Area Forecast Discussion
Issued by NWS Blacksburg, VA

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FXUS61 KRNK 300818

Area Forecast Discussion
National Weather Service Blacksburg VA
418 AM EDT Tue May 30 2017

Series of fronts will cross the Mid Atlantic region today through
Wednesday. Wednesday night the strongest front will push into the
region followed by cooler and drier air. Showers and thunderstorms
return to the area Saturday and Sunday ahead of a developing low
pressure system in the Ohio Valley.


As of 400 AM EDT Tuesday...

Little change in the southeast synoptic flow and location of the
large upper low over the northeast United States today or tonight.
Highest probability of precipitation will be from North Carolina
into eastern Virginia where surface dew points will remain in 60s
and there is potential for higher CAPEs with any heating today. Axis
of precipitation from west South Carolina to southeast Virginia this
morning was along a weak front. Models show bulk of lift and deeper
moisture east of Danville after 15Z/11AM.

Trof/weak front will drift toward the region from the northwest
today. Wind shift may cross the Mid Atlantic states today but not
real change in air mass across this boundary. Cluster of showers and
thunderstorms over western Kentucky may reach the central
Appalachians this afternoon. Hi-Resnmm, Hi-Resarw and NAMnest
showed this solution. Given the slow southeast progress of the
front, this precipitation may not reach the region until after

Guidance has been running too warm for maximum temperatures the past
few days. Starting out with abundant cloud cover this morning so
have trimmed maximum temperatures for this afternoon. With no change
in air mass, lows will be similar to past few nights. Bias corrected
guidance accounts for this trends. Kept lows tonight generally in
the mid 50s to mid 60s.


As of 250 AM EDT Tuesday...

A broad upper level low pressure system covers the majority of the
area east of the Rockies Wednesday. Meanwhile, a Bermuda high
resides in the western Atlantic. Both the low and the high will
slowly move east during the day Wednesday. The upper low will
eventually send a cold front over the region during the late
afternoon, clearing the piedmont in the evening. Along with lift
from the front, modest instabilities will bring showers and
thunderstorms to the region. The higher instabilities for the area
will be east of the Blue Ridge where less clouds and maximum heating
will occur for the day. High temperatures will range from the mid to
upper 70s across the mountains to the low to mid 80s east. The
piedmont maybe flirting with highs in the upper 80s by the time
convection rolls through. The low level jet is not overly strong,
however winds will back to the southwest to help the potential for
some strong storms to develop along the Blue Ridge and into the
foothills during the afternoon. Diffluence aloft is best over the
piedmont which should help promote isolated severe storms between 4p-
7p for areas along and east of hwy 29. The surface front will move
to the Mid Atlantic coast by midnight then the dew point front will
follow about 6 hours later. Since the dew point front lags behind,
we kept clouds in a little longer overnight.

High pressure and sunny skies expected Thursday with highs in the
70s west of the Blue Ridge to the lower 80s east. Dry conditions
will continue into Friday morning as high pressure skirts over the
region. Southerly flow returns Friday afternoon along with the
chance for afternoon and evening thunderstorms. Highs Friday will
range from the upper 70s west to mid 80s east. Dew points Friday
will also creep back into the 60s.


As of 100 PM EDT Monday...

Forecast area then becomes embedded in a zonal, confluent mid-level
flow for a large part of late week into the weekend. This is
modulated by two primary 500 mb features: a persistent mid/upper-
level low and cyclonic flow over the Northeast/Great Lakes, and
increasing troughing over the Four Corners leading to greater
southwest flow and warmer/more humid conditions from the Plains
into the Tennessee Valley.

Warmer and increasing humidity levels can be expected through the
upcoming weekend, along with a return to a wet weather pattern in a
general sense. Timing weak shortwave troughs/vorticity maxima in the
confluent flow is difficult; and as such, I`ve kept chances for PoPs
lingering through the upcoming weekend into early next week.


As of 135 AM EDT Tuesday...

Stationary front extended from a low in central Virginia to
northern Alabama. Expect little movement of the front through
12Z with scattered showers along the boundary. KDAN may have
occasional MVFR visibilities.

Otherwise mid and high clouds will cover the Mid Atlantic area
this morning. Another front expected by this afternoon will
bring a chance of showers to the mountains, but overall
conditions will be VFR.

Locations that have rain early this morning may have MVFR fog
before 12Z but confidence in extent of fog is low.

Extended Aviation Discussion...

Overall VFR expected for mid and late week before showers and
storms increase later Friday into Saturday. Exceptions will be
any late night river fog, or shower/wet ground induced fog.

Next threat of shower/storms Wednesday with yet another front
and decent upper support, so will have to watch for stronger
convection but appears any sub-VFR will be brief and mainly over
the mountains.

Thursday looks dry then more potential for scattered afternoon
and evening storms Friday through the weekend with the best
coverage on Saturday when more sub-VFR will be possible.




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