Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/21/17

Area Forecast Discussion...Updated
National Weather Service Billings MT
821 PM MDT Mon Mar 20 2017 .UPDATE... Widespread precipitation across the CWA this evening as Pacific moisture interacts with short wave energy in westerly flow aloft. Bumped up PoP`s for rest of evening in many locations. Precipitation is mainly light, but there is indication of some pockets that look a little heavier. Rather warm yet in SE corner of state where winter weather advisory is in play until 18z tomorrow. Will need some dynamic cooling to help change phase to snow later tonight, but models still suggesting this will happen so will let the advisory ride for now. Still, expect any impacts to be limited. BT && .SHORT TERM...valid for Tue and Wed... Radar shows shower activity beginning to become more widespread as it begins to move back north from the foothills. Precipitable water value over the area are likely close to .75 inch so weak dynamics is being overcome by deep moisture to aid production of precipitation. RUC and HRRR show this precipitation band moving into southeast Montana and intensifying and while overnight precipitation begins to taper off central and western zones. Timing of precipitation over southeast Montana and weak frontogenesis help amplify snowfall amounts and have put out a Winter Weather Advisory for Carter and Powder River counties where 2 to 4 inches of snow is expected. Further west...including Billings...precipitation will be decreasing while the temperatures get cold enough to change to snow so only expect snow on grassy areas and wet roads. Shortwave ridging on Tuesday dries out the airmass and shifts the precipitation into the Dakotas by afternoon. Temperatures will remain on the cool side as easterly surface flow maintains a light upslope and prevents mixing. Tuesday night into Wednesday a trough moving into the Pacific Northwest increases the mid level flow and causes leeside troughing to developing. The weather remains dry with this regime but downslope flows develop supporting much better mixing and temperatures rebound strongly into the 60s. borsum .LONG TERM...valid for Thu...Fri...Sat...Sun...Mon... Two main weather features on the extended forecast will be on Thursday, and again on Saturday night into Monday. A western upper trough will push into Utah/Nevada early Thursday. This system will spread upper divergent forcing for ascent into northern Wyoming and southern Montana. The core of the system and strongest dynamics will drive well to the south, but will still have adequate moisture available over our area, and thus models were generating roughly 0.25 to 0.50 inches of liquid over parts of southern Montana and north central Wyoming. Have kept likely PoPs over most of the area for Thursday. System is progged to be warm and thus precipitation should mainly be in the form of rain outside of the mountains. Shortwave ridging moves in for Friday, giving a dry and mild day. For Saturday into Monday, models are progging upper troughs to move eastward across the region with chances for showers. The best dynamics again look to track well south of the area, over the central Plains, so precipitation amounts should be light. High temperatures will generally range from the mid 50s to low 60s Thursday-Monday. RMS/Borsum && .AVIATION... MVFR to IFR conditions will continue with rain and snow across the area. Precipitation will likely change to snow later this evening. Mountains will be obscured through tonight. Conditions will improve during the day tomorrow. Reimer/RMS && .PRELIMINARY POINT TEMP/POPS... Tue Wed Thu Fri Sat Sun Mon ----------------------------------------------------------- BIL 032/046 036/067 041/054 034/061 039/060 038/057 035/054 83/S 22/W 36/R 20/U 12/W 33/W 23/W LVM 031/047 036/064 035/054 029/061 037/058 035/056 031/053 52/S 32/W 45/R 21/U 14/W 53/W 33/W HDN 032/050 032/070 039/056 032/063 033/062 036/058 034/056 93/S 21/B 36/R 30/U 02/W 23/W 23/W MLS 032/043 034/066 040/057 035/060 036/061 037/059 035/055 53/S 22/W 14/R 10/U 01/B 23/W 22/W 4BQ 031/040 032/067 039/053 033/059 033/062 037/059 035/055 94/S 21/B 36/R 40/U 00/B 13/W 33/W BHK 026/037 028/056 034/054 031/055 030/057 033/056 033/052 63/S 22/J 14/O 10/B 00/B 13/W 22/W SHR 033/052 036/067 038/051 032/059 033/062 036/058 034/054 81/E 11/B 46/R 40/B 01/B 23/W 33/W && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...Winter Weather Advisory in effect until noon MDT Tuesday FOR ZONES 36-37. WY...None. && $$
Area Forecast Discussion
National Weather Service State College PA
1145 PM EDT Mon Mar 20 2017 .SYNOPSIS... A weakening cold front will pass through the region overnight. A stronger cold front will move through Tuesday night bringing sharply colder air for mid week. Temperatures will moderate toward the end of the week into the weekend. && .NEAR TERM /UNTIL 7 AM TUESDAY MORNING/... Regional radar still shows the remnants of an MCS diving SE through southern Ohio into WV and eastern KY. To the north rain showers are becoming a little better organized over Ontario and the lower Gr Lakes. The HRRR still brings a slug of rain into the region mainly between about 11PM and 4AM, keeping the areal coverage limited and the QPF on the low side. Showers will tend to dissipate toward morning leaving little more than spotty drizzle. Overall I knocked POPS down a bit to better match latest timing. Temps should be mild overnight, running in the 30s. The coldest air up north could lead to a rain/snow mix as the precipitation tapers off late. Little or now accumulation is expected. && .SHORT TERM /7 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/... High pressure will begin to build in for Tuesday. Clouds will likely hang tough over the region for much if not all of the day, but temperatures should be able to rebound a bit and return to near or slightly above normal. && .LONG TERM /TUESDAY NIGHT THROUGH MONDAY/... Secondary/arctic front drops SSE across the region later Tuesday night/Wednesday morning with much stronger cold advection in the upper boundary layer (thanks to nearly orthogonal NW-NNW flow of 25-35 kts to the isotherms in 925-850 mb layer). The base of the subsidence inversion will be quite low (only around 4 kft AGL) and the fetch over the upstream glakes will be relatively short. So, the chance for significant LES will be rather low. However, the shallow strato cu deck will reside within the favorable DGZ thermal ribbon of -12 to -18C, so light accums of snow (up to around an inch) should occur across parts of the NW mtns and Laurel Highlands with just flurries elsewhere. The coldest air we`ll likely see until sometime later next fall will occur Wednesday into Thursday. Daytime highs and overnight lows will be 12-15F below normal. Mins early Thursday will range from near 10F along the PA/NY border, to the lower 20s in the larger metro areas in the Lower Susq Valley as a nearly 1040 mb sfc high drifts overhead. Some lows in the upper single digits will be a good possibility in the perennial cold spots up north. After a partly to mostly sunny and still rather cold day Thursday (by late March standards), clouds will increase Thursday night into Friday as a warm front drifts NE across the commonwealth. Sfc temps, and temps aloft (850 mb) will be a few to several deg C above freezing, so any light precip that occurs with this front will be light. The Warm front will likely lift into New York State and the warm sector should expand NE cover the entire CWA Friday afternoon through most of Saturday with temps surging well into the 40s to around 50F Friday, then into the lower 50s (north) to lower 60s (south) on Saturday. Timing and location of the deep cold air and associated 1040+ sfc high over southeastern Canada will play a key role in the storm track of a southern stream wave that will be sheared east from the Mid Miss Valley late Saturday...through the Ohio River Valley...Central Appalachians and Mid Atl Coast Sunday through Monday. Pops for rain/showers will increase Saturday night through Sunday night, but capped them off in the likely range at this point. Shallow cold air could backdoor us from the NE later in the weekend per the continued/consistent trend of the 12Z EC and GEFS. This could lead to some precip type issues across northern PA at a minimum. && .AVIATION /04Z TUESDAY THROUGH SATURDAY/... Low pressure entering the Ohio Valley this evening will track south of Pa late tonight, spreading rain showers and falling CIGS across the region. Latest HRRR and SREF probability charts suggest IFR conditions are possible between 10Z-14Z at JST/BFD, MVFR conditions are likely at UNV/AOO and perhaps no sig reductions at the lower elevations airfields of eastern Pa, including IPT/MDT/LNS. Any showers should push east of the region around 12Z, as the low pressure system passes off the east coast. However, residual low level moisture ascending the Allegheny Mountains could create lingering MVFR stratocu at BFD/JST into early afternoon. The arrival of high pressure and drier air should result in widespread VFR conditions by late in the day, even BFD/JST. Outlook... Wed-Thu...No sig wx expected. Fri-Sat...Showers/reduced CIGS possible, mainly BFD. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...La Corte NEAR TERM...La Corte SHORT TERM...Dangelo/Ceru LONG TERM...Lambert/Steinbugl AVIATION...Fitzgerald
Area Forecast Discussion
National Weather Service Cheyenne WY
553 PM MDT Mon Mar 20 2017 .SHORT TERM...(This evening through Wednesday night) Issued at 230 PM MDT Mon Mar 20 2017 Forecast challenges deal with precip chances through the short term. Currently...Frontal boundary lays across the southern CWFA, generally from Cheyenne to Shirley Basin to just north of Rawlins this afternoon. AFternoon humidities have been fairly high compared to recent days north and east of the front. Looking at RH values ranging in the mid to upper 30 percent for these areas. South and west of the front, upper teens to low 20 percent reports were common. Radar not showing a whole lot of activity at this time, but short range guidance shows this ramping up later this afternoon. Water vapor imagery showing a pretty strong low off the coast of northern California around 40N 138W that we need to be watching in the long term. Latest run of the HRRR shows a band of showers and isolated thunderstorms developing towards 00Z this afternoon. This looks to be basically along the front from Alliance to Wheatland to maybe Casper. Convection stays north of Cheyenne through the overnight hours, so kept the city fairly dry for tonight. Front continues to slowly lift north through the overnight hours. Though I did not add fog into the forecast for the northern Panhandle and Niobrara County, the evening and mid shift will need to monitor conditions overnight. Forecast soundings showing more of a stratus event than a fog event. Front does south southwest again Tuesday afternoon, so think Cheyenne`s best chance looks to be the tomorrow afternoon. Westerly mid level flow returns Tuesday night into Wednesday, which will force the surface front eastward into the Panhandle. 700mb winds increase to 35-40kts Wednesday afternoon, leading to breezy to locally windy conditions across southeast WYoming. .LONG TERM...(Thursday through Monday) Issued at 230 PM MDT Mon Mar 20 2017 Main focus this period will be with the system that will be moving across the central Rockys late Thursday through Friday. Models have shifted the track a bit farther south thus the main effects from this system look to be over the southeast part of the CWA. main problem will be where pcpn transitions to snow...and how much. Not much cold air associated with the system so snow looks like it will be highly elevation dependent. Snow should fall over the mtns by late Thursday then reach out into the adjacent higher plains Thursday night into Friday morning. Right now looks like several inches of snowfall over the mtns with lesser amounts over the adjacent higher plains of southeast Wyoming. Have undercut guidance temps as they look too warm especially on Friday given clouds and pcpn. Rather windy as well Friday. Clearing friday night with dry and warmer conditions Saturday as an upper ridge slides across the area. Progressive pattern brings the next system to the CWA Sunday with rain and snow showers. Short break early Monday before the next upper system approaches. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 553 PM MDT Mon Mar 20 2017 Scattered light rain showers are moving east across the forecast area this evening and will continue to do so through 09Z or so. Winds across the plains are generally out of the east behind the cold front that moved through earlier. Cigs may drop to MVFR/IFR across the plains in shower activity overnight, and as easterly upslope flow persists through Tuesday morning. Southwest winds look to gust to 25-30kts at KLAR and KRWL Tuesday afternoon. && .FIRE WEATHER... Issued at 230 PM MDT Mon Mar 20 2017 A more unsettled and wetter weather pattern setting up for southeast Wyoming and Nebraska Panhandle. Showers and isolated thunderstorms are possible this afternoon and this evening as a stalled out front interacts with upper disturbances to produce increased chances for wetting rains. This front will stay in the area east of the Laramie Range through Wednesday before being shifted east. For late in the week, a Pacific low pressure system is forecast to track through Colorado, bringing at least a heightened threat for mountain snow and widespread rain to areas along and east of the Laramie Range. In the meantime, afternoon humidities are expected to fall to the low 20 percent range east of the Laramie Range for Tuesday and Wednesday with fair to good overnight recoveries. Fire weather concerns are therefore low through the upcoming week. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None. && $$ SHORT TERM...GCC LONG TERM...RE AVIATION...RJM FIRE WEATHER...GCC
National Weather Service Eureka CA
504 PM PDT Mon Mar 20 2017 .UPDATED DISCUSSION... Extend the wind advisory for 3 more hours through 8 pm this evening for elevations above 2000 feet in SW Humboldt, and Humboldt Interior. High resolution model HRRR shows that the 925 mb level winds of around 45 to 50 kt will persist through this evening before diminishing. This means gusty winds of 40 to 45 mph for ridgetop locations through this evening. /RCL && .PREV DISCUSSION... /issued 339 PM PDT Mon Mar 20 2017/ SYNOPSIS...A frontal system will bring periods of rain tonight through Tuesday. Cold air aloft will result in a slight chance of thunderstorms on Tuesday. A stronger front will arrive Thursday night through Friday, resulting in another round of rain. DISCUSSION...A front just offshore has been producing light to moderate rain through most of the day today. The greatest rain amounts have been over Del Norte and Humboldt counties where a moisture plume has been streaming into the area from the southwest. We will see a brief rain break early this evening, before another front currently crossing 130W merges with the first boundary tonight, resulting in more widespread rain. Locally heavy rain will be possible late tonight as the two boundaries merge and an upper trough pivots toward the North Coast. Instability parameters look favorable for some low topped thunderstorms late tonight, primarily over the waters and near the coast. Winds have been borderline for an advisory, with gusts from 42 to 47 mph over the higher elevations of Humboldt county this afternoon. ARW continues to indicate the potential for gusts up to 50mph over the higher terrain of Humbodlt county through early evening. Therefore will continue with the wind advisory. Breezy conditions will continue tonight into Tue. Advisory level gusts appears unlikely for Tue. Instability and moist onshore flow will result in occasional showers Tue through Tue night. The potential for low topped thunderstorms looks best over the waters, however with daytime heating and steep mid level lapse rates, isolated tstms may also fire up over the interior. The threat for significant hail accumulations appears to be low due to the relatively high freezing levels and low buoyant energy for strong updrafts. The main threat will be lightning activity. The upper trough will finally pass across the area on Wed. There will probably still be showers on Wed, though the frequency and coverage should decrease. Ridging aloft Wed night into Thu morning will result in a period of dry weather. With moist ground conditions, light winds and partially clearing skies, there will probably be some fog in the interior valleys Wed night. A fairly strong front will approach Thursday night and bring yet another round of rain by Friday morning. A period of moderate to heavy rain appears probable as the front moves east across the area. More rock and mudslides are possible during this time frame. Snow levels should remain relatively high during the peak of the rain, above 5kft. Strong wind gusts will also be a factor with this front. Gusts around 50-60 mph will be possible as a low level jet develops along/ahead of the front Thursday Night. Shortwave ridging and drier conditions should follow on Saturday before another front brings another threat of rain for Sunday and perhaps into Monday. AVIATION...A low pressure system will move through the region today and tonight bringing periods of rain and gusty winds. MVFR will generally prevail with periods if IFR in heavier rainfall. In addition to the gusty surface winds, even stronger winds are anticipated just off the surface, which will result in some wind shear at the coastal terminals. Rain will decrease to showers early Tuesday morning and winds should weaken both at the surface and aloft. /RPA MARINE...A low pressure system is bringing gusty south winds to the Northwest California coastal waters today. Buoy observations are indicating gusts to nearly gale force in the southern waters and these gusts should spread north over the next few hours. At this time only localized gusts to 35 kt are expected around Cape Mendocino and Point Arena, so advisory products should suffice. The seas will build in response to the winds and become steep at around 9-10 ft at 6-8 seconds by this evening. Winds and seas will subside late tonight into Tuesday morning only to ramp up again in the northern waters Tuesday afternoon. Another round of small craft winds are anticipated with a few gusts exceeding 30 kt. Winds will become significantly lighter Tuesday night through early Thursday as an upper level ridge moves overhead and the surface pressure gradient becomes weak. Seas will subside back to 5-6 feet by Thursday morning. However, as has been typical this winter, this respite will be short lived as another strong cold front is forecast to approach the waters Thursday and move through Thursday night into early Friday. Again, strong south winds are anticipated with the potential for gales along the leading edge of the frontal boundary. Gale watches may need to be issued Tuesday night or Wednesday for the Thursday-Friday system. /RPA && .EKA WATCHES/WARNINGS/ADVISORIES... CA...Wind Advisory until 8 PM PDT this evening for CAZ104>106. NORTHWEST CALIFORNIA COASTAL WATERS...Small Craft Advisory until 10 PM PDT this evening for PZZ450-455. Small Craft Advisory until 3 AM PDT Wednesday for PZZ470. Small Craft Advisory until 3 AM PDT Tuesday for PZZ475. && $$ Visit us at Follow us on Facebook and Twitter at: For forecast zone information see the forecast zone map online:
Area Forecast Discussion
National Weather Service Louisville KY
1107 PM EDT Mon Mar 20 2017 .Forecast Update... Issued at 1052 PM EDT Mon Mar 20 2017 Have trimmed back chances for showers and isolated thunderstorms this evening based on high-res model trends. Some light echoes have begun popping up behind the front in southern Indiana, but have struggled to maintain themselves. Latest HRRR guidance suggest we could see some light showers develop toward the early morning hours in Central KY. With SPC mesoanalysis showing some elevated instability, could see isolated thunderstorms as well ahead of the front. Otherwise, rest of forecast is on track. && .Short Term (Now through Tuesday Night)... Issued at 259 PM EDT Mon Mar 20 2017 The precipitation from this morning has finally mostly moved out of the region. Warm air advection through the day has contributed to temps rising into the 70s across south and west central KY this afternoon while much of the Bluegrass remains near 50. However, winds have shifted to southerly across the whole area and become gusty this afternoon. This will lead to a surge in temps through the remainder of the afternoon for the cooler areas. Still think that most will see highs at least in the 60s today, though it will come later in the afternoon. Mid to upper 70s for highs are in reach for southwest central KY. As far as precipitation goes, a weak surface low will cross the region this evening and a cold front will sag south overnight. Showers and a few storms will accompany these features, mainly after 0Z tonight. The best chance for precipitation looks to be over the Bluegrass, but even there it still looks to remain scattered in nature. Soundings do show steep mid level lapse rates with a strong inversion at the surface. There looks to be quite a bit of elevated instability, on the order of 1000+ J/kg CAPE, so if storms do form, some hail will be possible. Precipitation should mainly end from the north overnight as the front sinks southward. A few showers and storms could linger into tomorrow morning across south central KY, but most areas look to be dry. Another shortwave moving through the upper level flow will approach and move through tomorrow afternoon into the evening. This will bring a renewed chance for showers and storms, particularly across south central KY, though the area of highest coverage does look to be a bit further to the south than in previous model runs. The storms across south central KY could become strong to marginally severe in the afternoon and evening with hail and some gusty winds. Precipitation looks to finally end tomorrow night. Temperatures tonight will remain on the warm side ranging from the upper 40s across southern IN to the mid to upper 50s across south central KY. Highs tomorrow look to be in the 60s with lows back into the 30s tomorrow night. .Long Term (Wednesday through Monday)... Issued at 308 AM EDT Mon Mar 20 2017 Mainly dry weather is expected from midweek through the end of the work week. Surface high pressure will build in from the north on Wednesday. Temperatures will be on the cooler side Wednesday with highs in the mid 40s to mid 50s. Through the end of the week, upper level ridging will build in. A warm front will move north across the region on Thursday. The GFS/ECMWF then show a disturbance rounding the top of the upper ridge on Thursday evening and possibly bringing showers to the Bluegrass region. Will carry just low end pops with this due to the uncertainty associated with it. Temperatures will quickly rebound back into the 60s to lower 70s by Friday. The weekend continues to look wet as a deep upper level low slowly approaches and moves from the Midwest into the Great Lakes region. Showers and storms look to move in from the west Saturday morning as we sit solidly in the warm sector of the system. Precipitation will overspread the area through Saturday into Saturday night. We could still see scattered showers Sunday behind the front. These look to move out Sunday night. The more spring-like temperatures will continue this weekend with highs in the 60s to lower 70s. && .Aviation (00Z TAF Update)... Issued at 750 PM EDT Mon Mar 20 2017 Regional radar shows two clusters of storms, one passing to the southwest of BWG and the other to the northeast of LEX. In between these two areas of convection, VFR conditions will prevail, at least over the next two hours. A surface boundary that has been slipping south is currently draped over the Lower Ohio Valley. Expect ceilings to gradually lower to MVFR and then to fuel alternate levels overnight. Isolated showers and storms are expected to flare up as well, primarily affecting SDF and LEX. Post-frontal low level moisture is expected to maintain low ceilings into Tuesday morning. Fuel alternate levels look likely, especially after 05z, and a dip to IFR isn`t out of the question. Winds will be erratic overnight with the cool front moving through, but around 5 kts or less. An increasing northerly breeze behind the front will help ceiling and visibility restrictions lift during mid to late morning. Shower and thunderstorm chances will return to BWG Tuesday afternoon and evening. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...None. KY...None. && $$ Update...DM Short Term........EER Long Term.........EER Aviation..........EBW
Area Forecast Discussion
National Weather Service Morristown TN
940 PM EDT Mon Mar 20 2017 .DISCUSSION...Another quick update this evening to raise POPs to account for incoming activity out of Southern Middle TN. Latest HRRR and RAP runs bring this activity further into our CWA than previous runs. New runs still show this activity weakening and dissipating by around midnight. Will continue to monitor this area of showers and storms as it moves in. Will send new zones for POP adjustment. && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 55 77 54 64 / 20 60 70 30 Knoxville McGhee Tyson Airport, TN 49 72 48 58 / 30 70 80 20 Oak Ridge, TN 52 72 49 61 / 40 60 80 20 Tri Cities Airport, TN 49 68 45 57 / 50 50 70 20 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...None. TN...None. VA...None. && $$ SR
Area Forecast Discussion
National Weather Service Raleigh NC
1030 PM EDT Mon Mar 20 2017 .SYNOPSIS... A warm front will push northward through the area tonight, bringing mild air for Tuesday. A cold front will push slowly southward through the area Tuesday evening through Tuesday night. Cool high pressure will build into the region from the north Wednesday through Thursday. && .NEAR TERM /Through Tonight/... As of 1030 PM Monday... Earlier update is on track. The earlier MCS over S OH has weakened considerably as it has crossed WV and become farther removed from the best wind fields and moisture flux. The residual area of showers (and a couple of isolated embedded storms, although these too will weaken) will continue a slow decrease in coverage and intensity, following the HRRR and WRF-ARW, but still expect enough showers across the far N and NE CWA to keep chance pops, highest near the Kerr Lake and Lake Gaston areas. Lows from the upper 40s east to lower 50s west. -GIH Earlier discussion from 730 pm: Forecast was updated to account for greater shower chances across the north and NE tonight, along with greater cloud cover (earlier increase from NW) and warmer temps tonight. The MCS covering southern OH (including a bow echo tracking along the Ohio River) is on track to cross WV into VA over the next several hours, following the mean steering flow, although as it does so, it will move out of both the low level theta-e ridge and low level jet nose, and this loss of support should result in a decrease in intensity and coverage of showers as it approaches far north- central and northeast NC late tonight. That said, however, the HRRR/RAP/WRF-ARW, as well as the latest GFS/NAM/ECMWF, all show a batch of scattered showers crossing the NE CWA very late evening into the overnight hours. Have raised pops late evening through tonight from the Triangle N and E, with good chance near Kerr Lake and Lake Gaston. This should be mostly showers by that point, especially given the lingering lower dewpoints and cooler temps over the NE CWA, where mid level lapse rates will still be under 6 C/km. With a faster and greater increase in cloud from the west and NW this evening, hindering radiational cooling, have bumped up lows to around 50 / lower 50s, except for upper 40s east of Highway 1. -GIH Earlier discussion from 100 pm: Low-level moisture will increase from the W/WNW tonight as the aforementioned front progresses slowly south/east into TN/WV/VA and low-level flow strengthens downstream in the Carolinas. Model guidance is fairly unanimous in showing measurable precipitation in the N/NW Piedmont late tonight (06-12Z Tue). Model guidance is most likely picking up on remnants of the MCC, e.g. the eastern portion of the complex as it progresses S/SE through WV into southwest VA overnight. Alternately, strengthening low-level warm advection may result in marginal/elevated destabilization and a potential for elevated showers at the leading edge of a 925 mb warm front lifting NE from Upstate SC through the Foothills/Western Piedmont of NC between 06-12Z Tue morning. Given the dry airmass (PWAT 0.20-0.40") currently in place east of the mountains, confidence remains low with regard to whether or not sufficient moistening/elevated destabilization and/or sufficient forcing will be present to maintain lingering MCC remnants or support the development of elevated showers late tonight. At this time, will continue to indicate a ~20% of showers after midnight across the W/NW Piedmont. Given broken/overcast cloud cover and a SW breeze, expect lows Tue morning to be much warmer than this morning, in the mid to upper 40s, coldest in the E/NE Coastal Plain. -Vincent && .SHORT TERM /Tuesday and Tuesday Night/... As of 216 PM Monday... A broad surface low and associated cold front progressing SE into the Appalachians tonight will track slowly southward through central NC as a backdoor cold front late Tue aft/eve into Tue night, in the presence of small amplitude shortwave energy traversing the region in NW flow aloft. Aside from elevated convection that may develop over or propagate into portions of central NC early Tue morning, expect dry conditions to otherwise prevail through mid Tue afternoon given weak forcing and a strong capping inversion associated with a pronounced elevated mixed layer (H7-H5 lapse rates ~8c/km) advecting into the Carolinas from the west. Expect highs Tue afternoon in the mid/upper 70s to lower 80s. By late Tue afternoon, convection is expected to develop over and/or propagate into central NC from the west as the cap weakens via diurnal heating and forcing strengthens as the low/cold front progresses southward into central NC and shortwave energy traverses the region in NW flow aloft. The latest guidance suggests the potential for convection will be greatest along/south of Hwy 64 between 21Z Tue afternoon and 06Z Wed morning. Lows Tue night will be driven by cold advection in the wake of the front, ranging from the mid 40s (N) to lower 50s (S). Severe Potential: Very steep mid-level lapse rates, Spring insolation and seasonable low-level moisture (dewpoints rising into the mid/upper 50s) will yield as much as ~1000 J/kg of MLCAPE late Tue aft/eve, in the presence of deep layer shear sufficient for supercellular organization. With the above in mind, deep convection that develops and/or propagates downstream into central NC Tue aft/eve will have the potential to become severe, with a primary threat of large hail and damaging winds. The threat for severe weather will be greatest (relatively speaking) south of the Highway 64 corridor between 5pm and Midnight. -Vincent && .LONG TERM /WEDNESDAY THROUGH MONDAY/... As of 325 PM Monday... Surface cold front and attendant axis of deeper moisture will push south of the area by daybreak. Rain/showers should be exiting southern portions of the forecast area by the morning rush hour commute, with NW-SE post-frontal clearing during the late morning/early afternoon, as the leading edge of the strong Canadian high builds in from the north. Highs Wednesday a good 15 to 20 degrees cooler than Tuesday, ranging from lower to mid 50s NE to lower 60s SW. With the cP airmass centered over the area Wednesday night through Thursday night, temperatures through the period will average a good 10 to 15 degrees below normal. Thursday morning looks to be the coldest morning, with most area at or below freezing, lows in the upper 20s to lower 30s. Highs in the 50 to 55. The Nam is a wet outlier in the depiction of spreading precip into the area Wednesday night and into the day on Thursday, in response to shortwave disturbances moving through the area. The remainder of the NWP guidance keeps this overrunning precip suppress south of the area and thus will keep forecast dry. The modified Canadian parent high will shift offshore on Friday, with southerly return flow allowing for a quick moderation to 70 degree readings by Saturday with ridging aloft keeping it dry through Friday night and possibly through much of the day on Saturday. Strengthening warm moist air advection on the eastern periphery of the closed mid/upper level cyclone moving east-northeast into the Ohio Valley will result in increasing chance of showers and possibly a few thunderstorms late Saturday and into the day on Sunday. The closed cyclone is forecast to gradually weaken as it moves east- northeast, and thus the threat for severe weather is minimal at this time. Continued mild with highs in the 60s and 70s. Lows in the upper 40s and 50s. && .AVIATION /00Z Tuesday through Saturday/... As of 745 PM Monday... 24 Hour TAF Period: Medium confidence of VFR through the TAF period with SSW/SW winds becoming more variable and light overnight. Scattered to broken clouds near 5 kft can be expected into the overnight hours giving way to higher ceilings later Tuesday afternoon. Light precip at the northern terminal sites is possible between 6 and 12Z Tuesday morning as a disturbance moves along the VA border. No thunder is expected with the precipitation at this time. Other than a brief period of gusty winds (15-20 kts) at KFAY late tomorrow morning into early afternoon, winds at most terminals should remain variable between 5-10 kts. Long Term: There will be another chance for precipitation at KFAY just after the TAF period as a disturbance passes just south of the forecast area. Otherwise expect mainly VFR conditions through much of the period. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Hartfield NEAR TERM...Hartfield/BV SHORT TERM...Vincent LONG TERM...CBL AVIATION...BB/Ellis
Area Forecast Discussion
National Weather Service Charleston WV
1042 PM EDT Mon Mar 20 2017 .SYNOPSIS... Cold front with showers and thunderstorms crossing the area. Upper disturbance passes Tuesday night. High pressure Wednesday night and Thursday. Warm front Friday. Cold front over the weekend. && .NEAR TERM /THROUGH TUESDAY/... As of 1030 PM Monday... Another PoP tweak due to shower/tstorm development over Ohio. As of 820 PM Monday... Updated PoPs and wind to better reflect radar trends and HRRR guidance. Current batch of showers and thunderstorms moving through the area is generally not causing any issues with precip gages coming in at near a 1/2". A second band of showers is developing over Ohio and looks to also cross tonight. Again, no issues expected. Zonal upper level flow quickly rushes impulses through the region with on/off PoPs over the next 24 hours. && .SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/... As of 420 AM Monday... Tuesday morning finds a cold front at least half the way through the forecast area, and an upper level wave moving off to the east. The cold front slips southward, through the remainder of the area, by Tuesday afternoon, taking any showers with it. Left a small chance for thunder in the extreme south midday Tuesday, just before the front moves through there. Models show a flat wave moving across the area Tuesday Night, bringing about a renewed chance for precipitation. Given the sloping baroclinic zone on the north side of the front south of the area, we are looking at mainly mid and upper level moisture and hence light precipitation. The colder air moving in behind the front may allow a transition from rain to snow from north to south overnight Tuesday night into Wednesday morning, with very light accumulations possible in the mountains. Cloud temperatures favoring crystal growth and dry air below the cloud base favor a transition of any precipitation to snow during this time. Strong high pressure featuring cold and very dry air dominates Wednesday afternoon through Thursday, as it passes north of the area. Temperatures close to central guidance including a very cold Thursday morning, about ten degrees below normal, for a hard freeze for any agricultural interests. && .LONG TERM /FRIDAY THROUGH MONDAY/... As of 420 AM Monday... Warm advection precipitation may scoot across northern portions of the forecast area Thursday night into Friday. The retreating cold air may hang on long enough for snow furthest east, across northeastern WV. The area breaks out into a warm sector Friday afternoon into Saturday. A cold front approaches later Saturday and is likely to cross later Saturday night or Sunday, ahead of which thunder is possible. Low pressure approaching from the west on Monday may lead to a continued or renewed chance for precipitation. Have lows occurring early Thursday night as warm advection develops overnight. Otherwise temperatures close to central guidance, which is a little below the MEX over the weekend. && .AVIATION /03Z TUESDAY THROUGH SATURDAY/... As of 1040 PM Monday... Largely VFR becoming more MVFR and eventually IFR in places as a cold front moves through though believe this forecast is a bit pessimistic. IFR possible in tstorms, but not confident enough to put in TAFs. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z WEDNESDAY... FORECAST CONFIDENCE: Medium ALTERNATE SCENARIOS: Timing of any showers or isolated thunderstorms, and resultant MVFR or worse conditions may vary from forecast. EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY OF WFO FORECAST TO AVAILABLE MODEL INFORMATION: H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS. L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. DATE TUE 03/21/17 UTC 1HRLY 03 04 05 06 07 08 09 10 11 12 13 14 EDT 1HRLY 23 00 01 02 03 04 05 06 07 08 09 10 CRW CONSISTENCY H H L H H H H H M M M L HTS CONSISTENCY H H H M M M M M M M H M BKW CONSISTENCY H H H M M M L L L L L L EKN CONSISTENCY L H H M L M H L L M H L PKB CONSISTENCY M M H M M M H H H H H M CKB CONSISTENCY H M M M L L M M M M M L AFTER 00Z WEDNESDAY... No IFR expected. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...None. OH...None. KY...None. VA...None. && $$ SYNOPSIS...ARJ/JW/DTC NEAR TERM...JW/DTC SHORT TERM...ARJ LONG TERM...ARJ AVIATION...JW/DTC
Area Forecast Discussion
National Weather Service Blacksburg VA
852 PM EDT Mon Mar 20 2017 .SYNOPSIS... Weak low pressure will push east across the Appalachians overnight, triggering showers and isolated thunderstorms as a warm front lifts across the mid Atlantic states. As the low progresses east, a cold front will push south across the area Tuesday as high pressure builds in from the upper Midwest for the middle of the week. && .NEAR TERM /THROUGH TUESDAY/... As of 845 PM EDT Monday... MCV driven complex of showers and storms along the nose of the 850 mb theta-e axis continues to approach from the northwest this evening and expect the initial band to cross the mountains in the next hour or two. Appears main batch of more organized coverage will clip the northwest as well through midnight with a trailing line feature perhaps reaching the far southwest zones as well before fading. Just how widespread/strong the showers/storms will be remains iffy as evening soundings show support for elevated convection above the dry near surface inversion while surface instability remains about nil. Latest HRRR tends to fade coverage crossing the ridges but doesn`t have much of a handle on the trailing band to the southwest. Since more of a dynamic system would expect shra/tsra to go further than model guidance despite loss of heating. Thus upped pops a bit sooner to categorical northwest while extending the likelys farther south over the next few hours. Also appears feature will exit sooner after midnight with showers fading out east with possibly a few bands redeveloping far southwest where kept higher pops while trimming eastern half shortly after midnight. Some upward adjusts to temps overnight given moistening dewpoints with lows mostly in the 40s to around 50. Previous discussion as of 345 PM EDT Monday... Currently keeping an eye on a complex of showers and thunderstorms over central Indiana which are associated with a low pressure system that is advancing up the Ohio River Valley this afternoon. Weather forecast models are in good agreement that this low will pass across the central Appalachians overnight, with the associated showers and possibly isolated thunderstorms advancing to the Interstate 64 corridor shortly before midnight. Believe this convection will begin to diminish as it drifts southward toward the North Carolina/Virginia state line as winds in the wake of the cold front dragging behind the low shift increasingly westerly and downslope. Despite frontal passage, cold air does not yet truly enter the area, and overnight low temperatures will hold in the 40s nearly areawide. Through late Tuesday morning, expect residual rain shower activity to linger along the ridges of southeast West Virginia through the highlands of North Carolina, as well as in the vicinity of the passing cold front south of Highway 460 across the Piedmont. Latest forecast model solutions have become a little faster with the passage of the front, indicating less instability than previously called for along the southern end of the forecast area during the afternoon where temperatures are expected to rise into the 70s. Still, cannot rule out a slight chance of thunderstorms from late morning through mid afternoon across the south, though instability will be minimal. Scattering of clouds during the afternoon will promote high temperatures in the low/mid 70s across the Piedmont, while areas along and west of the Blue Ridge will hold in the 60s. && .SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/... As of 300 PM EDT Monday... Models are trending faster and further to the south with a west-to- east oriented frontal passage Tuesday night. Even though models have most of the area dry by midnight, we decided to cut PoPs by half going from 60 percent to 30 percent. The highest PoPs remain along the VA/NC border south. The dew point front lags behind with the colder, drier air not entering the northern portion of the CWA (Lewisburg Wv-Lynchburg VA) until around sunrise Wednesday morning. Therefore, leaned toward the warmer MET guidance Tuesday night with most areas staying above freezing with the exception of higher ridges across Greenbrier County to the Alleghany Highlands. Moisture should be gone by the time cold air filters into the area Wednesday to limit accumulating snow to these ridges. High pressure will build in from the north Wednesday. The coldest air should not sink south until Wednesday evening as the center of the high wedges south across the piedmont. Wednesday temperatures will range from the upper 40s to lower 50s west to upper 50s-lower 60s east Wednesday. Cold air Wednesday night will send temperatures down into the mid to upper 20s across the forecast area. We will see uniform temperatures Thursday in the upper 40s to lower 50s as dry cool wedge engulfs the region. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... As of 300 PM EDT Monday... Cool wedge of high pressure will begin to move off the VA/NC coast Thursday night. As the center of the wedge tracks east, a warm front will push moisture over the mountains which should only result in an increase in cloud cover Friday and Friday night. However, a bubble high will likely remain east of the Blue Ridge and over the foothills and piedmont counties into Friday night. This bubble of cool air and easterly flow will keep high temperatures east of the Blue Ridge close to 60F while the mountains warm into the lower to mid 60s. The wedge should be completely erode out of the region by Saturday afternoon with temperatures warming into the mid 60s to lower 70s across the forecast area. An area of low pressure is expected to track from the Midwest Saturday night towards the Ohio Valley Sunday. This system has the potential to bring severe weather to the region Sunday and Sunday night. The track of the system and timing of prefrontal convection into the region will be the biggest influence on how widespread severe potential may become. && .AVIATION /00Z TUESDAY THROUGH SATURDAY/... As of 745 PM EDT Monday... Slow moving front approaching from the northwest is acting as a focus for elevated convection in the Ohio valley at nose of low level jet. Expect the convection to sink into the region from the north in the next hour or two, and expect enough forcing with modestly steep mid/upper lapse rates to support mention of thunder. The front is in no hurry to clear the region and expect lingering showers mainly in the west to persist through most of the overnight period. The lingering boundary will also start to generate new convection south and west later tomorrow but it does not appear likely to affect TAF sites so will maintain a dry forecast for Tuesday. The flow will become northwesterly behind the front and combine with low level moisture to generate upslope MVFR/IFR low clouds mainly west of the Blue Ridge late tonight into Tuesday morning. Believe the lower cigs will hang in for most of the day in the west, while sites east of the Ridge should become VFR toward daybreak and remain as such through Tuesday. Expect winds to generally remain light through the period. Extended Aviation Discussion... High pressure builds in for Wednesday which should improve ceilings back to VFR. By Thursday the high will wedge in from the northeast, so will remain mainly VFR. It is possible that residual lower ceilings may get trapped especially along and east of the Blue Ridge Wednesday night into Thursday, resulting in possible MVFR ceilings. Dry and warmer weather is expected on Friday. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...JH/NF NEAR TERM...JH/NF SHORT TERM...RCS LONG TERM...RCS AVIATION...MBS/NF