Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/01/19

Area Forecast Discussion
National Weather Service Columbia SC
920 PM EDT Sun Mar 31 2019 .SYNOPSIS... Cooler than normal temperatures are expected this week with a coastal low pressure system Tuesday. Warmer and drier conditions will occur midweek. Another cold front will approach the region later in the week with a chance of showers. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... The cold front has moved offshore and showers remain south of the area. There is cold air advection behind the front, and temperatures will continue to fall through the night, with lows in the mid 30s to lower 40s. Dry air is overspreading the area, and precipitable water values will also continue to decrease. However, a southwest flow aloft will hold high level clouds over the region. Winds should stay up through the night so temperatures will remain above freezing and fog is not expected. && .SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY/... The next system that will be affecting the region for Monday night into Tuesday continues to indicate rainfall, especially across the eastern portion of the CWA. Model trends have been very consistent over the past few days with the NAM being the most aggressive and closest to the coast as the system develops over the northeast Gulf of Mexico. The ECMWF is in the middle and the GFS continues to keep the bulk of the moisture and system offshore. Given the consistencies between the models have continued with the compromise ECMWF. Monday looks to be an unseasonably chilly day with some high clouds across the region with temperatures in the middle 50s north to lower 60s south. The clouds will thicken as the moisture deepens Monday night into early Tuesday as the system becomes better organized along the southeast coast. Isentropic lift will increase across the area late Monday night into early Tuesday. This will likely be the best window for rainfall across the Midlands and CSRA. Expect the heaviest amount of rain to be across the southern CSRA and eastern Midlands along and east of the I-95 corridor. Have increased pops in that region for the period as pops will range from the high chance across the Piedmont to categorical along the I-95 corridor. Rainfall amounts will also be less west to greatest east. There looks to be a tight precipitation gradient and areas to the west may see less than one quarter inch to near an inch closer to the coast. Temperatures will be chilly on Tuesday with rainfall and chilly northeast to north low level winds. Highs will only be in the 50s across the Midlands and CSRA. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... Expect deeper moisture to push out of the area Tuesday night with high pressure and warmer/dry conditions returning for Wednesday and Thursday. Another front with deep moisture flux ahead of it from the Gulf coast region into the Southeast States by Friday will result in another chance showers but near or above normal temperatures. This system will push across the area by Friday night and weak high pressure will build in for the weekend. Expect temperatures to remain at/above normal for much of the period. && .AVIATION /01Z MONDAY THROUGH FRIDAY/... Expect VFR conditions through the 24-hour TAF period. The dry air mass behind the cold front will dominate during the period. Satellite trends support continued upper cloudiness. The GFS and NAM Bufkit momentum transfer tool plus HRRR suggests a surge in the cold air advection overnight with gusty winds. The GFS and NAM Bufkit momentum transfer tools indicates continued gusty winds during much of the day Monday. Expect gusts around 16 knots. EXTENDED AVIATION OUTLOOK...Restrictions possible Monday night through Tuesday as a low pressure system moves through the region. && .CAE WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. && $$
National Weather Service Jackson KY
1054 PM EDT Sun Mar 31 2019 .UPDATE... Issued at 1054 PM EDT SUN MAR 31 2019 Based on recent trends in observations and some guidance and a look at Model Certainty, confidence in ridgetops and more open terrain locations falling a degree or two lower tonight has increased. Slight adjustments down for min T in those locations have been made. The record low at JKL of 24 from 1987 could be approached. The record low at LOZ of 22 from 1994 appear much less likely to approached. UPDATE Issued at 800 PM EDT SUN MAR 31 2019 High pressure continues to build into the region with cumulus and stratocumulus continuing to mix out. Dewpoints are currently in the teens to lower 20s across the region. The pressure gradient will continue to slacken as the night progresses. Low temperatures as low as the upper teens in the coldest locations still look on target for the most part with some ridge/valley differences due to expected earlier decoupling in the valleys. Some recent guidance does suggest that temperatures on ridgetops and more open terrain locations could fall a bit more than the current forecast and this potential will continue to be monitored. At this time, only minor adjustments were made to hourly temperatures based on recent trends in observations. && .SHORT TERM...(This evening through Monday night) Issued at 450 PM EDT SUN MAR 31 2019 20z sfc analysis shows high pressure building effectively into eastern Kentucky. This has ended the last of the light showers in the far east and also dissipated most of the post frontal clouds - though some cu has developed in the colder air for western parts of the CWA. The winds are still blowing pretty good from the northwest at 10 to 15 mph with higher gusts - adding to the chill. Temperatures only managed to climb back to the upper 30s northwest and mid 40s south. Dewpoints, meanwhile, continue to fall as drier air is advected into the area with upper teens seen northwest and lower 20s southeast. The models are in decent agreement aloft through the short term portion of the forecast. They all depict the southern node of the deep North American trough pulling northeast out of the area into Monday morning. Heights will start to rebound into the day ahead of a southern stream trough moving through the Southern Plains that evening. The NAM is weaker with this wave than the GFS and ECMWF, but still pretty close. The energy with this will spread into Kentucky Monday night favoring its southern extent - but with still some significance closer to Kentucky. Given the general agreement and low spread through the period will favor a model blend with a lean toward the HRRR for near term details and NAM12 thereafter. Sensible weather will feature a very cold start to April as clear skies and lightening winds set up a good night for radiational cooling. With this, already cool temperatures will fall quickly this evening as a hard freeze ensues for the entire area overnight. Locations where the growing season has begun are under a freeze warning from late this evening into Monday morning. Widespread frost can also be expected, though the ridges may be too dry for much to develop. The deeper valleys will also be colder than the thermal belts and ridges tonight. Sunny skies Monday morning will help temperatures to rebound with just some high clouds possible moving in from the west late in the day. These clouds will likely thicken and lower Monday night and a stray shower cannot be ruled out depending on how a passing southern stream wave develops. For now, have kept it dry but with some single digit PoPs into early Tuesday morning in the far southeast. Again the CONSShort and ShortBlend guidance where used as the starting point for the grids with some significant adjustments to low temperatures tonight and to a lesser extent Monday night to account for generally favorable radiational cooling conditions leading to small to moderate ridge to valley temperature splits both nights. As for PoPs, the only adjustments were to keep them sub 15 percent Monday night into Tuesday morning due to uncertainty with the northern extent of the southern wave at the end of the period. .LONG TERM...(Tuesday through Sunday) Issued at 330 PM EDT SUN MAR 31 2019 The extended will start off slightly cooler than normal, with highs in the upper 50s expected for Tuesday. After that, we can expect several days of above normal temperatures across the area. A ridge of high pressure will become firmly entrenched across the region through Thursday afternoon. Daily highs from Wednesday onward will vary from the upper 60s to the low to mid 70s. Nightly lows will be in the 40s and 50s most of the period. The exception to this will Tuesday morning, when we are expecting to see lows ranging from the upper 20s to mid 30s. Some valley locations may experience frost early Tuesday morning. We may also frost across the area Tuesday night into early Wednesday morning, as temperatures fall into the upper 30s across the area. The latest model data is suggesting that the next chance for rain across the area will be from late Thursday through Friday night. The model blend seemed a bit too fast with the precipitation onset on Thursday, so the precip probabilities that day were modified accordingly base on the more reasonable timing seen in the ECMWF and GFS models. A few thunderstorms will be possible Thursday night and Friday, as a trough of low pressure moves across the Ohio Valley. Once this precip exits the area Friday night, we should see dry weather going into the weekend. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) ISSUED AT 808 PM EDT SUN MAR 31 2019 High pressure continues to build into the region with the pressure gradient gradually slackening. Winds at the TAF sites will initially be in the 5 to 10KT range, but should become closer to 5KT by 6Z as the center of the high nears the area. With the high building in and drier air working in as well, cumulus and stratocumulus have dissipated giving way to VFR. High pressure will dominate through the end of the period with VFR persisting. && .JKL WATCHES/WARNINGS/ADVISORIES... Freeze Warning until 10 AM EDT Monday for KYZ058>060-068-069-079- 080-083>088-104-106>120. && $$ UPDATE...JP SHORT TERM...GREIF LONG TERM...AR AVIATION...JP
Area Forecast Discussion
National Weather Service Lubbock TX
846 PM CDT Sun Mar 31 2019 .UPDATE... Minor update to boost PoPs into the 15-25% range over much of the Caprock after midnight tonight. Water vapor imagery shows the upper low that was anchored near the Four Corners most of today was now accelerating southeastward as expected. The low will weaken/open as is emerges over the southern High Plains late tonight. Ahead of the low, increasing lift has been producing precipitation aloft from central New Mexico into the western Texas Panhandle and northwestern South Plains much of this evening. Light rain and light snow were being reported from Dalhart and Clayton westward into north-central New Mexico. However, a relatively deep dry sub-cloud layer has kept the moisture from reaching the ground in our CWA to this point. Eventually, the persistent moistening from aloft should be sufficient for a few areas of sprinkles/flurries to surface, and recent runs of the HRRR and RAP even suggest one or two narrow swaths of light snow could grace the southwest Texas Panhandle and/or the western to central South Plains after midnight. Any snow should be spotty and light, but a few locations could see a quick dusting of snow accumulate in grassy locations in the pre-dawn hours of Monday. Given this, we have decided to increase PoPs to add a low mention of light snow over much of the Caprock in the 06-12Z time-frame. Given the marginal temperatures and light snow totals (if any), impacts should be minimal. Aside from the adjustments to the PoP/Wx/Snow grids, no other changes were made to the ongoing forecast. && .PREV DISCUSSION... /issued 626 PM CDT Sun Mar 31 2019/ AVIATION... VFR conditions will prevail through the next 24 hours. PREV DISCUSSION... /issued 300 PM CDT Sun Mar 31 2019/ DISCUSSION... A nearly stationary and compact upper low centered almost directly atop the Four Corners was finally getting a kick southeastward this afternoon courtesy a 200 mb jet streak spreading across the Great Basin. Streaks of mostly opaque cirrus with virga already over our region should continue to expand tonight ahead of this wave as large scale ascent improves in response to favorable upper divergence ahead of the low. Although some cumulus are noted on satellite and area skycams across our far NW counties, moisture deficits are pretty sizable from about 6000 feet up to 10k feet. Additional virga /top-down moistening should erode a chunk of this layer and culminate with some sprinkles and eventually flurries once wet bulb cooling deepens. Using primarily the HREF, this process should initially occur across our N-NW zones this evening before redeveloping farther S-SW after midnight with the arrival of a 500 mb jet streak and deeper saturation. However, this second batch of ascent will still have to overcome the aforementioned moisture deficits that were left largely untouched compared to areas farther north that will see a bigger window for top-down moistening. As such, most model soundings over the southern half of the CWA show sprinkles and flurries after midnight. A steady decay of the upper low during most of this time doesn`t bode well for much in the way of measurable precip, so PoPs were pulled below 15% for now. Following the decaying low, clouds should clear from W-E with little hesitation on Monday morning as heights aloft rebound swiftly. Downslope winds meanwhile should ensure highs reach into the 60s for a change, before zonal flow aloft amplifies on Tue and Wed spurring breezy and windy conditions, respectively. High temps from Mon-Wed should easily surpass the unusually cool Superblend and Nationalblend numbers given dry boundary layer conditions and favorable downslope winds. SW winds on Wed are still favored in the 25-35 mph range given the base of a shortwave trough arriving around peak heating. Following the buildup of modified moisture return from the Gulf on Wed, a decent dryline looks to develop just east of the CWA by Wed afternoon. Combined with the aforementioned upper trough, some dryline storms should ignite just east of our CWA. Unfortunately, a more westerly dryline position does not appear to be in the cards with this setup given only modest and shallow moisture return - conditions easily overwhelmed by very dry and gusty SW winds. A cold front on the heels of Wednesday`s trough still looks to fall well short of the Gulf which should allow a healthier return of low level moisture by later in the week. Precip chances still appear reasonable late Fri into the weekend provided a low latitude and slow moving trough overspreads much of West Texas. Not yet believing the GFS` depiction of this wave cutting off nearby, so for now we are siding with a more progressive trough per the GEFS mean, ECMWF and CMC. && .LUB WATCHES/WARNINGS/ADVISORIES... None. && $$ 23/51/93