Area Forecast Discussion
Issued by NWS Wakefield, VA

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KAKQ 222002 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 402 PM EDT FRI JUL 22 2016 .SYNOPSIS...
-- Changed Discussion --
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.
-- End Changed Discussion --
&& .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
-- Changed Discussion --
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.
-- End Changed Discussion --
&& .SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/...
-- Changed Discussion --
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.
-- End Changed Discussion --
&& .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... Not as hot acrs the region thru the extended period, with Mon and Tue being the hottest days in advance of a cold front approaching fm the NW. Unstable airmass combined with a lee trough ovr the area on Mon and a cold front pushing into and acrs the region on Tue will result in isolated to sctd showers and tstms. That frontal boundary will then become nearly stationary along the VA/NC border or just S of there ovr NC Wed thru Thu. So, the best chc for showers and tstms will be acrs the srn half of the area during this period. Highs in the lower to mid 90s Mon and Tue, in the upr 80s to lower 90s Wed, and in the mid 80s to lower 90s Thu. Lows will range thru the 70s Sun ngt and Mon ngt, and mainly in the lower to mid 70s Tue ngt and Wed ngt. && .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... S Winds currently avg around 10 KT across most of the area, with a few locations as high as 15 KT. Bay waves will average 1-2 ft with coastal seas 2-3 ft through early this afternoon. The pressure gradient will increase a bit more later today, and especially tonight, so S/SW winds will ramp up and average 15-20 KT during this period over much of the Bay and the coastal waters. With water temps in the 80s and a decent SSW low level Jet strengthening by tonight, should be a favorable enough setup for a southerly overnight SCA event in the Bay. Will be raising SCA headlines there with the 4 am issuance. Expect a few gusts in the rivers to approach 20 KT as well, but should be shorter lived and will allow next shift to evaluate need for a SCA there (as well as in the coastal waters off the VA/MD eastern shore for gusts to 25 KT and seas approaching 5 ft out near the 20 NM offshore areas). Waves over the Bay building to 3 ft, and coastal seas to around 4 ft N and 3 ft S. The sfc trough/boundary drops into the area on Sat with lighter W/SW flow turning back to the S later Sat into Sat evening. The front then washes out/dissipates on Sun, with winds to avg < 10 KT and becoming onshore by afternoon with the seabreeze. Another front approaches from the NW early next week. && .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...
-- Changed Discussion --
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.
-- End Changed Discussion --
&& $$ SYNOPSIS...AJZ/SAM NEAR TERM...AJZ SHORT TERM...AJZ/SAM LONG TERM...TMG AVIATION...LKB/WRS MARINE...LKB CLIMATE...AKQ

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.