Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wakefield Virginia
732 PM EDT Friday Jul 11 2014
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
Near term /until 6 am Saturday morning/...
***nws survey team confirms both an EF-0 tornado and straight line
winds in Virginia beach*** (see pnsakq for details)
***nws confirms straight line wind damage in the Capron area and
across Southampton county***
Latest analysis showing the surface front/trough becoming washed out
off the NC coast. Aloft...WV satellite reveals sheared out shortwave
pushing east of the mountains but with only a few very isolated showers
across the local thus far. Will maintain a 20% pop through sunset
most areas...then becoming mostly clear. Light flow overnight and
mainly clear skies will promote some patchy fog development inland as
dew points remain in the 60s so have this into the grids after 06z.
Lows in lower to middle 60s inland to 65-70 f near the coast.
Short term /6 am Saturday morning through Monday/...
overall looking like a nice weekend as frontal boundary will
dissipate over the Carolinas with high pressure building into the
region. Still some weak instability over NE NC and with light flow
could see a seabreeze induced isolated storm in the afternoon so will 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 Lower-Middle 80s at the
coast to upper 80s/around 90f along/west of the I-95 corridor. Mainly
dry Sat night with lows in the 60s to around 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.
However...rising heights aloft looks to cap the atmosphere for the
most part so will only carry 20-30% positive at most for afternoon thunderstorms well
inalnd and over the north...keeping it dry across southeast Virginia/NE NC. Highs
u80s-l90s except m80s at the beaches.
Flow turns to the south-southwest in earnest on Monday...with increasing moisture
and heat returning. Enough instability prognosticated for scattered afternoon thunderstorms
all areas except NC Outer Banks where a 20% pop will be
maintained. Highs 90-95 f.
Long term /Monday night through Friday/...
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. Highs Tuesday expected in the low 90s with dew points in
the near 70. 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 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. Strong to severe thunderstorms also possible
as models depict marginal shear and MLCAPE > 2000 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.. but...with the
stalled boundary across the southeast and a passing shortwave
trough...showers and thunderstorms may be possible next weekend.
Aviation /00z Saturday through Wednesday/...
VFR conditions prevail at all terminals this evening. VFR will
prevail on Saturday as well...as high pressure dominates the
weather over the region. The challenge with the 00z tafs is the
extent of any fog overnight...given weak moist onshore flow...and
mostly clear skies. Guidance is most bullish for IFR conditions at
ksby and kphf...and have followed closely. MVFR expected at
kric/kecg...and both terminals could briefly see IFR conditions
overnight. It appears that enough low level flow will persist at korf
to prevent significant fog formation...and have maintained VFR
conditions throughout the period.
Dry weather continues into sun with the high offshore and low
pressure tracking well northwest of the local area. Next front could
bring the potential for more showers/thunderstorms to the region Monday and
10kt NE/east winds today as a stationary boundary has sagged south
of the akq marine waters. Meanwhile...broad area of high pressure
builds over New England...sliding off the coast by Saturday
morning. Flow returns to the south late Sat night and
sun...increasing slightly to 10-15 knots gusting to 18-20 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 5-6 feet across the northern
waters by Monday night. High pressure builds in Post front briefly
turning winds to the NE. The winds become light and variable as the
high builds east and an area of low pressure forms along the
stalled frontal boundary across the southeast.