Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 100839 AFDAKQ AREA FORECAST DISCUSSION National Weather Service Wakefield VA 339 AM 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 330 AM EST Tuesday... Latest MSAS show a weak frontal systm nearly stnry ivof the I95 corridor depicting a warmer and more humid airmass to the east of it with a cooler (wedge like) airmass to the west despite a sw wind flow. Meanwhile, low pressure is tracking ne ivof Lake Huron with its trailing cold front extending sw across Ohio/Tn/Ky. Rather interesting fcst next 24 hrs with rapid changes expected ranging from near record high temps across the se today to some minor wet snow accumulations across the nrn most zones Wed morning. Models not showing much support for pcpn thru 15Z. Given only mid-high level clouds east of the bndry, expect temps to rise due to prtl sun. Clouds west of it will keep temps in check today. Models actually show a narrow band of convective shwrs developing along the stalled frontal bndry ivof the I95 corridor by 18Z, then tracking se across the area thru 00Z. While thunder chcs remain rather low (and not in the grids), would not be surprised to see an elevated lightning strike as this line punches into the warmer and more humid airmass across the se later today. Otw, post-frontal shwrs dvlp with PoPs ramping up by 21Z. Temps tricky and will all depend on the location of the bndry. A large temp range expected from highs near 60 ivof LKU to the upr 70s at ECG. Most record highs today are safe, except for ECG. See CLI section below. && .SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/... As of 3330 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 MONDAY/... 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 /09Z TUESDAY THROUGH SATURDAY/... As of 1230 AM EST Tuesday... The local area in btwn systems attm as the first wave of low pressure moves ne of the area and ahead of the moisture assctd with the apprchg cold front progged to cross the area this eve. The low clouds are scouring out due to somewhat drier air and gusty sw winds behind the departing s/w to the ne. VFR CIGS already noted across the se with RIC/SBY expected to scour out the lower stratus during the pre-dawn hours. Models show the shwrs ahead of the apprchg cold front cross the area after 18Z with more widespread stratiformed rain expected behing the fropa after 00Z. Thus, the forecast will show lwrg CIGS/VSBYS after 00Z along with a wind shift to the north. OUTLOOK... A large area of post-frontal light to moderate rain will track across the area Tuesday night before ending from W to E during the day on Wednesday. Flight restrictions are likely during this timeframe. There is a 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. Pcpn should stay in the form of RA at the sern terminals. High pressure builds into the area Wed/Thurs, allowing VFR/dry conditions to return. Another area of low pressure brings rain and degraded flight conditions Friday into Friday night, with the potential of a brief RA/PL mix during the onset at RIC. Weak high pressure builds in from the W Saturday. && .MARINE... As of 330 AM EST Tuesday... In the near term, existing Small Craft Advisories for the Chesapeake Bay, Lower James, and Currituck Sound that originally went into this afternoon have been cancelled. South to southwest flow over cooler waters (Bay temps in the upper 40s) has made it difficult for many 20 knot+ gusts to mix down to the surface this morning. Cannot rule out a few gusts to 20 knots at the typical elevated locations, but do not expect this to be widespread/frequent enough to continue the existing SCAs. SCAs for the coastal waters have been maintained due to seas at or above 5 feet. SW winds continue through the day today, generally in the 10 to 20 knot range. A cold front crosses the waters beginning later this afternoon, which will turn winds to the NW and then N, and wind speeds increase into the 15 to 25 knot range with gusts to as high as 30 knots. These elevated winds will continue into Wednesday afternoon for portions of the waters as much cooler air filters into the region. As a result, SCAs are now in effect for the Chesapeake Bay, Lower James, and Currituck Sound beginning this evening and continuing into Wednesday. Seas remain elevated through this period, at or above 5 feet, thus SCAs for the coastal waters have also been extended to take this in account. Winds relax Wednesday afternoon, before a reinforcing shot of cold air arrives later Wednesday night into early Thursday morning as a strong area of high pressure builds into the region. Winds will once again increase to 15 to 25 knots, and another round of SCAs will likely be needed for at least the Chesapeake Bay and lower rivers. The area of high pressure settles over the region by Thursday afternoon. Conditions for Friday into Saturday are uncertain from a timing stand point as the flow turns NE then E as a wave of low pressure develops over the SE US and lifts into the Mid-Atlantic States. But would expect SCA conditions with the easterly flow and likely elevated seas. && .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 from 7 PM this evening to 1 PM EST Wednesday for ANZ632-634. Small Craft Advisory from 10 PM this evening to 4 PM EST Wednesday for ANZ633. Small Craft Advisory from 7 PM this evening to 10 AM EST Wednesday for ANZ630-631. Small Craft Advisory from 10 PM this evening to 10 AM EST Wednesday for ANZ638. Small Craft Advisory until 4 PM EST Wednesday for ANZ650-652- 654. Small Craft Advisory until 7 AM EST Thursday for ANZ656-658. && $$ SYNOPSIS...MPR NEAR TERM...MPR SHORT TERM...MPR LONG TERM...MPR/JAO AVIATION...MPR MARINE...AJB CLIMATE...MPR

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