Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 101929 AFDAKQ AREA FORECAST DISCUSSION National Weather Service Wakefield VA 229 PM EST Tue Dec 10 2019 .SYNOPSIS... Low pressure tracks into eastern Canada today with the trailing cold front crossing the local area this evening. High pressure returns Wednesday and Thursday. Low pressure develops along the Gulf Coast Friday before approaching the area this weekend. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... As of 1040 AM EST Tuesday... Late morning upper air analysis shows broad upper troughing over the Plains/Midwest, with ridging well off the SE CONUS coast. At the surface, strong low pressure was over Quebec, with ~1029 mb high pressure over the nrn Plains. A strong (trailing) cold front was draped from Quebec SSW to the ern Gulf Coast. Across our local area, the flow was out of the SW at the surface and aloft. There are a few pre-frontal showers over north/west zones, but it is mainly dry elsewhere. Skies are BKN-OVC across the Piedmont, with partly-mostly cloudy skies over the SE half of the CWA. It has already warmed to near 70F across SE VA/NE NC, with 60s from central VA to the Lower MD Ern Shore. Temperatures are still in the upper 50s across the Piedmont. As the front approaches the region this aftn...the coverage of showers will increase (some) from W to E. Have PoPs ramping up to 60% by the mid-late aftn in most areas (except for far SE VA/NE NC...where PoPs increase to 30-50% by 21z). Consensus of near-term/hi-res guidance has the front positioned from central NC to SE VA by early evening. Not everyone will see rain this aftn, but QPFs (through 00z) will average 0.10" or less. Highs range from near 60F near LKU to the upper 70s at ECG. Most record highs today are safe, except for ECG. See Climate section below. && .SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/... As of 330 AM EST Tuesday... The cold front pushes east across the area late aftrn/erly eve. Data continue to show strong 850-700 mb frontogenesis through the night as the mid-level trough axis remains to our W. Pcpn type becomes stratiformed in nature with near 100 PoP for a decent soaking of rain (QPF 1/3 to 1/2 inch). As the night wears on, thicknesses crash along with a quick temp drop. With pcpn continuing past 12Z, expect the rain to become mixed with wet snow across the nrn third of the fa aftr 09Z. Once again, this to be an event much like the mid Nov wet snow where pcpn intensity will determine whether the pcpn can change over to all wet snow long enuf to drop the temp (33-34 degrees) for a light accum to occur. Believe this to be the case across nwrn most zones where accumls of arnd one half inch will be noted. Expect a rain/wet snow mix as far south as a Cumberland-RIC-XSA-SBY line. Little to no accumls expected thru the Wed morning commute here as sfc/wet bulb temps remain above 32. All rain across the south with lows in the upr 30s-lwr 40s. Decent lift conts Wed morning before quickly shutting off after 18Z as drier air to the west pushes the pcpn offshore. Kept likely-cat PoPs thru 15Z with a mix of rain/wet snow across the nrn most zones. Rain south. Expect the pcpn to go back to a cold rain by late morn as intensity becomes lighter and temps slowly inch up. Pcpn ends and pushes offshore after 18Z. Dcrg aftrn clouds across the west. Not much rise in temps given the clouds and CAA. Highs Wed low-mid 40s. A 1040 mb high tracks across Ohio Wed nite / PA Thurs to a psn near BOX by 00Z Fri. Mstly clr Wed nite with a secondary CAA surge noted. Lows in the 20s to lwr 30s se. Sunny/cold Thurs. Went below guid for high temps. Highs upr 30s-lwr 40s except mid 40s sern coastal areas. Models show the high is slower to push east Thurs nite. This in turn slows the advancing moisture from the dvlpng systm to the south. Thus, will indicate increasing clouds by kept it dry thru 12Z Fri (per latest GFS/ECMWF solns). Lows may occur early then level off or rise a bit as the clouds come in. Lows upr 20s nw-lwr 40s se. && .LONG TERM /FRIDAY THROUGH TUESDAY/... As of 330 AM EST Tuesday... The high is slow to depart Fri while a significant srn stream systm is progged to dvlp along the Gulf Coast states before lifting ne along the ern seaboard over the weekend. The 00Z GFS conts to be the faster model in bringing overrunning pcpn across the wrn zones Fri morning, while the 00Z ECMWF holds off any pcpn until after 18Z. Given these changes, made some adjustments to Fri fcst. Mainly to slow the onset of pcpn down by svrl hrs. This allows temps to rise above 32 in most areas for mainly a cold rain. However, did keep a few hr prd of fz rain at the onset (per thicknesses) across Louisa/Fluvanna county. Otw, rain overspreads the local area Fri. Highs low-mid 40s across the Piedmont (insitu-wedge) to 55-60 along the coast. The wet period extends into the weekend with the GFS and ECMWF in better agreement. The wettest period look to be from late Friday into early Saturday. Will increase PoPs from the south/southwest during the day on Friday but the bulk of the precip is expected to fall Friday night into early Saturday as low pressure lifts northward across the region with the models in agreement. Conditions Sunday look mostly dry with some cloud cover. High temps on Friday range from the low 40s NW, close to 50 degrees for the Richmond metro, and low to mid 50s for areas east of I-95. Not looking particularly cold behind the weekend system either, highs in the 50s Saturday and Sunday with lows in the upper 30s and low 40s. && .AVIATION /19Z TUESDAY THROUGH SUNDAY/... As of 1245 PM EST Tuesday... VFR conditions prevail early this aftn across the sern terminals, while MVFR CIGs have been observed at RIC/SBY. A cold front is approaching the VA Piedmont as low pressure tracks eastward across Quebec. Ahead of the front, showers have developed across central VA/the VA Piedmont. These showers will impact RIC/SBY off and on through the aftn. As the front crosses the area from west to east, the showers will approach PHF/ORF later this aftn. However, pcpn likely holds off at ECG until late aftn/early evening. While prevailing VSBYs likely remain VFR, brief MVFR (or even IFR) VSBYs will be possible in these showers. Showers likely continue through the evening...but there may be a few breaks in the rain before 02-04z. The front is expected to move S of the terminals by 03z or so. After that, more widespread, post-frontal (stratiform) rain is expected through tonight. Thus, the TAF forecast will reflect CIGs lowering from MVFR to IFR tonight in addition to RA (VSBYs mainly between 2-4SM). Gusty SW winds (20-25 kt near the coast) shift to the W, NW, then N this aftn-tonight. N winds could gust to ~20 kt later tonight. There is an increasing chc that pcpn changes over to PL/SN Wed AM before ending at SBY, with a slightly lesser chc of PL/SN at RIC. Not expecting much in the way of impacts from wintry pcpn, but introduced a mention of mixed pcpn in the TAFs for RIC/SBY (mainly from 09-14z Wed). Pcpn should stay in the form of RA at the sern terminals. Pcpn ends from W to E from Wed AM-midday (at the latest). IFR CIGs improve to MVFR Wed AM before rising to VFR/scattering out by aftn. OUTLOOK...High pressure builds into the area late Wed-Thurs, allowing VFR/dry conditions to return. Another area of low pressure brings rain and degraded flight conditions Friday through Saturday. && .MARINE... As of 220 PM EST Tuesday... Cold front will slowly cross the waters through this evening shifting winds from WSW to NW. Speeds avgg 10-20 kt prefrontal then some decrease w/ and shortly behind the front. Low level CAA kicks in by late this evening...through the overnight and Wed morning before waning. Due to the CAA...speeds to increase to 15-25 kt...w/ 30 kt possible(for a brief period) over the lower Ches Bay and the ocean. Winds diminish Wed afternoon. A second surge of low level CAA expected Wed night (that does appear to be a bit weaker than the first one tonight) before sfc hi pres finally builds over the local waters. That sfc hi pres drifts off to the NE Thu-Thu night. Lo pres begins to develop INVOF Gulf of Mexico Fri then tracks NNE near the mid-Atlantic coast by Sat morning which may result in increased winds and deteriorating wx conditions over the waters heading into the weekend. SCAs will be up for all of the waters except parts of the VA Rivers (though even those areas may have a brief period of near SCA conditions - winds gusting to 20 kt). SCAs to come down during Wed for the Ches Bay...sound and lower James River then will likely be needed again Wed night/early Thu. For the ocean...SCAs will be up into Thu morning (N) and through Thu afternoon (S) as seas will remain aoa 5 ft. && .CLIMATE... Record highs for 12/10: RIC...79 in 2007 ORF...78 in 2007 SBY...73 in 1966 ECG...78 in 2007 && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...Small Craft Advisory until 1 PM EST Wednesday for ANZ632-634. Small Craft Advisory until 4 PM EST Wednesday for ANZ633-650- 652-654. Small Craft Advisory until 10 AM EST Wednesday for ANZ630-631- 638. Small Craft Advisory until 7 PM EST Thursday for ANZ656-658. && $$ SYNOPSIS...MPR NEAR TERM...ERI/MPR SHORT TERM...MPR LONG TERM...MPR/RHR/JAO AVIATION...ERI MARINE...ALB CLIMATE...

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