Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wakefield Virginia
209 am EDT Wednesday Aug 5 2015
a cold front crosses the area overnight as low pressure moves off
the middle Atlantic coast. The front stalls across North Carolina
Wednesday and Wednesday night as high pressure moves east across
Pennsylvania. The front lifts back north as a warm front Thursday
with low pressure moving east along it Thursday night and Friday.
Near term /until 6 am this morning/...
cold front will be entering northwest counties in forecast area in the next few
hours...then continue to the southeast through rest of the night. Convection has
been mainly confined to north-northeast portions of forecast area this. Will keep 20-40%
toward the CST (esp on the eastern shore)...otherwise sky clear-partly cloudy
Meanwhile...low pressure will be skirting the North Carolina beaches
overnight. Precipitation from that system expected to remain S of forecast area. Low temperatures 60s northwest
counties to m70s along the CST.
Short term /6 am this morning through Friday/...
surface high to the north will build south across the forecast area Wednesday. Models now
push best moisture and sprt for any precipitation south into NC keeping most if
the forecast area dry drng the daylight hours. Kept slght chance xtreme southwestern counties
around 21z or so. Pt to mostly sunny and less humid as deep temperatures drop.
Highs l-m90s xct M-80s along the coast. Heat index values remain
Frontal boundary begins to move back north as a warm front Wednesday night but
still prognosticated across NC at 12z Thursday. Some warm air advection at 850 mb noted to produce
slght chance probability of precipitation across southern most counties aftr midnight. Otw...pt cloudy
with lows m60s north to l-m70s south.
Warm front lifts north into the akq forecast area Thursday but how far??? the exact
location (best guess is across southern Virginia attm) will likely determine the
pop/tmp and thunder forecast as low prs apprchs from the west enhancing
the moisture fields drng the aftrn/night. Probability of precipitation ramp up to high chance drng
the afternoon and likely at night. Highs 85-90 before the rain moves
in. Lows Thursday night u60s-l70s.
Models differing on Friday with respect to how fast the systm exits off the coast.
Splitting the difference keeps likely probability of precipitation across the area drng the
morning tapering off to chance probability of precipitation drng the afternoon. A rare Summer wedge
possible Friday across the northwest Piedmont where temperatures will be hard pressed to
get much above 80. Otw...highs in the 80s. A widespread rainfall appears
likely with qpf's around one inch...higher along the coast.
Long term /Friday night through Tuesday/...
long term period starts off Friday night with a middle-level shortwave
trough and associated surface low pressure pulling offshore. Will hold on to
some lingering probability of precipitation Friday night with decreasing cloudiness and low
temperatures in the middle 60s to lower 70s. Weekend then shaping up to be dry
and comfortable with surface hi pressure building into the area. Expect a
prtly cloudy sky with fairly low humidity and hi temperatures only in the low
to middle 80s both days. Next chance of rain comes Monday and Tuesday as more
upper-level energy approaches from the west. Will cap probability of precipitation at 30% at this time with
this being several days out.
Aviation /06z Wednesday through Sunday/...
Cold front has settled just north of the local area this morning.
Showers/thunderstorms currently impacting ksby will push east of
the site by the 05/06z taf issuance. Another isolated shower
impacted kphf...but has since moved out over the Bay. Expect the
remainder of the overnight to be dry...outside of an isolated
shower near the coast. Otherwise...southwesterly surface winds generally at or below 10
knots with broken high clouds at or above 25k feet above ground level.
For today...cold front slowly drops across the region
today. Little more than a wind shift to the northwest late today and scattered
afternoon cumulus expected with the frontal passage. Dry forecast will
More unsettled conditions arrive later Thursday into Friday as
low pressure and its associated cold front affect the area. High
pressure builds in from the north Saturday and Sunday.
marine forecast updated with the Small Craft Advisory over northern coastal waters extended to
4 am Wednesday and a new Small Craft Advisory added over the Bay until 1 am. The Small Craft Advisory over
the Bay will be marginal but winds are expected to increase to 15-20
knots ahead of an approaching cold front tonight. Winds then decrease aftr
midnite as the front nears the waters and drops into the region into the
morng hours. Some strong wind gusts are also possible with any convection
this aftn/eveng. Northwest flow then follows for Wednesday afternoon...with
winds/waves/seas decreasing. North winds at or below 10 knots Wednesday night become Ely
Thursday with surface hi pressure building northwest of the area. A complex area of low
pressure then approaches from the west Thursday night and Friday...with Small Craft Advisory conds
possible depending on the exact track of the low which is uncertain
at this time.