Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wakefield Virginia
1105 am EDT Friday Jul 11 2014
a frontal boundary slowly pushes south into North Carolina later
today and tonight. High pressure builds south across the middle
Atlantic region through the weekend. Low pressure moves across
the Great Lakes region with the trailing cold front approaching
from the northwest early next week.
Near term /until 6 PM this evening/...
***nws survey team will survey the damage in Virginia Beach today to
determine the nature of the damage***
***nws confirms straight line wind damage in the Capron area and
across Southampton county***
Latest analysis showing surface trough now generally from just off the southeast
Virginia coast SW though the NC coastal plain. Aloft...WV satellite
reveals shortwave pushing through eastern Tennessee/western NC although this
feature is fairly weak. Airmass fairly stable right now...convection
limited to the Gulf Stream off the NC coast with some low clouds
still in place across most of the local area except for west central
portions of the County Warning Area.
For the afternoon expect just some isolated to widely scattered thunderstorms
over far southern/southeast Virginia and NE NC (pops only 40% at most due to
flow turning onshore). A lot less shear is present than yesterday and
precipitable waters per 12z soundings are generally between 1.0 and 1.5" (compared
to >2.0" on yesterday's 12z wal sounding). Thus...only anticipate
some brief heavy downpours and sub-severe gusty winds if any
convection affects the region this afternoon. Temperatures are warming slowly
thus far in areas with low clouds...but made little adjustment to
highs given a fair amount of afternoon sunshine and eventual deeper
mixing. Highs average in the middle to upper 80s well inland and 80-85 f
near the coast.
Short term /6 PM this evening through Sunday/...
widely scattered evening convection confined to NE NC...otherwise
skies become mostly clear north to partly cloudy S. Lows lower to middle
60s northwest to around 70 f far southeast.
Models continue to show frontal boundary washing out across the
Carolinas Sat with high pressure building into the region. Data showing
just enough instability to keep slight chance diurnal probability of precipitation across interior
NE NC. Otw...pt to mostly sunny and warmer as 850 mb temperatures rise a bit.
Highs 85-90 f. Mainly dry Sat night with lows 65-70 f.
Next short wave prognosticated to move across the Great Lakes and NE states sun
with a surface thermal trough prognosticated east of the mts during the afternoon.
Kept 20 pop for afternoon thunderstorms most areas except southeastern Virginia / NE NC. Highs
u80s-l90s except m80s at the beaches.
Long term /Sunday night through Thursday/...
highly anomalous flow will develop over the Continental U.S. During the medium
range...as a strong closed low drops over the Great Lakes region.
The result will be below normal temperatures and wet conditions from the
upper Midwest to the Ohio Valley. However...the local area remains
seasonably warm as much of the cooler air will be locked west of the
As an anomalous trough develops over the eastern Continental U.S....height falls
and increase winds aloft will result in better forcing for ascent
over the local area. With a warm/moist airmass already in place
(model derived precipitation waters ~ 2+ inches)...expect better coverage
of showers/thunderstorms Monday afternoon along a sharpening
Lee/thermal trough. However...the best dynamics will remain west of
the local area along the cold front...so the best chances will be in
the north and west. Another area of showers/thunderstorms will
likely develop along the trough/boundaries...closest to the best
instability. Still some subsidence/warm air aloft visible in
soundings...so will leave at low end chance. Highs Monday expected in
the low-middle 90s. With dew points in the middle-upper 60s...heat indices
will be near 100 inland. Strong speed maximum rounds the deep closed low
over the Great Lakes Tuesday...ejecting the low northeastward into southeast Canada.
The cold front drops into the region Tuesday-Tuesday night. Strongest
dynamics lift well north of the region with the closed low...but
height falls and perturbations in the west-southwest flow will result in
scattered-numerous showers/thunderstorms. Based on spatial and timing
differences of the front and still being day 6...will cap probability of precipitation at
chance with this package. Strong to severe thunderstorms also
possible as models depict marginal shear and MLCAPE > 2500 j/kg.
Anomalous trough will push the southern portion of the front into the
deep south...but the eastern portion likely stalling over/off the
middle-Atlantic coast as an anomalous upper ridge remains parked over
the western Atlantic. Will maintain slight chance-chance probability of precipitation Wednesday
across the southeast as the front will likely linger over the region. Surface
high pressure will be slow to build into the region in wake of the
front as upper trough remains over the eastern Continental U.S..
Aviation /15z Friday through Tuesday/...
a stationary frontal boundary currently resides from central Maryland
southward into central Virginia. Lingering low-level moisture is producing
some MVFR/IFR conditions at the taf sites this morning. Look for
these conditions to continue into late morning before improving.
What's left the front will sag south into southeast Virginia/NE NC today...where
limited convection will reside. Drier air returns tonight into Sunday.
Next front could bring the potential for more showers/thunderstorms to the
region late Sunday or Monday.
sub-Small Craft Advisory conditions will continue today as a stationary boundary
slowly sags south over the waters. Winds will gradually become light
east-NE behind the front through this afternoon. Meanwhile...high pressure
builds over New England today...sliding off the coast by Saturday
morning. Flow returns to the south late Sat night and
sun...increasing slightly to 10-15 knots. Southerly flow persists through
early next week. A cold front will approach the waters late
Monday...crossing the waters Tuesday-Tuesday night. Persistent southerly flow may
push seas to 5 feet across the northern waters by Monday night.