Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 222007 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 407 PM EDT FRI JUL 22 2016 .SYNOPSIS... An upper level ridge prevails over the Mid-Atlantic this weekend through Monday. A weak front clips the area Saturday night and lifts back to the north Sunday. A weak cold front drops into the region Tuesday. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... Current water vapor imagery depicts a trough over the Northeast US with a broad ridge from the central US through the Southeast States. At the surface, the pressure pattern is rather weak, but generally characterized by high pressure across the Southeast with low pressure over Southeast Canada. Temperatures have warmed into the upper 80s to low 90s this afternoon with sct afternoon cu. Dewpoints remain in the low/mid 70s east of I-95, with areas over the Piedmont only now (as of 20z) mixing down into the upper 60s. Heat indices average in the mid/upper 90s with a few locations around 100. Sct convection over the mountains should dissipate before reaching the local area later this afternoon and evening due to limited forcing and a lack of deep moisture. A weak trough slides across the area overnight but this should only bring passing mid-level clouds. Otherwise, expect warm and humid conditions with lows in the low to mid 70s. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/... The upper ridge dampens as it build ewd through the weekend. 850mb temperatures remain in the 20-22C range (+2 st dev). The airmass continues to warm Saturday resulting in highs solidly in the mid 90s inland. Based on todays trends it may be difficult for dewpoints to mix down and are expected to average in the 70-72 range during peak heating Saturday afternoon. This results in heat indices of 100-104 (below the 105 advisory criteria) across the area, and will be highest (around 104) across se VA and ne NC. A weak frontal boundary clips the nrn Mid-Atlantic Saturday night. A 30-40% PoP is forecast for the Ern Shore, with a 20% PoP over the Nrn Neck given some elevated instability and the presence of a shortwave trough within a NW flow regime. Humid Saturday night with lows in the mid to potentially upper 70s. The thermal boundary lifts back to the north Sunday. However, some semblance of a surface trough lingers over central/se VA/ne NC Sunday. This will result in highs in the low 90s Sunday over the Ern Shore. However, higher dewpoints should pool along the old boundary and highs remain in the mid 90s from inland VA to NE NC. This results in forecast heat indices in the 100-104 range over interior s-central VA 105-108 values possible over se VA/ne NC. A few tstms are possible in vicinity of the trough, or along a sea/bay breeze. However, coverage will be rather limited. Continued warm and humid Sunday night with lows in the mid/upper 70s. Hot again Monday with highs in the mid 90s. At this time dewpoints are forecast to remain in the low/mid 70s during peak heating and this could push heat indices into the 105 to 108 range across much of the region. There is a minimal chc of late afternoon tstms over the nw Piedmont counties. Otherwise, dry conditions are expected. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
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A cold front crosses the region on Tuesday and then stalls over the area during the rest of the week...fluctuating/wobbling its position over time in persistent zonal flow aloft. Temperatures still expected to peak in the low-mid 90s for highs with dewpoints in the low-mid 70s. This will generally maintain heat index values of 100-104 degrees each afternoon. Lows generally in the mid 70s each night. Precip chances finally increase to a decent 30-40% POP each afternoon...beginning with the frontal passage on Tuesday afternoon/evening. Thunderstorms should be expected each day. Main impacts will be strong wind gusts and locally heavy rainfall due to pwats upwards of 2.00 inches.
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&& .AVIATION /20Z FRIDAY THROUGH WEDNESDAY/... Surface high pressure has become centered well offshore over the western Atlantic. VFR/dry conditions to prevail through Saturday with mainly S/SW winds around 10 KT. Except will be during the 21Z through 06Z time frame, when an increase in S/SW winds is expected at KORF/KPHF/KSBY, with gusts perhaps reaching 20kt at KORF. Increased mixing should prevent any fog development again tonight. Isolated/scattered tstms possible Sat night at SBY, and then across southern VA and northeast NC Sun afternoon and evening. A cold front approaches on Monday and crosses the area on Tuesday bringing scattered showers and tstms both days...primarily during the afternoon/evening hours. Brief reductions in VSBYS and CIGS to MVFR/IFR levels with the storms. && .MARINE...
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South to southwest winds prevail today through Saturday. Speeds will ramp up to 15-20kt this evening over much of the bay and coastal waters...with gusts to around 25 kt occurring between midnight tonight and 400 AM Saturday morning. Waves/seas will build to 2-3ft and 3-4ft respectively. Middle sections of the Bay may see up to 4ft waves during peak wind gusts overnight. Meanwhile, seas should also build to 4-5ft during this same timeframe from Cape Charles Light to Fenwick Island. SCA flags will be in effect for the Bay beginning at 600 PM this evening through 600 AM Saturday morning...and for all coastal waters from midnight tonight through 400 AM Saturday morning. Winds, waves, and seas all diminish around sunrise Saturday morning. Speeds will be aob 15kt and waves/seas will average 1-2ft and 2-3ft respectively. A surface trough/boundary drops into the area on Saturday, which then washes out/dissipates on Sunday. Winds turn to a more onshore direction by Sunday afternoon with the seabreeze and speeds average aob 10kt. Another front approaches from the northwest early next week with winds becoming more southerly and slightly stronger with speeds aob 15kt.
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&& .CLIMATE... While its certainly going to be hot Sat-Mon, climatologically this is the hottest time of the year with several heat waves having occurred in the past that have been far more intense than what we will experience. Record highs are unlikely to be set and in most cases, doubt they will even challenged within 5 degrees. * RECORD HIGHS: * Sat (7/23) Sun (7/24) Mon (7/25) * RIC: 103 (1952) 105 (2010) 105 (2010) * ORF: 103 (2011) 105 (2010) 105 (2010) * SBY: 103 (2011) 101 (2010) 100 (2010) * ECG: 104 (1952) 97 (2012) 99 (1949) && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...Small Craft Advisory until 6 AM EDT Saturday for ANZ630>632- 634. Small Craft Advisory from midnight tonight to 4 AM EDT Saturday for ANZ650-652-654-656-658. && $$ SYNOPSIS...AJZ/SAM NEAR TERM...AJZ SHORT TERM...AJZ/SAM LONG TERM...BMD AVIATION...LKB/WRS MARINE...BMD CLIMATE... is the U.S. government's official web portal to all federal, state and local government web resources and services.