Scientific Forecaster Discussion
fxus61 kakq 280147
Area forecast discussion
National Weather Service Wakefield Virginia
947 PM EDT Mon Mar 27 2017
a cold front approaches from the west tonight and crosses the
region late Tuesday through Tuesday night. High pressure builds
in from the north on Wednesday. The high retreats to the
northeast on Thursday as the next system approaches from the
Near term /until 6 am Tuesday morning/...
current WV imagery and surface analysis indicate a potent low
over the Ohio Valley, which is triggering widespread convection
swd through the Tennessee Valley. Diurnally driven convection
of the higher terrain of Virginia into nrn Virginia has waned this evening
with the loss of surface heating. Partly to mostly cloudy and
mild locally this evening as high pressure off the coast
prevails, with temperatures as of 9 PM ranging through the 60s
to around 70f, with mid 50s along the immediate Atlantic coast
of the ern shore.
Upper level ridging begins to break down later tonight as the
mid/upper level trough currently centered over southeast
MO/southern Illinois pushes east overnight. After a period of mainly
dry conditions, pops will ramp back up after 04-06z as the front
approaches from the west and mid-upper level heights fall along
with some increase in mid level lapse rates between 06-12z. Low
level instability will be very low, but think there is enough
instability aloft to mention a slight chance for tstms over
roughly the western 1/2 of the County Warning Area after 08z. Will carry ~40%
chc pops west of I-95 to 20% to 30% or less farther east and
southeast. Warm with lows mainly 55-60 f. With the moist
boundary layer, GFS is indicating a fair amount of fog, but
given a south-southwest wind of 5-10 mph and warm temperatures, think this
is overdone and that areas of low clouds are more likely.
Short term /6 am Tuesday morning through Thursday/...
upper level trough pushes into the area Tue, with a model
consensus pushing the main shortwave energy across southern
Virginia/and eastern NC from 18-00z. Have raised pops to likely (60%)
in the aftn over portions of far southern Virginia and northeast NC
where deepest lift and moisture look to coincide during peak
heating hours. Maintained mainly high chance pops (50%)
elsewhere (except for a small area of likely pops across the northwest.
Continued warm W/ highs mainly in the mid to upper 70s (could be
around 80 f if enough sunshine develops). There will be some
potential for a few stronger storms Tue aftn/evening as speed
and directional shear increases and sfc dew pts will be around
60f. Overall not looking like widespread severe wx as there is
still some question as to how much storm organization there will
be as latest models are hinting at a lot of clouds and an
earlier arrival of precip by late morning. Storm Prediction Center has area in
marginal risk for severe wx and this seems about right given the
current parameters depicted in the models. Overall, highest
shear values look to reside over NC.
Will linger the chance pops through the early evening west and to
around midnight along the coast. Drying after midnight with
lows mainly 50-55 f. Becoming partly/mostly sunny Wed after some
early clouds (especially south) as drier air moves in from the
north. Somewhat cooler but still a little above avg with highs
60-65f near the coast and in the upper 60s to lower 70s well
inland. Upper ridge axis quickly moves back into the region by
Thu, allowing return of mid/high clouds during the day. With
fairly low mixing and overrunning clouds, expect a cooler day
with highs mainly ranging from the upper 50s to the lower 60s.
Kept it dry through 22z despite the increase in clouds.
Long term /Thursday night through Monday/...
good chc for showers and possible tstms later Thu night into
early Sat morning, as low pressure and another associated cold
front approaches and moves acrs the region. Dry wx and high
pressure returns for Sat aftn thru Sun night. Yet another system
may approach FM the west late Mon.
Highs in the upper 50s to upper 60s Fri, in the 60s to near 70
Sat, in the mid 60s to lower 70s sun, and in the 60s to near 70
Mon. Lows in the 40s Thu night, in the upper 40s to mid 50s Fri
night, in the 40s Sat night, and in the mid 40s to near 50 Sun
Aviation /02z Tuesday through Saturday/...
VFR conditions expected for all the taf sites through midnight
and into the early morning. Some patchy fog could develop for
sby/phf/ric during the early morning as low level moisture
continues to increase from the southwest. Some early morning
light rain is also possible especially for western portions of
the County Warning Area but is not expected to be widespread enough to include
in the tafs. Scattered showers and thunderstorms will be
possible during the day on Tuesday, with the potential for a few
storms to be severe Tuesday late afternoon and evening.
Outlook: unsettled weather conditions will continue into Tuesday
night due to the potential for showers and thunderstorms. Sub-
VFR conditions will be possible once again Wednesday morning due
to low ceilings and the potential for fog. Dry/VFR conditions
return on Wednesday as winds shift to the north. The next storm
system is expected to approach the area Friday bringing the next
chance of adverse aviation conditions.
no headlines in the short term tonight thru Wed. Late this aftn,
high pressure was well off the mid Atlc coast while low pressure
was cntrd over srn Illinois/extrm ern Kentucky. The low and its associated
cold front will approach FM the west tonight into Tue morning,
then move acrs the area and off the coast late Tue/Tue night.
South-southwest winds generally 10 to 15 kt will continue tonight into Tue
evening, then become northwest then north Tue night into Wed morning behind
the front. North winds 10 to 15 kt during Wed, as high pressure
starts to build in FM the north. Do not expect Small Craft Advisory conditions to be
met thru Wed. High pressure will continue to build in FM the north
Wed night into Thu morning, then slides out to sea Thu aftn into
Thu night. North-northeast winds 15 kt or less Wed night, then NE 5 to 15 kt
Thu aftn. East winds 5 to 10 kt becoming southeast Thu night.