Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 132055 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 355 PM EST Fri Jan 13 2017 .SYNOPSIS...
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A cold front will stall over the Carolinas tonight as high pressure builds east from the Great Lakes. The high will weaken over New England on Saturday, as low pressure lifts northeast through the mid Atlantic region. Another high pressure system will become centered from the Great Lakes to New England Saturday night through Monday as the frontal boundary remains nearly stationary across the southeast states.
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&& .NEAR TERM /THROUGH SATURDAY/...
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Latest analysis indicating sfc cold front now south of the CWA and pushing through central/southern NC with strong/1045mb sfc high pressure centered over the Great Lakes. N/NE low level flow prevails locally, but temperatures have been fairly slow to fall, especially across interior northeast NC and south central VA where readings are still in the 60s (most locations are now in the 50s). Enough dry air is pushing in from the N so that there will be some breaks in the clouds into the early evening hrs. Later tonight, as the strong high pressure system continues to drift E from the Great Lakes to New England, a trough of low pressure lifts ENE from the TN Valley to the central Appalachians. 13/12Z guidance overall has trended a bit warmer than last night`s 00Z runs (which makes sense given today`s temperatures). Expecting light overrunning precipitation, with GFS/NAM 295K surfaces spreading the overrunning moisture across the northwest half of the local area toward the Maryland Eastern Shore mainly after 06Z. Enough low level cold air arrives late (mainly below 900mb) to bring a chance of rain/freezing rain/sleet across the far northern forecast area (but have trended the forecast warmer and expect sfc temperatures to be above freezing as the precip begins (in most cases well above freezing). 850Mb temps expected to stay between +3 to +5C, except will fall to +1 to +2C across the MD eastern shore. Best chances for light rain to possibly transition to light freezing rain for a few hrs would be over the far N of the CWA, from Louisa to Caroline Co. and interior northern Neck counties from about 10-12Z. The warm nose aloft might be too shallow over the eastern shore for any freezing rain (thinking more sleet or a rain/sleet mix with temperatures staying above freezing there). From 12-15Z, as mid level warming aloft pushes a bit more to the NE, could see a brief period of light freezing rain mixed with sleet or plain rain over the MD eastern shore. Still appearing very marginal as sfc temperatures will likely have to column cool just to get down to 32 F (and if precip stays too light temperatures may remain above 32 F for the entire event). Also, ground and roads should be well above 32 F due to the warmth of the past few days. Therefore, confidence is not high due to borderline temperatures and onshore flow. Little, if any ice accumulation is expected (would be mainly for elevated surfaces if it were to occur). High pressure slides off the New England coast Saturday aftn as the frontal boundary stalls over the Southeast. The result will be ongoing northeast flow and wedge conditions. Maintained 60-80% POPS across the north and northeast half of the local area Saturday morning/early aftn tapering to low end chance across the southwest. Increased POPs for the Maryland Eastern Shore to categorical Saturday afternoon as a shortwave approaches from the west. Temperatures and low level thicknesses warm through the afternoon, with the p-type becoming all rain across the entire forecast area. Overall, forcing and moisture will be limited, resulting in only light QPF amounts (a tenth to a quarter of an inch north to a few hundredths south). Continue to undercut guidance due to cloud cover and northeast winds. Highs in the mid-upper 30`s north to low 40`s south.
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&& .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
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Low pressure develops offshore the Mid- Atlantic coast Saturday night as shortwave energy digs over the Delmarva. Will linger 40-60% POPS along the coast Saturday evening as the moisture plume begins to push offshore and southward. Lows in the low 30`s north to upper 30`s south. Latest guidance has backed off on precip chances Sunday as the plume of moisture pushes south of the region. BUFR soundings indicate drying in the mid levels, but low level moisture will keep cloudy conditions in place through the day. A few breaks in the clouds expected across the northeast late Sunday. Will keep mention of slight chance to low end chance POPs for the Piedmont, but silent elsewhere. Highs in the low 40`s north to the upper 40s S. Lows in the 30s to around 40 F Sun night and mainly cloudy (except across the ern shore). By Mon, deep cutoff upper low begins to eject NE from west Texas to the southern central Plains as it become engulfed by the northern stream energy. Sfc low pressure moving from the southern Plains to the mid-MS valley will help lift a warm front through the region by late in the day. Still expecting mostly cloudy and cool conditions locally, with highs mainly in the 40s along with a 20-30% POP for light rain.
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&& .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... Frontal boundary remains south of the fa Sun night before lifting north as a warm front Mon. Will continue to carry low end pops for light rain/drizzle in cool wedged airmass Sunday night into Monday morning. Could see some light freezing rain/drizzle across the lower Maryland eastern shore early Monday morning as temps drop to near 32. Otw, just liquid expected as reading stay above freezing but remain in the 30s. Highs Mon from the mid 40s N to lwr 50s S. The warm front lifts north of the region Mon night as strong low pressure tracks from the midwest (where an ice storm is expected) NE into the upr Gt Lakes region by mid week. This slow movement keeps AKQ fa in warm sector for most of next week thanks to high pressure off the sern coast. Models differ on timing of the trailing cold front across the area (GFS faster) but are coming together for a rather strong fropa with a possible triple point low tracking just north of the area late Thurs/Thurs night. Pcpn becomes more scattered and showery in nature due to being in the warm sector. Kept thunder out of forecast with the late week fropa for now. Highs Tues lwr 50s ern shore to lwr 60s SW. Lows Tue night in the 40s. Highs Wed from the mid 50s to lwr 60s south. Lows Wed night mid 40s to mid 50s. Highs Thurs mid 50s to mid 60s. && .AVIATION /20Z FRIDAY THROUGH WEDNESDAY/... VFR conditions prevail across the region this afternoon as a cold front along the VA/NC border moves farther south and offshore. An arctic high will move across the Great Lakes while pushing colder air down into the Mid Atlantic region. Some overrunning warm air will move over the sfc cold air late tonight and Saturday morning and possibly bring some wintry mix to portions of the Md Eastern Shore and areas from Northern VA northward. SBY should be the only CWA TAF site affected. However some light rain may affect Ric/Orf/Phf from the early morning hours to early noon. Expect that cloud ceilings may lower to around 2500-3500 ft during that period with vsbys likely to stay 3 mi or better. The cold air will linger in place into early Sunday and some light rain/drizzle will be possible into Sunday morning. Expect ceilings to be MVFR to low end VFR during that time. Conditions will gradually improve Mon as the cold air erodes and southerly flow begins. Some clouds will linger but expect VFR conditions into Tue. && .MARINE... SCAs for ocean/Ches Bay/sound and Lower James River today...ending various times tonight/Sat morning. SW-W winds to start today...swinging to NNE after backdoor cold front drops S across the waters (through this morning). Speeds to pick up to 15 to 25 kt over the waters after the wind shift (to the N). Sfc hi pres builds into New England for the weekend...keeping persistent NNE winds...though speeds expected to be a few/several KT lower. There is potential for a another (short) period of increased speeds w/ a secondary push of low level CAA Sun morning. && .EQUIPMENT...
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KORF ASOS has returned to normal operation.
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&& .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...Small Craft Advisory until 11 AM EST Saturday for ANZ634-654- 656-658. Small Craft Advisory until 4 AM EST Saturday for ANZ632. Small Craft Advisory until 6 AM EST Saturday for ANZ633-650- 652. Small Craft Advisory until 10 PM EST this evening for ANZ630- 631. Small Craft Advisory until midnight EST tonight for ANZ638. && $$ SYNOPSIS...LKB NEAR TERM...LKB SHORT TERM...LKB/SAM LONG TERM...MPR AVIATION...LKB/JEF MARINE...ALB/TMG EQUIPMENT...AKQ

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