Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 010042 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 842 PM EDT Sun Apr 30 2017 .SYNOPSIS... Bermuda high pressure prevails off the Southeast Coast tonight into midday Monday. A cold front approaches from the west Monday afternoon, and pushes across the region Monday night, with high pressure returning Tuesday and Wednesday. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
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Quick update to account for some sct showers pushing across the I-85 corridor in the SW CWA. These showers should quickly diminish in areal coverage through 02z/10pm...with an otherwise quiet, dry night ahead. Potential for some developing low stratus once again towards morning, especially along the coastal plain. Otherwise, partly to mostly clear and mild with early morning lows 65-70. previous valid discussion...issued 4pm EDT The ridge aloft over the sub- tropical wrn Atlantic will continue to prevail tonight as a cold front over the Mississippi Valley pushes ewd tonight. Surface high pressure will remain anchored off the Southeast coast, with a quasi-stationary boundary over the Delmarva lifting N as a warm front. Temperatures this afternoon are generally in the low/mid 80s across the region. These values will slowly fall into the 70s this evening, with overnight lows in the mid/upper 60s. Mostly clear this evening, with some patchy stratus developing late tonight.
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&& .SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/... The cold front approaches from the W Monday aftn as the Central Plains trough lifts into the Great Lakes. The front is expected to slow as it pushes across the Appalachians with strong surface heating to the lee of the mountains. Therefore, PoPs should be slow to increase through the aftn, and mainly over the Piedmont initially. The ridge will hold strong along the coast with the ern half of the area remaining dry through much of the day Monday. 500mb flow ahead of the trough reaches 70-80kt, which yields 0-6km bulk shear ~50kt. However, mid-level lapse rates (850-600mb) are rather poor, but much steeper around 500mb, and the net result is 0-1km MLCAPE values of 500-1000 J/kg once the strongest synoptic forcing arrives locally (mainly 21-03z). The SPC Day 2 marginal risk has been expanded ewd to the interior coastal plain, with a slight risk introduced for the piedmont. PW values ~1.5in combined with strong forcing could result is some locally moderate to heavy rain. The cold front crosses the region Monday night and pushes offshore by 12z Tuesday. PoPs taper off from NW-SE from 06-12z as drier air arrives from the NW. Highs Monday will generally be 80-85F W, with mid/upper 80s farther E (upper 70s for the Atlantic coast of the Ern Shore. Lows Monday night range from the upper 50s W to the low/mid 60s along the coast. A south to southwest wind will become breezy by mid morning as the sfc pressure gradient responds to the approaching strong cold front. Gusts around 25-30 mph should be common by late morning...increasing to sustained winds of 20-25 mph with gusts averaging 30-35 mph. Model cross sections of lapse rates (and essentially the mixing layer) are supportive of these speeds, which are higher than model guidance. A trough aloft builds over the Ern Conus Tuesday and dampens to a more zonal flow pattern by Wednesday. Surface high pressure builds across the Southeast States Tuesday, then dissipates Wednesday as a dry cold front approaches from the N. Temperatures will be lower Tuesday, but still on the warm-side of normal with highs ranging from the mid 70s to near 80 under a mostly sunny sky. Mostly clear Tuesday night with lows ranging through the 50s. Mostly sunny Wednesday with highs in the mid/upper 70s, and locally upper 60s/low 70s for the Atlantic coast of the Ern Shore. Remaining breezy Monday night into Tuesday due to cold air advection and a continued tightened sfc pressure gradient behind the cold frontal passage. The wind becomes westerly with speeds averaging 15 mph with gusts around 25 mph inland and 20 mph with gusts around 30 mph...mainly after midnight Monday night. For Tuesday, a WSW wind will average 20 mph with gusts of 25-30 mph areawide. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... Sfc high pressure north of the area slides closer to the NJ shore Wednesday night and east of the New England coast on Thursday as a warm front lifts north into the region. Meanwhile, sfc low pressure develops over the TN/OH Valleys into Friday. SE/onshore winds become breezy at the coast Thursday into Thursday night...becoming more S on Friday after the warm front lifts well north of the area. Decent amount of uncertainty of how/where the sfc low will develop and where it will track Friday through Saturday night (including when its associated cold front will cross the region). Kept the forecast fairly general/broad-brushed during this time. Weak cold air advection behind the low may be reinforced by another colder shot of Canadian, but again, there is a lot of uncertainty at this point. Overall, a brief warming trend can be anticipated for Thu night/Fri with a gradual cool down with highs below normal and lows near normal. && .AVIATION /01Z MONDAY THROUGH FRIDAY/... A quasi-stationary frontal boundary, currently located just to the north of Salisbury, will continue to lift north of the area overnight tonight. A cold front will approach the region late in the day on Monday. Mainly clear skies are expected to continue through the first- half of the night. Similar to the past couple of nights, MVFR stratus may develop at all TAF sites generally after 08Z. Visibility restrictions are not anticipated as winds continue to increase through the overnight hours, limiting any fog potential. Conditions return to VFR mainly after 14Z Monday. Windy conditions are anticipated for Monday with southwest winds sustained around 15-20 knots and gusts in excess of 30 knots possible. Outlook: The cold front approaches from the west late in the day and passes across the region overnight. This will bring the potential for showers and thunderstorms from late afternoon/early evening for RIC and then shifting to the coast during the evening through the early overnight hours. Any showers/thunderstorms have the potential to produce sub-VFR conditions along with locally strong wind gusts. High pressure returns Tuesday and Wednesday and slides offshore Thursday as low pressure approaches from the west. This low pressure system potentially impacts the region Thursday night and into Friday. && .MARINE... Winds generally SW 10-15kt through tonight...increasing initially with typically diurnal push around sunrise and continuing to increase through Monday as a strong cold front approaches the region. Low-end SCA conditions to begin for the Bay around sunrise Monday morning with the normal diurnal push. Currituck Sound and Ern VA rivers to experience low-end SCA winds by mid morning...then winds/seas/waves increase all waters in the afternoon as the sfc pressure gradient really tightens up in response to the front as it nears the mountains. S-SW winds will average 15-25kt with gusts of 25-30kt primarily Mon aftn into Mon evening before the frontal passage. A brief period of gale force gusts around 35 kt will be possible (especially over the coastal waters) during the frontal passage late Mon evening into the overnight hours. Cancelled gale watch since any gale gusts will be related to convection/front (rather than synoptically-driven) and can be handled with Special Marine Warnings as needed. SCA flags hoisted for all waters with beginning and end times adjusted. See WBCAKQMWW for more details. Seas build to 4-6ft Mon aftn and increase to 5-8ft north/4-6ft south Mon night. Waves on Ches Bay build to 4ft by late Mon morning/early aftn with up to 5ft possible in the middle of Ches Bay Mon evening. Winds become WSW behind the front after midnight Mon night and then turn more SW on Tue. Wind speeds slowly diminish within this timeframe...averaging 15-20kt by mid morning Tue. Waves on Ches Bay anticipated to be 2-3ft by sunrise Tue. Seas will be slower to subside below 5ft until mid morning Tue for srn coastal waters and not until Tue evening for nrn coastal waters. SCA flags incrementally drop off from south to north as Tue progresses. Again, please see WBCAKQMWW for further details. Fairly benign conditions anticipated for Wed/Wed night with high pressure over the area. Variable aob 10kt Wed/N-NE aob 15kt Wed night. A warm front is expected to lift north across the waters Thursday as low pressure develops over the TN/OH Valleys into Friday. SE/onshore winds become breezy with speeds averaging 15-20kt Thu aftn at least through Fri aftn. Seas anticipated to build to 4-6ft and persist into Sat morning before subsiding. SCA conditions should be expected during this time. && .HYDROLOGY...
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Flood advisory continues in Mecklenburg County, VA. VDOT still reporting numerous roads closed in the Kerr Dam area, creating ongoing navigation concerns.
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&& .CLIMATE...
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Richmond and Norfolk will each establish new records for the warmest April on record. Barring any unexpected changes, both sites will establish new records by greater than 1 degree. The following is with data as of the 29th. Unofficial final monthly data will be added tomorrow. April 2017 Avg temp Record Location to date Avg temp Year -------- ---- ---- ---- Richmond 63.7 63.1 1994 Norfolk 66.0 65.3 1994 **** All 4 climate sites broke record high minimum temps for 4/28...4/29 and for the month of April. Barring any unlikely quick temperature drops, another round of record high minimums will be established at climate sites for 4/30. A record maximum was tied today at Salisbury. See PNSAKQ for details. Record high temps for today 4/30 (Actual): RIC...93 in 1974 (86) ORF...93 in 1888 (89) SBY...86 in 1974 (86, Record tied) ECG...90 in 1974 (86) Record high minimums for today 4/30: RIC...63 in 2014 ORF...67 in 1994 SBY...63 in 1983 ECG...65 in 2014
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&& .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...Small Craft Advisory from 10 AM Monday to 10 AM EDT Tuesday for ANZ635-636-638. Small Craft Advisory from 10 AM Monday to 8 AM EDT Tuesday for ANZ633-637. Small Craft Advisory from 4 AM Monday to 6 PM EDT Tuesday for ANZ630>632-634. Small Craft Advisory from 2 PM Monday to 4 PM EDT Tuesday for ANZ654. Small Craft Advisory from 2 PM Monday to 10 AM EDT Tuesday for ANZ656-658. Small Craft Advisory from 2 PM Monday to 11 PM EDT Tuesday for ANZ650-652. && $$ SYNOPSIS...AJZ NEAR TERM...AJZ/MAM SHORT TERM...AJZ/BMD LONG TERM...BMD AVIATION...AJB/AJZ MARINE...BMD HYDROLOGY... CLIMATE...

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