Area Forecast Discussion
Issued by NWS Wakefield, VA

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619 FXUS61 KAKQ 280759 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 359 AM EDT TUE JUN 28 2016 .SYNOPSIS... A cold front approaches from the west today, as a pre-frontal trough remains over the local area. The front will slowly move across the region late this afternoon through tonight. Weak high pressure builds in from the north Wednesday and Thursday as the front stalls across the Carolinas. The next cold front approaches the region late in the work week. && .NEAR TERM /THROUGH TONIGHT/... Current analysis depicts low pressure over eastern Canada, with a surface cold front extending SW through western NY and into the Ohio Valley. A pre-frontal sfc trough is in place along/just E of The Appalachians. Ongoing widespread shower with embedded tstm activity over the Ches Bay and eastern Shore, with coverage more isolated to widely scattered across central and south central VA (with dry conditions over far se VA and ne NC). GFS/NAM reveal that although CAPE is very limited, elevated instability per negative showalter indices over much of the area has been sufficient when combined with decent lift to keep showers going along with a few tstms. Activity off to the W/SW of metro richmond likely to increase in coverage over the next few hrs and will carry likely POPS of 60-70% from the eastern shore back W/SW through cent ral and south central VA through the morning, tapered to only low chc POPS over the far SE through mid morning. However, expect highest coverage of precip to gradually shift E/SE through the late morning/early aftn hrs, with likely POPS overspreading se VA and ne NC by late morning through much of the aftn. Meanwhile, some breaks in the clouds are expected over central VA as POPS decrease somewhat by mid aftn onward. If enough clearing occurs this aftn, could see some marginally strong tstms develop, mainly W of ches Bay and SPC has this approximate area in a marginal risk for severe tstms. Still, greater effective shear of 30 Kt+ should stay N of the entire area closer to stronger h5 height falls since the upper low will be well to our north across Ontario. Given the continued moist airmass with precipitable waters around 2.00" and relatively weak steering flow aloft (at least through 18Z) locally heavy rain will be the main concern and will address in the HWO. Highs generally in the low-mid 80s today (possibly staying in upper 70s/around 80 depending on rain coverage through the aftn). Upper low tracks from NY state to New England later tonight, a slightly slower secenario compared to past model runs. Still expect the cold front to push through the local area, though the front may hang up near the coast. Height falls will result in cyclogenesis just off the Northeast coast Tuesday night. As the low wraps up, lingering mid level moisture across the northeast forecast area in concert with strengthening forcing for ascent is expected to produce scattered showers Tuesday evening. Best chances will be from the Northern Neck to the Eastern Shore. Drying late Tuesday night with a clearing sky inland. Partly- mostly cloudy near the coast. Lows range from the mid to upper 60`s. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY/... Broad, upper level trough pushes across the region Wednesday. The frontal boundary expected to stall in the vicinity of northeast North Carolina as high pressure builds in from the northwest. Departing 70+ knot upper jet and enough lingering mid level moisture (precipitable waters drop below 1.5 inches) should be enough for widely scattered diurnally driven showers and thunderstorms, mainly over far southern VA and ne NC. Highs generally in the mid 80`s under a partly cloudy sky. Best chances for measurable precipitation will be south of the Albemarle Sound Wednesday night, but will keep mention of slight chance showers. Lows generally in the low to mid 60`s N to upper 60s S. Surface high pressure centers along the Mid-Atlantic coast Thursday morning as the next upper level shortwave approaches from the west. Low pressure progged to develop over the Southeast states with an inverted trough extending northward over the central Appalachians. Upslope flow and the approaching wave will result in showers and thunderstorms over the higher terrain. GFS is wettest model and would support high chc POPS into the CWA while the NAm/GEM are drier. Expect much of the forecast area to remain dry, but will mention a 20-30% POP for showers coming off the higher terrain Thursday afternoon into areas W of the Bay. Otherwise, near seasonal temps again with highs forecast in the mid 80`s. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... Active northern stream upper trough will remain the dominant wx feature through the medium range period. Resultant W-NW flow will continue for the late week/Holiday weekend period. Meanwhile, at the surface, a rather stagnant pattern looks to set up with weak front/sfc trough dropping into the area and lingering over the local area. Warm, moist airmass (PW AOA 2" from Friday night through the weekend) in tandem with the boundary and numerous disturbances riding across the area in WNW flow aloft will bring a solid chance for mainly diurnally driven showers and tstms. Have continued solid chance pops each day during this period. Stronger front crosses the area by later Sunday into Monday. For temps, pattern favors temperatures hovering right around climo normal...with highs in the mid to upper 80s. Early morning lows generally in the 60s. && .AVIATION /08Z TUESDAY THROUGH SATURDAY/... Early this morning, a cold front was dropping thru the Ohio valley. The front will move southeast and pass acrs the Mid Atlc States tonight into Wed morning. An upper level disturbance and surface trough will produce sctd showers and tstms today into this evening, with additional sctd pcpn possible with the front tonight. Conditions are expected to generally be MVFR with the weather, but a few hours of IFR will be possible at RIC and SBY. Winds will be light and generally fm the south. OUTLOOK...Expect mainly dry/VFR conditions for Wed and Thu, as high pres nudges in fm the WNW. More chances for pcpn return next weekend. && .MARINE... Latest obs reflect sub-sca E-SE flow across the waters this aftn. 1024+mb sfc High remains centered off the New England and northern Mid-Atlantic coast, while a cold front continues to slowly slide across the Ohio valley. Sfc high will continue to slowly drift east through tonight as a pre- frontal trough approaches from the WNW. As noted in the near term above, near-term CAMS becoming a bit less bullish on convection...and are anticipating a bit more in the way of clearing/cooling over the area later tonight. This, in tandem with tightening pressure gradient w/pre-frontal trough building in will likely result in at least a few hours of low end SCA winds in the Ches Bay, and have accordingly hoisted SCA for tonight. Winds will lessen a bit and become SSW as the high moves farther offshore and the trough moves in Tuesday morning. SSW flow 10 to 15 kt continues Tue into Tue ngt, as the (weak) cool front approaches from the WNW. The front and accompanying wind shift to the N-NE wind drops through the waters Wed morning into Wed aftn with high pressure pushing into the Great Lakes and OH Valley. This will maintain a NE to E flow later Wed and Thu. Weak front/sfc trough will meander over/just south of the area for the late week period, and will serve as the focus for late day convection over the area late in the week and through the weekend. && .CLIMATE... Chances to add to an already wet month mainly tonight and Tue. June has been another wet month at Richmond, the monthly total rainfall through the 24th stands at 6.92" and already makes this the 9th wettest June on record (2004 is wettest June with 9.93"). && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...None. && $$ SYNOPSIS...LKB NEAR TERM...LKB SHORT TERM...LKB/SAM LONG TERM...MAM AVIATION...TMG MARINE...MAM/TMG CLIMATE...

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