Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wakefield Virginia
351 am EDT Wednesday Jul 30 2014
high pressure drifts across the middle Atlantic region today...then
slides off the coast tonight into Thursday. A frontal boundary
will develop along the coast by Friday...then move inland
through the weekend.
Near term /until 6 PM this evening/...
very comfy air over the forecast area at this time. Broken-overcast clouds (cigs mainly 6-8kft)
across portions of central/scntrl Virginia holding up temperatures a bit...otherwise
most temperatures (away from the immediate cst) from the m50s to m60s.
Been watching area of rain showers tracking through portions of scntrl Virginia
while slowly dwindling (past couple hrs). Will hang onto slight chance
probability of precipitation near the Virginia/NC border on into interior NE NC through the early
morning hours. Broad/unseasonably amplified trough remains over the eastern
Continental U.S....continuing to provide mainly dry/comfy weather for the forecast area today. Expecting
p/msny conds...W/ dewpoints remaining from the 50s to l60s...and hi temperatures
avgg 5 to 10 degrees f (once agn)...ranging from the u70s along the
immediate CST to l/m80s inland.
Short term /6 PM this evening through Friday/...
another comfy night tonight west/ clear to pcldy conds. Most low temperatures
ranging from the u50s to m60s. Trough aloft weakens/shifts a bit
westward Thursday into Friday. Weak surface hi pressure will be off the CST Thursday...with
south-southeast low level flow across the area. Only a very slight increase in
humidity is expected...otherwise partly to mostly sunny with high
temperatures in the M/u80s. By Friday...Bermuda high pressure begins to
rebound across the western Atlantic...W/ deep layered southwesterly flow aloft
(ovr the eastern seaboard) and a surface frontal boundary developing
along the Virginia/NC coast. The combination of these features will
result in incrsd rain showers/thunderstorm chances locally (especially aftn)...and
thus will carry solid chance probability of precipitation (30-40%) Friday. With plenty of clouds
around and precipitation possible...hi temperatures Friday will likely be a touch
cooler than Thursday...in the l/m80s.
Long term /Friday night through Tuesday/...
forecast rationale remains largely the same for medium range period.
Persistent upper level trough over the eastern third of the Continental U.S.
Will retrograde back west into the MS valley ahead of the building
western Atlantic ridge. This will allow for precipitable water values/deep layer
moisture ramping up through the period. Thus, scattered rain showers expected
through the period ahead of the advancing coastal front/inverted
trough, which will locate along/just off the mid-Atlantic/southeast
coast Saturday, eventually moving inland across the coastal plain by
Monday. Given that there is no significant forcing mechanism to key
in on, will lean towards climatology and use diurnally driven probability of precipitation
through the Sat-Tuesday time period. For temps, look for highs to remain
at or below climatology normal...generally ranging into the l-M 80s
Sunday/Monday...85 to 90 on Tuesday ahead of an approaching cold
front. Early morning lows in the 60s Sun morning, incrementally
increasing to u60s to around 70 by early Monday/Tuesday.
Aviation /08z Wednesday through Sunday/...
weak area of high pressure will slide over the area Erly this
morning. Middle level wave passing through the middle-Atlantic will be
strong enough to help initiate some very isolated showers across
the area. Expect winds to veer to the S/southeast this afternoon with a
scattered cumulus field developing.
Outlook...dry weather is forecast through Thursday. There will be a
a chance for mainly afternoon/evening thunderstorms Friday. VFR is expected
outside of precipitation through Friday.
Note: observations from ksby are not readily available due to a
communications problem. Return to service is unknown at this time.
However...current information may be obtained by calling into the
ASOS site directly. Amend not schedule will be appended to the ksby taf
until further notice.
weak surface hi pressure over the middle Atlantic today will lead to benign marine
conditions...winds at or below 10 knots and waves/seas at or below 2 feet. The hi slides
offshore tonight...with winds becoming S/southeast ~10 knots. This will continue into
Thursday with seas over northern coastal waters building to 3 feet. A coastal/inverted trough
develops near the middle-Atlantic CST Friday through sun...with sub-Small Craft Advisory
conditions expected through the period. Winds will continue out of the
S on average with rain chances increasing over the waters.