the nighttime hours. As the trough passes through late tonight, a band of precipitation is expected to develop south of I-70 and as far south as the northern San Juans. The HRRR and RAP indicate a secondary band of precip developing toward the early morning hours across the San Juans, which will also bring a chance of precip to the Four Corners valleys for a short window Tuesday morning. Snow amounts are generally expected to be light, with the exception of the advised areas of the central CO mountains and very high elevation spots in the northern San Juans. With this trough`s convective nature, brief whiteout conditions will be possible through Tuesday morning where heavier showers pass through. The atmosphere stabilizes Tuesday evening leaving cooler northwesterly flow in place. .LONG TERM...(Wednesday through Monday) Issued at 248 PM MST Mon Feb 5 2018 Stable conditions continue in northwest flow Wednesday and Thursday with daytime temperatures gradually increasing toward the end of the week as warm air slowly advects into the region at mid levels. A huge divergence in model solutions remains for the weekend - with the GFS much more interesting and dynamic with a split off closed low over the Desert Southwest, the EC keeping the region in NW flow, and the CMC in the middle. The ensemble products as a whole swing a trough through eastern UT and western CO over the weekend, so odds are that somewhere in eastern UT and western CO will see some clouds and precipitation over the weekend. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 515 PM MST Mon Feb 5 2018 The northern and central Colorado mountains will continue to remain obscured in snow showers this evening through Tuesday morning. ILS breakpoints will be reached at KHDN, KEGE, KASE, AND KTEX through 18Z Tuesday with the greatest impact between 09Z and 15Z due to showers and low ceilings/visibility. Elsewhere, scattered showers will bring light precip from time to time through Tuesday morning with BKN to OVC skies and some low ceilings here and there. Conditions expected to improve by midday Tuesday as drier air moves back into the region. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...Winter Weather Advisory until 9 AM MST Tuesday for COZ010-012. Winter Weather Advisory until 5 AM MST Tuesday for COZ004-013. UT...None. && $$ SHORT TERM...JAM LONG TERM...JAM AVIATION...MDA
Area Forecast Discussion
National Weather Service Grand Rapids MI
923 PM EST Mon Feb 5 2018 LATEST UPDATE... Update .SYNOPSIS... Issued at 330 PM EST Mon Feb 5 2018 A quick burst of snow will move across Southern Lower Michigan tonight and this will be enhanced by Lake Michigan. All told, areas along the lake shore and along I-94 west of Battle Creek should see 4 to 6 inches. Meanwhile areas NE of Grand Rapids will see 2-4 inches, while areas toward Mt. Pleasant will only see 1-2 inches. Another round of snow will arrive Tuesday night into Wednesday. Even more snow is expected Thursday night and again Saturday and Saturday night. It will remain cold into early next week with daily highs in the 20s to lower 30s. && .UPDATE... Issued at 924 PM EST Mon Feb 5 2018 It would seem the snow bands we expected to develop have in fact developed but they have not become organized into one coherent snow band. The latest RAP model shows the best lift and convergence just west of Grand Rapids but over time, as the surface trough comes through around midnight, that wills shift that area south and east. There seems to be some directional wind shear in the clouds with the snow bands too and that is not helping the cause for heavier snowfall. As a result I have decreased the expected snowfall into the 1 to 3 inch range. I will leave all headlines as is even so. && .SHORT TERM...(This evening through Wednesday night) Issued at 330 PM EST Mon Feb 5 2018 Will make a couple more tweaks to the current headlines as accums continue to trend a bit higher. Will add Ingham and Jackson Counties to the advisory. Also will end the advisory at 10Z as this is a quick hitter and the snow should be over prior to the morning commute. Coupled upper jet will be squarely over the region later this evening, bringing the steady snow that was over IA and Northern IL into Southern Lower. Snow accums in IA have been in the 4-5 inch range, and since this will be lake enhanced expect at least that amount to occur here. The lift from the upper jet will be strongest over the area south of I-96, so it makes since to include Ingham and Jackson. Areas west of U.S. 131 will also see decent snows largely due to the lake effect. Mean flow early this evening will be about 250, but by late evening it will pivot to 280-290. So this sprays the entire lake shore as the moisture depth is healthy. Highest totals of 4-6 inches are expected south and west of Hart to Freemont to Battle Creek. The advisory buffers this line to the north and east, for a 2- 4 inch accums. The upper jet lifts away quickly, so have the advisory only running until 10Z. The message will be the snow will be over by the morning commute, but untreated roads will still be slick. Weak lake effect is expected behind the system for Tuesday into Tuesday evening. This will remain weak due to high pressure moving in through this period. Another period of snow is expected for Tuesday night into Wednesday that will also be lake enhanced and as a surface low tracks to our SE. Another 1 to 4 inches is expected from this event. .LONG TERM...(Thursday through Monday) Issued at 330 PM EST Mon Feb 5 2018 Several waves of low pressure will bring some impacts to the region during the long term period. Overall confidence is somewhat diminished based on the lack of model run to run continuity. One low amplitude wave is shown to arrive Thursday into Friday. The forcing is forecasted to be relatively weak with this system but it will be a prolonged period of snow. A couple of inches of snow are possible. Right now it looks like mostly minor/moderate impacts from this system. Will maintain high POPs for this event. Another area of low pressure is shown to track up the Ohio Valley for Saturday into Sunday. This system will have some better forcing and will likely tap Gulf Moisture. Thus an increased risk for moderate or better impacts exists. The forecast soundings from the latest GFS suggest a mix is possible for far southern lower Michigan. The High Res Euro is colder with this system. With the low tracking up the Ohio Valley...will keep the precipitation type as snow at this point. Will need to monitor trends closely. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 644 PM EST Mon Feb 5 2018 IFR conditions in snow is expected at all of the GRR TAF sites between 01z and 06z, with AZO and GRR likely to have the lowest conditions due to a lake enhanced snow band over those two sites. That should move out in the 06z to 09z time frame but light system snow may continue till 12z or so. Some lake effect snow is possible at MKG, GRR and AZO till around 18z . From 12z to 18z I may not have the visibility low enough for the heaviest snow showers but the forecast should be good for the prevailing conditions. Ceilings should mostly be MVFR during the daylight hours of Tuesday. && .HYDROLOGY... Issued at 1243 PM EST Mon Feb 5 2018 Quite a bit of fluctuation was showing up in gauge reports from Portland and Eagle this morning with downstream sites showing falls. This suggested an ice jam may have formed somewhere between Ionia and Portland on the Grand River. Coordination with Ionia County and Clinton County Emergency Management revealed that Portland`s erratic readings are a bit higher than actual levels. A lot of ice is jammed up around Portland, where river levels are near bankfull upstream of the gauge. Eagle on the other hand, was spot on with observed levels that spiked overnight into the early morning as a result of the jam near Portland. Standing water was reported in low lying farmland adjacent to the Looking Glass River, but was having minimal impact. Recent observations show the river has peaked for the time being and is beginning to recede again. Ice seem to have stabilized as water flows beneath it. Forecasts have not changed in regard to the cold air and multiple rounds of snowfall through the week. Snowfall will not have an immediate impact. However, it will delay that impact to when temperatures warm again and ice is less stable. For now, the most important issue is the continued affects of ice in the event additional ice jams form. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...Winter Weather Advisory until 5 AM EST Tuesday for MIZ037-038- 043-044-050-056>058-064>067-071>074. LM...None. && $$ UPDATE...WDM SYNOPSIS...JK SHORT TERM...JK LONG TERM...MJS AVIATION...WDM HYDROLOGY...JAM
National Weather Service Jackson KY
1058 PM EST Mon Feb 5 2018 .UPDATE... Issued at 1058 PM EST MON FEB 5 2018 With lack of clouds, temperatures continue to drop off across eastern Kentucky. Made another adjustment to the current and low temperatures based off of latest observations, dropping the overnight lows by another 1 to 2 degrees. Still expecting them to level off at some point in the next few hours and start slowly increasing as clouds and precip move nearer to the CWA. Also made sure the dew points and winds were on track with the current conditions. All updates have been published and sent to NDFD/web. A new forecast package was also sent out to reflect the changes in overnight lows and remove evening wording. UPDATE Issued at 914 PM EST MON FEB 5 2018 Quiet evening thus far with mostly clear skies and light winds. Thicker high clouds are just starting to make their way into the northern CWA, with forecast track for precip related to incoming system unchanged thus far. After loading in the latest observations for hourly temps, it was clear that many locations are dropping off as they are not yet being insulated/moderated by the cloud cover. some locations current temps were at or just below the forecasted lows. As such, went in and lowered overnight lows by a few degrees in most locations, then adjusted the diurnal curve so that overnight lows were reached in the next few hours, then moderated and rose slightly through the rest of the night with the incoming clouds and precip, in addition to more southerly flow. Will continue to monitor temp trends and update again as necessary. All changes have been sent to NDFD/web. A new forecast package will be sent out in the next hour to remove evening wording and reflect the slight chance in low temperatures. && .SHORT TERM...(This evening through Tuesday night) Issued at 340 PM EST MON FEB 5 2018 20z sfc analysis shows weakening high pressure over Kentucky and this has finally cleared out nearly all the lower clouds. Sunshine filtered through the present high clouds is helping to raise temperatures into the lower 30s for the southern half of the CWA and upper 20s further north. Do not expect the highs this afternoon and limited sunshine to raise the road temperatures above freezing going into the night, though. Meanwhile, dewpoints are in the mid to upper teens with light and variable winds. The models are in good agreement aloft with this unsettled pattern of yet another weak shortwave passing quickly through the Ohio Valley followed by a larger trough approaching for mid week. The weaker feature passes through tonight skirting along the Ohio River, while a larger trough moves into the region Tuesday night. Large scale southwest flow develops along with that latter wave as the pattern tilts. Given the model symmetry have followed a blended solution with a strong lean on the higher resolution HRRR and NAM12 for weather details. The latest bout of light winter pcpn arrives tonight in the form of a wintry mix as a weak front moves through. The pcpn arrives after midnight and passes through from northwest to southeast before clearing out temporarily by mid morning Tuesday. Although just a couple of hundredths of an inch of pcpn are possible from this it does look like ice crystals will be lacking aloft resulting in freezing drizzle as the main p-type. Some seeding of ice crystals from higher clouds appears likely at the onset for light snow and flurries, but that is gone 4 or 5 am. Road conditions have been an issue that past two mornings and look to again be a concern for Tuesday morning. The threat for freezing drizzle or a mixed bag of light pcpn continues through mid morning Tuesday before the area dries out from west to east. Will issue an SPS to highlight this light wintry mix concern for late tonight into Tuesday morning. Attention will then turn to a more substantial weather maker moving in from the southwest later in the day and continuing into the night. This will be well supplied with deep layer moisture from the Gulf of Mexico. As the sfc low associated with this moves into the Tennessee Valley Tuesday night it will push warmer air into eastern Kentucky along with plenty of rain. However, the northern fringe of this will have a hard time shoving the cold air out of the way and as a result some mixed pcpn in the form of sleet and freezing rain look to be on tap - mainly for locations north of interstate 64 - for a time. By 12z Wednesday, warm air should have overtaken the entire area switching all the pcpn to rain - possibly heavy at times. Used the CONSShort and ShortBlend to initialize the grids with only minor terrain based temperature adjustments tonight and Tuesday night owing to a CAA pattern tonight and increasing moisture Tuesday night. As for PoPs, hit them a bit harder later tonight than they came in from the blend and also moved them in quicker from the southwest on Tuesday afternoon. .LONG TERM...(Wednesday through Monday) Issued at 346 PM EST MON FEB 5 2018 By Wednesday morning, much of the area should see a nice warm nose aloft over them. This will keep precipitation all rain through much of the day. A marginal chance for freezing rain may hold on in northern Fleming county through the morning, but even there temperatures should climb enough by the afternoon, to keep things mainly rain. The main push of rain will come through the morning hours, with rain tapering off into the afternoon as we lose the ice in the clouds. We could see a transition to some drizzle into the evening hours. As temperatures start to cool back below freezing Wednesday evening, the threat for freezing drizzle will return and likely last through the night. Eventually, as the lower levels continue to cool, we may reintroduce ice and may trend towards more flurries after midnight. Either way, potential exists for some slick conditions into Thursday morning. High pressure will then slide east across the region Thursday into Friday, providing a more tranquil, but cool period of weather. Heights will start to build quickly into Friday night and Saturday as a cold front approaches from the northwest. The heights should recover fast enough, that by the time any precipitation reaches us Saturday morning, it should all be in the form of rain. Still some timing differences with respect to when precipitation arrives, but it does look like a period of wet weather will be seen sometime Saturday or Saturday night. GFS keeps the threat of rain going into early the following week, while the ECMWF continues to maintain the cold front pushing on through and conditions drying off as we turn cooler again. Clearly still lots of uncertainty with the late weekend and early next week period, so will stay close to the blended guidance. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) ISSUED AT 701 PM EST MON FEB 5 2018 Mostly clear skies and light and variable winds are currently in place across eastern Kentucky this evening. Another disturbance is expected to push through late tonight, generally between 8 and 15Z. This will result in an increase and lowering of CIGS, with MVFR conditions possible by 9Z. It will also bring in a touch of light pcpn in the form of light snow or freezing drizzle. For now, accumulations look spotty at best so will keep it as VCSH in the TAFs. However, for locations that do see freezing drizzle/rain, expect slick conditions to develop on tarmacs and last into the morning before temps rise above freezing. Precip will end and temps will warm above freezing by mid morning. However, lingering clouds could hover near MVFR through much of the afternoon. Winds will generally remain light and variable through the period. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...JMW SHORT TERM...GREIF LONG TERM...KAS AVIATION...JMW
Area Forecast Discussion
National Weather Service San Angelo TX
910 PM CST Mon Feb 5 2018 .UPDATE... Quick update on the forecast for late tonight, Tuesday, and Tuesday Night. Latest HRRR and NAM both had a bigger push on the cold air that before, with temperatures dropping during the afternoon. The 18Z GFS trended that direction as well. With that in mind, brought the cold air in a little faster on Tuesday. Highs on Tuesday will likely come a little earlier in the day which will have some effect on forecast highs, but will have a bigger effect on forecast hourly temperatures behind the front. Portions of the Big Country may not be much above freezing for a big part of the afternoon. This faster push also has an affect on the chances of freezing precipitation across the Big Country, including Abilene and Sweetwater. Brought the mention of light freezing rain and freezing drizzle into the evening hours (instead of just after midnight) and am a little concerned that may not be fast enough. Don`t want to lock the midnight shift into something this early though, and will allow them some wiggle room. All indications remain that any potential freezing precip will be light and still do not anticipate much impact. This will need to be monitored however. && .PREV DISCUSSION... /issued 529 PM CST Mon Feb 5 2018/ AVIATION... /00Z TAFS/ Widespread fog and low clouds will affect all terminals throughout much of the day tomorrow. Fog will develop across KJCT and KSOA between 08-12z. Prior to the onset of fog, low stratus will bring MVFR conditions to the terminals. Once the fog develops, IFR conditions can be expected with visibilities dropping below 1/2SM. The low clouds and fog will spread north and reach KSJT by 09z. Fog will develop across the KSJT terminal bringing IFR conditions with 1/2SM visibilities and low ceilings. The fog will slowly begin to dissipate across the terminals between 16-18z, but low clouds will persist and MVFR with periods of IFR ceilings will continue across these terminals. At KABI, fog is not anticipated at this time and the mention of fog as been left out of this TAF package. The low clouds will bring MVFR/IFR ceilings with light drizzle to the terminal beginning at 10z and lasting throughout the rest of the day. PREV DISCUSSION... /issued 305 PM CST Mon Feb 5 2018/ SHORT TERM... (Tonight and Tuesday) .Colder and rainy Tuesday... Stratus continued to dissipated from west to east this afternoon, with a nice jump in temperatures into the 60s in the Concho Valley. Temperatures were still cool in the 40s in the Big Country. A cold front was moving into the northern Texas Panhandle this afternoon. Temperatures were not cold with 60s just behind the front. However there was much colder air in the 20s and 30s northern Kansas. The cold front will be moving into the Big Country Tuesday morning, and midday in the Concho Valley, and afternoon along I-10. Went cooler with highs in the upper 30s to lower 40s in the Big Country tomorrow. Temperatures should stay steady or fall slowly after frontal passage. Added patchy drizzle in the Concho Valley and areas east and south tonight after midnight as a warm front temporarily moves north. There is a 20 to 40 percent chance of rain Tuesday as the cold front pushes the moist air associated with the warm front, back south. Rainfall amounts will be light, generally a few hundredths of an inch. LONG TERM... (Wednesday through Tuesday) Main concerns for this forecast period will be the chances for a a wintry mix along and north of Interstate 20 Wednesday morning. Temperatures in the upper 20s combined with a slight chance of precipitation may lead to some areas seeing some light freezing rain during the morning. Otherwise, much colder temperatures are expected for Wednesday afternoon before warming back into the 60s for Thursday and Friday. The next cold front may pass through sometime around Sunday dropping temperatures back into the upper 40s to mid 50s. The next chance for rain will be on Monday with the best chances appearing to be south of Interstate 20. && .PRELIMINARY POINT TEMPS/POPS... Abilene 34 38 29 47 / 10 30 30 5 San Angelo 42 48 34 49 / 10 20 20 10 Junction 45 58 36 46 / 10 30 30 30 Brownwood 41 45 33 47 / 20 40 40 10 Sweetwater 32 37 28 47 / 10 20 20 5 Ozona 45 58 37 51 / 10 20 20 20 && .SJT WATCHES/WARNINGS/ADVISORIES... None. && $$ 07