Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/06/20

National Weather Service Wakefield VA
909 PM EDT Tue May 5 2020 .SYNOPSIS... Low pressure developing over the Carolinas will track to the south of the local area overnight before pushing offshore by Wednesday morning. A trough of low pressure will swing across the area later Wednesday afternoon into Wednesday night. High pressure will build into and across the region during Thursday. Another cold front will cross the region on Friday and Friday night. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... As of 905 PM EDT Tuesday... Late evening surface analysis shows ~1006 mb sfc low pressure centered from WV to to the mountains of VA/NC. A secondary low is starting to develop in srn NC/nrn SC along a stalled frontal boundary. Aloft, a trough over the Great Lakes is slowly propagating east-southeastward toward the area. E-NE flow prevails across the area on the north side of the boundary with temperatures mainly in the 50s (dew points in the 40s-low 50s). It is mainly dry at this hour, with a just a few showers streaming across the area. Still expecting showers to increase in coverage and spread across the area from W-E overnight (mainly after midnight). Pcpn chances lower from W-E during the 09-12z timeframe (except in the NE third of the CWA). Mainly minor changes were made with the evening update, although near-term CAMs (namely the last couple HRRR runs) have backed off somewhat regarding the potential for tstms across srn portions of the area overnight. Not enough confidence to remove thunder from the forecast (am seeing isolated elevated tstm development across NW/north- central NC on the cool side of the front). As such, will maintain slight chc thunder across srn VA/NE NC. QPFs through 12z range from 0.15-0.50" (highest E/lowest W). Previous Discussion as of 300 PM EDT Tuesday: The first wave of light rain associated with weak isentropic lift/warm advection has generally moved offshore. More showery type precipitation mainly west of the area will spread east tonight as the upper trough moves east. More focused precipitation is expected this evening across southside VA and NE NC as the secondary surface low develops and moves offshore overnight. In fact, could not rule out a thunderstorm across the far southern tier this evening into the early morning hours due to the very steep lapse rates aloft and MUCAPE values of nearly 1000 J/KG. As such, have maintained the slight chance of thunder mainly along/south of US 460 tonight. With the steep lapse rates and subsequent CAPE profile as well as the 40- 50kt of deep shear, one could not completely rule out hail if there is any storm organization tonight however this would likely occur south of the area in SPCs marginal/slight risk area co-located closer to the surface boundary. Showers will also spread across the rest of the area once again tonight simply due to the upper trough approaching and subsequent height falls, especially as the surface ridge centered just offshore moves northeast. Will therefore maintain likely or categorical pops for the rest of the area overnight. Lows will drop into the mid 40s NW and MD eastern shore to low-mid 50s SE. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/... As of 300 PM EDT Tuesday... Unsettled weather continues on Wednesday with the upper trough moving overhead and the surface low just offshore. Although the morning may be relatively dry as a weak dry slot moves across the area, will see increasing shower coverage especially across the north during the afternoon as the cold pool aloft (500mb temps around -22c) moves overhead and we some some diurnal heating. In fact, it would not be completely surprising to hear of small hail/graupel with any shower activity Wed afternoon. Will therefore maintain likely PoPs across the north Wed, with chance PoPs to the south where there will be less influence from the upper trough. Highs will be unseasonably cool again, with temps in the upper 50s north and mid-upper 60s south with a little more sunshine. High pressure finally builds in eventually by Thursday morning, although there continues to be chances for showers especially Wednesday before the upper trough axis moves offshore. Thursday will be Mostly Sunny though as the surface ridge builds in from the west and W-NW flow develops. Lows Wed night in the 40s (with upper 30s NW of RIC). Highs Thursday in the 60s. && .LONG TERM /FRIDAY THROUGH TUESDAY/... As of 300 PM EDT Tuesday... The cool pattern will continue into early next week at least. After a quiet Thursday, another cold front and upper trough will approach the east coast Friday. This will bring another round of light rain to the area especially Friday afternoon/night as a weak low moves up the Appalachians along the front. Behind this front, unseasonably cool conditions will move into the area with GFS 500mb height anomalies 2-3 standard deviations below normal across the Middle Atlantic. This will yield highs only in the 50s on Saturday but rebounding into the low-mid 60s on Sunday. Increasing chances for a frost or even a freeze Sun morning especially west of I-95 but even as far east as the interior coastal plain. In fact, the NBM V4.0 10th percentile min temps Sunday morning are in the upper 20s/lower 30s across much of the area away from the coast so this will need to be watched very closely in the coming days. Heights remain below normal through mid week. Could not rule out a stray shower on Monday with another weak frontal passage but for now will keep dry or just slight chance of showers. Temps for Monday/Tuesday will stay in the 60s with lows in the 40s. && .AVIATION /01Z WEDNESDAY THROUGH SUNDAY/... As of 755 PM EDT Tuesday... High pressure is centered a couple hundred miles off the nrn Mid-Atlantic coast as of 23z and is ridging southwestward into SE VA/NE NC. Meanwhile, weak low pressure is centered over the mountains of WV/VA. A secondary low is developing over srn NC/nrn SC. Dry conditions prevail at the terminals at this hour, with scattered light-moderate SHRAs approaching SBY from the W. As the secondary low tracks ENE through NC/moves closer to the area tonight, showers will develop and overspread the terminals from 02-05z and persist through much of the night. Pcpn is expected to end from W to E during the 08-11z timeframe. CIGS are still VFR/high-end MVFR at the terminals this evening, but are expected to lower to MVFR before dropping to IFR from SW to NE early Wed AM (mainly after 06z). Cannot rule out a rumble of thunder at ORF/ECG overnight but confidence in this is low. Latest guidance has actually backed off a bit with respect to thunder potential. CIGS rise to MVFR/VFR at the VA/NC terminals by late morning-midday Wed as winds increase out of the NW and some low-level drying occurs. At SBY, IFR CIGs likely persist through much of the day as the low-level flow remains N-NE and showers continue. Expect re-development of scattered showers Wed aftn at the remaining terminals (best chc at RIC/PHF) as an upper trough and cold front push through the region. VFR conditions prevail at RIC Wed night but CIGS could remain MVFR near the coast as clouds/isolated-scattered showers persist. Dry and breezy conditions develop Thursday with a NW wind in the wake of the cold front. Another chc of showers arrives Friday aftn/evening with another cold front. Dry and breezy again Saturday with a NW wind in the wake of the second cold front. && .MARINE... As of 345 PM EDT Tuesday... Afternoon surface analysis shows low pressure over eastern TN/KY while weak surface high pressure near the local area slips offshore. Winds vary considerably across the waters this afternoon with generally light and variable winds across the northern half of the area with 10-15 knot onshore flow in place across the southern half. Waves are 1-2 ft with seas 2-4 ft offshore. Low pressure will develop across the Carolinas and translate eastward overnight tonight. Onshore flow increases 15-20 knots for the southern coastal waters with generally 10-15 knot easterly winds in the southern bay and lower James river tonight. Enhanced (but sub-SCA) onshore winds will spread northward across the coastal waters through sunrise as the low emerges into the Atlantic. This low will strengthen modestly tomorrow morning while taking a more NE track offshore. Winds turn to NW as the low pulls away from the coast and increase to 15-20 knots with gust ~25 knots Wednesday night into Thursday morning. Waves build to 2-3 ft while seas increase to 3-5 ft offshore late Wednesday and especially into Thursday with strong offshore flow. SCA headlines are probable for the waters tomorrow night into Thursday. Conditions improve on Thursday as high pressure builds in from the southwest. Another strong cold front approaches the region on Friday with increasing SW flow ahead of the boundary and strong NW winds and CAA forecast behind the front for the start of the weekend. && .TIDES/COASTAL FLOODING... Increasing tidal anomalies associated with onshore flow near the mouth of the bay combined with high astronomical tides will result in some nuisance tidal flooding across the northern bay tonight. Coastal Flood Statements are in effect after 10pm tonight for Bishop`s Head and Cambridge in Dorchester county, MD as well as for bayside portions of Westmoreland, Northumberland, and Lancaster counties, VA. Astronomical tides remain elevated for the next few cycles and further instances of tidal flooding are probable in the coming days with multiple areas of low pressure/fronts affecting the region. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...None. && $$ SYNOPSIS...MRD NEAR TERM...ERI/MRD SHORT TERM...MRD LONG TERM...MRD AVIATION...ERI/MRD MARINE...RHR TIDES/COASTAL FLOODING...
Area Forecast Discussion
National Weather Service Bismarck ND
1017 PM CDT Tue May 5 2020 .UPDATE... Issued at 1017 PM CDT Tue May 5 2020 A few isolated showers continue across northwest and north central North Dakota, ahead of a mid level impulse that can be seen on water vapor moving down from southeast Saskatchewan. Have extended the isolated shower mention for a few hours for those areas, otherwise the forecast remains on track. UPDATE Issued at 706 PM CDT Tue May 5 2020 There has been a general downward trend in shower and thunderstorm activity over the past hour so, and expect that this trend will continue through the evening. Two geographic areas where isolated thunderstorms will remain possible this evening are southwest and far north central North Dakota. && .SHORT TERM...(This afternoon through Wednesday) Issued at 240 PM CDT Tue May 5 2020 A weak upper level shortwave will rotate into western North Dakota late this afternoon and tonight. This wave will be the focus for widely scattered afternoon showers and isolated thunderstorms, mainly across the west and south central. 19z RAP Mesoanalysis shows a pocket of 500+ J/kg SBCAPE across much of the west and portions of the south central. Although shear is quite weak, expect some isolated claps of thunder under the heavier showers that do develop. In general, the heaviest precipitation amounts will be likely across the southwest and portions of the south central, maybe a tenth of an inch or two. Coverage of showers will diminish as the sun sets. Temperatures will dip into the 30s overnight, possibly into the low 30s across the west. An upper ridge builds from the west as it deamplifies and we get a slight warmup with highs in the 60s and mainly dry weather. .LONG TERM...(Wednesday night through Tuesday) Issued at 240 PM CDT Tue May 5 2020 The upper ridge breaks down on Thursday as a compact upper low swings down into South Dakota from southern Montana. Most of the lift will remain west and south of the state border but the far southwest may see couple tenths of an inch of rain. On Saturday, an Alberta Clipper will sweep down from southern Canada, which will bring much cooler temperatures and even a chance of some light snow showers. Lows will fall into the lower 30s for much of the weekend with highs generally in the 50s and 60s. Various other waves will continue to slide down the ridge in a northwest flow regime. This active period will provide various chances for isolated to scattered showers but much uncertainty remains with regards to timing across the range of solutions shown by the global models. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 706 PM CDT Tue May 5 2020 Scattered showers are expected to diminish this evening. Other than a possible brief period of MVFR ceilings at KJMS this evening, VFR conditions should prevail through the forecast period. Northerly winds will become light and variable overnight, and remain around 10 kts or less through Wednesday. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...Hollan SHORT TERM...ZH LONG TERM...ZH AVIATION...Hollan
National Weather Service Hastings NE
726 PM CDT Tue May 5 2020 .UPDATE... Issued at 721 PM CDT Tue May 5 2020 Last couple runs of the HRRR have been a bit colder, so overnight temperatures were nudged down 1-2 degrees using the 10th percentile of available model guidance. With dewpoints forecast to recover back into the mid 30s, there is not much concern that it will fall any lower than this forecast. Patchy frost was also added to northwestern portions of the area. But with some remaining cloud cover and steady north winds, there should not be enough frost to warrant an advisory. && .SHORT TERM...(This evening through Wednesday) Issued at 334 PM CDT Tue May 5 2020 A mid-level vorticity max will swing through this evening and early overnight to give us some low chances of precip, especially in our northwest half of the CWA. Hi-res ensembles indicate that our chances would top out at 30 to 40 POPs as our ambient environment is rather dry, and a bit of a v-shape to soundings through early evening. Wind gusts should subside with surface cooling except for where convection pops up, and dry air will help induce potentially very gusty winds. .LONG TERM...(Wednesday night through Tuesday) Issued at 334 PM CDT Tue May 5 2020 Pattern is setting up to be a persistent ridge in the western United States with general troughing in roughly the the eastern half to two thirds of the country. Generally speaking, instability will remain low in the long term, with a bit more elevated instability showing up for Thursday into Friday. The most significant wave is still forecast to come through Wednesday night into Thursday/Thursday evening. For frost, wind speeds look a bit more elevated for Saturday morning, and temps have been nudged up, so perhaps less likely now. Still a ways off, so we will have to see. Long term ensembles and operational runs keep us below normal temperatures well into mid-May. We will not be getting the brunt of cold air overall as this is focused farther east, but we will likely fall short of normal highs near 70 or lower 70s for awhile. Periodic perturbations and troughs will probably give us chances of rain here and there, but this pattern is not generally conducive to heavy rain or widespread severe events. Although temps may get into the mid to upper 30s for parts of the CWA 2 to 3 times during the long term, our best chance of frost may be Saturday morning when wind subsides more and rain chances are decreased. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Thursday) Issued at 622 PM CDT Tue May 5 2020 We still could see a few showers across central Nebraska this evening, but the threat for thunderstorms has decreased and no longer warrants inclusion in the TAFs. After this moves out of the area, skies will clear out tonight. We will have to watch for some low-midlevel clouds moving in from northeast Nebraska, but this should largely stay northeast of KGRI. Winds will also decrease tonight, and will be noticably lighter tomorrow with gusts only 15-20kts. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ UPDATE...Mangels SHORT TERM...Heinlein LONG TERM...Heinlein AVIATION...Mangels
Area Forecast Discussion
National Weather Service North Platte NE
746 PM CDT Tue May 5 2020 .SHORT TERM...(This evening through Wednesday night) Issued at 353 PM CDT Tue May 5 2020 The primary forecast challenges through the weekend are temperatures and precipitation. Strong northwest flow aloft will keep conditions rather cool and wet the next several days. This evening and tonight... Expanded PoP a little farther west to account for scattered showers and storms in the wake of a cold front and along a stout shortwave. Convective initiation is underway in SoDak as of 20z with the activity moving toward far north central Neb. Elsewhere, towering cu fields are evident over much of the forecast area and radar echoes are starting to light up in NW Neb (although it`s likely virga attm). RAP mesoanalysis indicates some instability, in the form of 500 j/kg MUCAPE and mid level lapse rates near 8C/km. Expect increased convection over the Sandhills through the evening. Coverage should remain scattered as the low levels are quite dry (dew point depressions 30+ F), and begin to taper after sunset. Surface high pressure settles into the Sandhills overnight, resulting in nearly calm winds and mostly clear skies. This will be another favorable setup for a cool night. Blended in some cooler guidance for lows ranging from around 30F in the panhandle to upper 30s north central. Included frost mention for areas west of Hwy 83. Wednesday and Wed night... Winds slowly transition to southerly and skies remain mostly clear through the day as the surface high slides southeast into the Missouri Valley. Negligible temperature advection occurs at H85 with a weak ridge axis bisecting the forecast area. Highs will generally be in the lower/mid 60s, similar to today. Later in the evening, upslope flow intensifies and weak moisture advection resumes. The next surface low and front emerge from the Rockies, helping to reinforce lift. A band (or two) of precip should develop ahead of the front where isentropic upglide really picks up. The 305K sfc is slated to span almost 200mb across the forecast area alone with 50kt winds converging to 20kt flow farther east. Despite the decent signal for precip, thunder parameters are pretty weak. Included likely PoP across the north and high end chc elsewhere. .LONG TERM...(Thursday through Tuesday) Issued at 353 PM CDT Tue May 5 2020 Thursday and beyond... The cool and wet pattern continues into next week, especially with a tandem of closed upper lows rounding the Eastern U.S. trough. The combination of strong forcing in the mid and upper levels as well as several surface front passages present multiple precip chances, notably Thursday, Saturday, and early Monday. May see some thunderstorms with the round on Saturday, mainly across north central Neb, where instability is greater. High temps are held to the 60s through the weekend, and may not leave the 50s on Monday. Nighttime lows will persistently be in the 30s, so will need to monitor the potential for frost. Conditions may be ripe for widespread freeze Sunday morning. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 744 PM CDT Tue May 5 2020 VFR conditions will prevail over the next 24 hours. Winds will diminish this evening out of northwest. Tomorrow afternoon winds will shift to the southeast across much of the forecast area and remain light around 5 to 10 kts. && .LBF WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...Snively LONG TERM...Snively AVIATION...Gomez
Updated for 00Z Aviation Forecast Discussion below.

PREV DISCUSSION... /issued 350 PM CDT Tue May 5 2020/ DISCUSSION... Drier air will settle over the Mid-South tonight in the wake of the cold front that moved through the area earlier today. There are still some light radar echoes along/south of the I-40 corridor, but much of this is not reaching the ground. Other than a few sprinkles this afternoon, we`re not anticipating much in the way of precip over the next 48 hours. Expect generally benign and cooler weather conditions across the region Wednesday. A weak wave moving across the Upper OH Valley will drive a reinforcing cold front into the area tomorrow. This will result in cloud cover across west TN into the Bootheel, but the relatively dry low-levels will preclude rain chances. Should a shower develop, we`re looking at very limited coverage. This wave will pass by midday with clearing skies in the afternoon and evening. Temperatures will top out in the 60s across most of the area tomorrow. Most of Thursday will be nice with highs approaching 70F. We do anticipate an increase in cloud cover throughout the day and this may lead to a few very light showers west of the MS River in the afternoon. Otherwise, dry weather is expected during the daytime hours. Rain chances will increase Thursday night as a compact shortwave trough traverses the Ozarks. Strong forcing for ascent will overspread the region working in conjunction with warm-sector warm advection to produce scattered showers and a few thunderstorms. Instability doesn`t look too impressive (and is mainly elevated at that), limiting the severe weather potential. We`ll continue to monitor how this system evolves over the next few days. Cooler and drier air will return over the weekend. Temperatures Saturday will be on the cool side for May standards with highs in the low/mid 60s. The well below normal temperatures will persist Saturday night as temperatures cool into the low/mid 40s. A few areas in the TN Valley could briefly dip into the upper 30s early Sunday morning. The good news is that we don`t anticipate any rainfall across the Mid-South Saturday through Monday. The flow aloft becomes a bit more zonal by Tuesday with southern stream shortwave energy approaching from the west. This will result in a return of low rain chances to the region through midweek. MJ && .AVIATION... 00Z TAFs Following VFR conditions overnight, NW winds will become gusty following a reinforcing cold frontal passage. HRRR hints at some briefly stronger gusts over 30KT, mainly west of MEM over the eastern AR delta. These higher gusts should be brief. VFR stratocumulus deck should clear as winds become light in time for the Wednesday evening MEM inbounds. PWB && .MEG WATCHES/WARNINGS/ADVISORIES... AR...None. MO...None. MS...None. TN...None. && $$
Area Forecast Discussion...Updated
National Weather Service Portland OR
820 PM PDT Tue May 5 2020 Updated aviation discussion .SYNOPSIS....Showers and slight chance of thunderstorms possible this evening. A frontal system will push across the area tonight into Wednesday morning. A switch to drier and much warmer weather begins late Wednesday as high pressure builds over the region and will persist through the weekend. && .SHORT TERM...Tonight through Saturday...Current GOES satellite imagery and radar reflectivity indicate isolated to scattered shower activity occurring along the northern Coast Range and Cascades. Slight chance of thunderstorms will also be possible with a few of these showers as instability continues to increase late this afternoon to early evening. The highest potential of thunderstorms will be mainly confined to the higher elevations east of PDX along the north OR/south WA Cascades. Brief periods of heavy rain and small hail are possible within a few of these convective showers. Showers should taper off a little bit around sunset. Elsewhere expect mainly sunny and dry conditions through the Willamette valley this evening with temperatures reaching the low to mid 70s while the coastal areas remain around 60. Satellite imagery Tuesday afternoon also shows an approaching elongated front associated with a low southwest of Haida Gwaii. Strong southwesterly jet aloft will help push upper level trough across western OR and WA rather quickly late tonight through Wednesday morning. Gusty southerly winds are likely ahead of the front as high pressure continues to build along the southern OR coast this evening. Frontal system will push across the coast between 6Z to 9Z with a westerly wind shift behind. Upper level support will likely enhance precipitation rates along the coast with rainfall totals of up to a quarter of an inch. RAP analysis does indicate some weak instability along the front which could produce a few isolated lightning strikes along the coast around midnight. Expect the front to push through the area by early Wednesday morning. Rain accumulations along the Cascade range up to 0.20 inches and around 0.10 inches with the Willamette Valley. The remainder of Wednesday will see slightly cooler temperatures with showers dissipating as an upper level ridge builds across the NE Pacific and surface high pressure moves north just off shore towards Vancouver Island. The upper ridge shifts over the entire Pacific Northwest region Thursday and will be the dominate synoptic feature through most of the weekend. A thermally induced trough will develop from northern CA into southern WA turning winds offshore and maintaining dry conditions. Temperatures will begin a warming trend Thursday through the weekend, with the valley temperatures expected to reach into the mid 80s possibly by Saturday. Temperatures along the coast will likely warm into the low to mid 70s as well. /DDH .LONG TERM...Saturday night through Wednesday...Upper level ridging will continue Saturday night into Sunday allowing the thermally induced trough to persist. This dry, warm and offshore flow regime will persist through Sunday with temperatures only a few degrees cooler than Saturday. Ensembles and deterministic model guidance shows the ridge shifting eastward as an upper level low moves into the NE Pacific west of OR late Sunday. This will allow a strong surface low to move into the area by Monday. This low will turn winds back onshore along with precipitation chances increasing early next week. /DDH && .AVIATION...A few showers continue to move north over the Cascades this evening, but should decrease a little shortly after sunset. Otherwise, conditions across the interior remain VFR through tonight with increasing mid and high clouds. The coast will see MVFR cigs solidify over the next several hours as onshore flow increases. An incoming quick moving front will bring the return of light rain to the coast by midnight tonight, with rain spreading inland overnight. As rain moves across the forecast area expect a few hours of local MVFR cigs along with some gusty southerly winds to 20 kt. Conditions will become showery behind the front, with a mix of MVFR and VFR showers through the morning hours. Expect shower activity to slowly decrease during the afternoon as high pressure starts to build into the Pac NW. PDX AND APPROACHES...Conditions remain VFR through tonight with increasing mid clouds. A quick moving cold front will bring a few hours of light rain along with some MVFR cigs between 09Z and 12Z. Mainly VFR showers continue through the morning hours, then slowly decrease during the afternoon. A few hours of gusty southerly winds to 20 kt possible as the front moves across the terminal late tonight/early tomorrow morning. /64 && .MARINE...Seas are slowly subsiding from their earlier peak and will let the SCA expire at 3 PM as planned. A fast moving cold front will cross the waters later this evening. There will be a very brief period where winds will gust 20-25 kt as the front moves from West to East, but given the very short duration of 1 hour or less, do not feel a SCA is warranted. Will highlight the brief increase in the CWF, however. Seas are expected to remain around 9 ft, but again could very briefly bump back up to 10 ft as the front crosses. Thereafter, high pressure builds along the west coast with a surface thermal low building north from California. Expect northerly to northeasterly flow over the waters to develop Wednesday afternoon, possibly reaching SCA gusts 20-25 kt Wednesday evening, but more likely on Thursday. Will then see little change heading in to the weekend when the ridge starts getting nudged eastward beginning Saturday. Sunday looks to bring a southerly wind reversal. Westerly swell will continue to subside through the remainder of the week as northerly wind waves begin to dominate. Expect COmbined seas to largely be 5-7 feet. /JBonk && .PQR WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. PZ...Small Craft Advisory until 3 PM PDT this afternoon for coastal waters from Cape Shoalwater WA to Florence OR out 60 NM. Small Craft Advisory until 7 PM PDT this evening for Columbia River Bar. Small Craft Advisory from 3 AM to 8 AM PDT Wednesday for Columbia River Bar. && $$ Interact with us via social media: This discussion is for Northwest oregon and Southwest Washington from the Cascade crest to 60 nm offshore. This area is commonly referred to as the forecast area.
National Weather Service Raleigh NC
1000 PM EDT Tue May 5 2020 .SYNOPSIS... A cold front will push east through the area early Wednesday morning followed by a secondary cold frontal passage will Wednesday afternoon. Chilly high pressure will build into the area late week. && .NEAR TERM /THROUGH TONIGHT/... As of 955 PM Tuesday... We have cancelled severe thunderstorm watch 168 given a lack of substantial destablization north into the Piedmont and coastal plain. Deep convection has been confined mainly to the warm front just south of the NC/SC border, tracking west to east and likely hindering better southerly return flow north into the wedge airmass analyzed in the central Piedmont, where models had indicated potential for elevated convection owing to steep mid-level lapse rates on the north periphery of a EML over the SE US. The storms continue to move off to the ESE and pose no additional threat to the southern Piedmont/coastal plain. Meanwhile, scattered convection has been moving through the Blue Ridge from the instability axis west of the mountains and just ahead of the cold front analyzed over eastern TN. These elevated storms have actually held together as they track through the northern Piedmont, with an uptick in lightning strikes since 9pm, but should remain sub-severe given that they are out of ahead of better large scale forcing and not likely to be organized enough to produce large hail. Latest HRRR suggests they will track off to the ENE out of the CWA by 05Z. A few scatted showers may linger through 09Z before the front pushes through the area. Lows 51-61 NW to SE. && .SHORT TERM /WEDNESDAY AND WEDNESDAY NIGHT/... As of 230 PM Tuesday... The surface low will lift northeast away from NC toward New England while the trailing cold front surges eastward off the coast. Cool, dry air will advect into the area in the wake of the front, though the better push of cold air will occur Wednesday night. An upper level shortwave will swing through the region Wednesday afternoon, which could provide enough forcing for showers to develop. The big question is if showers develop, where will they and what will the coverage be. High-res models suggest scattered showers across central NC between noon and sunset, thus will introduce a slight chance for showers during the aft/eve. Highs will likely top out in the mid 60s NW to mid 70s SE. Lows will bottom out in the low to mid 40s, though a few of the usual cooler spots could dip into the upper 30s. && .LONG TERM /THURSDAY THROUGH TUESDAY/... As of 300 PM Tuesday... Thursday and Thursday night will largely be dry in the wake of the departing upper wave and the next one approaching. Surface high pressure will build east through the Deep South and off the Southeast US coast by Friday morning. Highs will likely top out in the mid to upper 60s with lows again bottoming out in the 40s. Friday and Friday night: A deepening upper low will slip southeast through Canada into the Great Lakes Thursday and Friday before progressing east through the Great Lakes and into the Northeast Friday night through Saturday. A shortwave disturbance swinging around the base of the trough the Plains and MS Valley will move through the mid-Atlantic late Friday into Saturday. At the surface, a low will develop off the southern Rockies Thursday night and move through the Midwest and into the TN Valley by Friday afternoon. Latest model solutions indicate the low strengthening as it lifts northeast along the Appalachians toward the Northeast US Friday eve/night. There is still a descent chance for some showers and storms Friday aft/eve, however there is still some uncertainty regarding the coverage and strength. Largely expect any showers to move out of the area overnight as cold, Canadian high pressure builds into the area. Temperatures are also still somewhat uncertain, with highs ranging from mid 60s to mid 70s and lows generally in the 40s. Saturday through Tuesday: Cool high pressure will build eastward into, over and through the mid-Atlantic over the weekend while generally westerly flow persists aloft. Expect cool, dry weather Saturday and Sunday, with below normal temperatures. A shortwave aloft will swing through the Great Lakes, OH Valley and Northeast US early next week, but for now do not expect any significant weather impacts across central NC as a result. Dry weather should dominate through Tuesday and while some moderation is expected, temperatures should remain below normal for the duration. && .AVIATION /00Z WEDNESDAY THROUGH SUNDAY/... As of 745 PM Tuesday... MVFR ceilings linger around GSO/INT, while strong storms are tracking west to east along the NC/SC border. Expect the bulk of the storms to remain near the SC border, likely impacting FAY by 03Z, with decreasing chances of storms near GSO/INT/RDU/ since the previous TAF issuance. An isolated shower is still possible at those sites, and some forecast guidance suggests storms may congeal and track far enough north to impact RWI by 04Z...though confidence in this is low. Most MVFR ceilings are expected in showers and storms, with a period of IFR indicated between 06-10Z at all sites before a cold front sweeps across the area. VFR conditions are expected on Wednesday with NW winds that will gust to 20-25kt during the afternoon Outlook: VFR conditions will continue through Friday. A cold front moving east through the area will bring the next chance of rain and sub-VFR flight restrictions late Friday and Friday night. VFR conditions will return by early Saturday && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...BLS NEAR TERM...BLS SHORT TERM...KC LONG TERM...KC AVIATION...CBL/BLS
Area Forecast Discussion
National Weather Service Blacksburg VA
958 PM EDT Tue May 5 2020 .SYNOPSIS... A warm front across northeastern Tennessee and draped down through South Carolina will shift slightly northward bringing some unstable air into far southwest Virginia tonight. A low pressure center will move east across northern Virginia by Wednesday morning and drag a cold front through the Appalachian region by the morning and then off the coast by Wednesday evening. High pressure then builds in Thursday, before another front arrives Friday. && .NEAR TERM /THROUGH WEDNESDAY/... As of 957 PM EDT Tuesday... Made some additional adjustments to temperatures tonight capturing the cooler air sinking southward. Modified pops for tonight into Wednesday morning, slowed the exit of the convection late tonight into Wednesday morning. Extended the duration of the thunderstorms across the south a few hours. The threat for stronger convection will remain to our south tonight. Low temperatures tonight will vary from the lower 30s in the northwest mountains to around 50 degrees. As of 758 PM EDT Tuesday... Made some minor adjustments in temperatures and dew points for this evening into Wednesday morning utilizing the latest surface obs, their trends and blended in the NBM. In general, held up this evening temperatures in the west before allowing the drop overnight into Wednesday morning. Scattered showers and thunderstorms are forming in the unstable air to our west and translating into western portions of the forecast area. SPC Mesoscale analysis showed surface based cape of 500 to 1000 j/kg pushing into far southwest virginia and eastern Tennessee. Latest region radar images showed scattered showers and isolated thunderstorms from southern West Virginia southward to Western North Carolina. Decided to expand the isolated thunderstorms into western areas of the forecast area tonight, basically around I77 corridor. Shaped pops and weather towards a blend of the HRRR and nam for this evening into tonight. more changes later... As of 225 PM EDT Tuesday... Mid afternoon radar and observations show area of rain has moved east of the RNK county warning area with some scattered showers reforming in the mountains, but any thunder with these will be from elevated instability as surface wedge remains firmly in place and temperatures in the lower 50s and even some upper 40s. However, warm frontal boundary in NE Tennessee is still expected to move north late this afternoon into the evening and may still sneak into our far SW Virginia counties as well as NW NC, to allow some surface-based instability and a few more storms to develop. With plenty of wind shear to work with and storms forming near the boundary, still cannot rule out a severe threat, with an isolated tornado possible. Thinking now that if these do get into our area it will be limited to southwest of a line from Bluefield to Wytheville down to Wilkesboro, but may even more limited to areas like Richlands to Marion to Boone. Any severe threat will likely be also be limited in time to very late afternoon and into early evening. A few thunderstorms will likely shift up into the more stable air before weakening but would not pose any severe weather threat. Farther east, the warm front will remain well south of the RNK county warning area but a few storms could sneak up to near the Virginia border this evening before moving east by midnight. Any scattered stronger storms with high rainfall rates could pose a localized flash flood threat if they move over the same areas that picked up 0.50-1.00 inches of rain earlier today, mainly southwest of a line from Bluefield to Hillsville. Threat not widespread or significant enough for flash flood watch though. Otherwise for tonight, showers and lingering storms move east after midnight with some remaining upslope showers in the far west late tonight behind surface cold front as winds shift to the west and northwest. Wednesday behind the front and upper trough with cool air aloft, some isolated showers may once again form during the afternoon, with latest hi res guidance suggestion that associated weak upper wave may favor an area of showers across the southern third of the forecast area, with only very limited thunder threat given very marginal mid-level instability. Although at least a slight chance of a few showers really anywhere by afternoon, and still some lingering lighter showers with the upslope flow on far western slopes. Did not include any mention of thunder for any shallow convection on Wednesday. Another cool day with wide temperature ranges of lower to mid 40s far west and lower to mid 60s far east with more sun, but not sure how long sun will last as cumulus field may fill back in quickly by afternoon. && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/... As of 100 PM EDT Tuesday... A broad upper level trough will cross over the Mid Atlantic during Wednesday night. Lingering upslope moisture should eventually come to an end overnight as drier air arrives. Colder air should allow temperatures to come close to the freezing mark by Thursday morning, but mixing from the northwest breeze will likely inhibit any frost development. High pressure will bring lighter winds and dry weather on Thursday before departing offshore by Thursday night. Meanwhile, a low pressure system will form over the Plains and push a cold front toward the Ohio River Valley. By Friday morning, the cold front should reach the Appalachian Mountains. Rain chances have been increased for Friday due to the higher confidence portrayed in the model solutions regarding the widespread coverage of moisture. This cold front should exit on Friday night, but winds will pick up from the northwest as cold air advection increases. Lingering upslope rain showers could change to snow showers or flurries overnight across the higher elevations from Boone to Lewisburg. However, any snowfall accumulations appear to be light. Freeze headlines are also becoming increasingly likely for Friday night along and west of the Blue Ridge. && .LONG TERM /SATURDAY THROUGH TUESDAY/... As of 100 PM EDT Tuesday... After a cold start to Saturday, temperatures will continue to run well below normal for early May due to persistent troughing across the eastern United States. Winds may become more gusty during the day as boundary layer mixing taps into the higher momentum air aloft, so speeds have been adjusted upward to indicate an increase in confidence for the potential of 30-40 MPH gusts along the Blue Ridge. High pressure should settle over the Mid Atlantic by Saturday night and bring dry weather through Sunday. A weak low pressure system will emerge from the Great Lakes on Sunday night, and it should bring the next chance of rain mainly west of the Blue Ridge by early Monday morning. Lingering showers could persist into Monday afternoon before another area of high pressure clears out the moisture by Monday night. Tuesday appears generally dry according to the GFS with high pressure under control as the flow aloft becomes more zonal, but the ECMWF shows another frontal boundary arriving from the west that could introduce a slight chance of rain west of the Blue Ridge by Tuesday afternoon. && .AVIATION /02Z WEDNESDAY THROUGH SUNDAY/... As of 736 PM EDT Tuesday... SCT to BKN MVFR clouds will transition to MVFR/IFR ceilings tonight in areas of convection, low clouds and fog. A few thunderstorms are possible for the next couple of hours from far Southwest Virginia, across the Northwest North Carolina mountains, and into the Piedmont of North Carolina. Development of storms to the west of KBLF, may move across the KBLF taf site. Kept the mention of thunder at KDAN as scattered storms are forming in Northwest North carolina this evening. East to southeast winds will relax this evening and then shift to West to Northwest and pickup Wednesday morning and gust from 15-20 kts on Wednesday as MVFR and IFR conditions do not lift until later Wednesday morning. May remain MVFR at KBLF and KLWB much of the day due to the Northwest upslope flow and some continuing scattered showers, but may lift and break out at KBCB and portions of the New River Valley eventually. Medium confidence on ceilings,visibilities and winds during the taf period. Extended Aviation Discussion... High pressure arrives by Wed night-Thu to allow VFR to return to even the western TAF sites, before a front moves in with more shower chances Friday though mostly expecting VFR with some MVFR in the mountains. Drier weather is expected Saturday with gusty NW winds. Scattered MVFR showers may be possible in the northwest mountains on Sunday. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...SK NEAR TERM...KK/SK SHORT TERM...PW LONG TERM...PW AVIATION...KK/SK