Area forecast discussion
National Weather Service Blacksburg Virginia
212 am EDT Friday may 24 2013
Synopsis...
a strong cold front will cross the area from the northwest
overnight with drier and cooler air pushing in for Friday into
the weekend. A warm front works north from the Gulf Coast early
next week...followed by strong high pressure bringing more Summer
like weather by middle to late week.
&&
Near term /through today/...
as of 920 PM EDT Thursday...
Wind shift front now nearing the Blue Ridge preceded by a narrow
line of shallow rain showers/thunderstorms and rain that will cross the eastern edge of the
County Warning Area in the next hour. Actual dewpoint front lags back along the
Ohio River denoted by another band of -shra per regional radar
loops. Once the eastern band of rain showers exits...models keep clouds
packed in across the far west as the flow turns more northwest while
getting more clearing east as downslope increases late. Thus will
keep Cat/likely probability of precipitation out east a bit longer and hang onto current
chances northwest slopes overnight espcly given the arrival of the strong
500 mb upper system toward daybreak.
Overnight lows appear on track with cold air advection surging in
behind the secondary front but will see clouds and mixing hinder
big drop in temperatures. Look for lows in the upper 40s across the WV
mountains into the NC mountains...to middle 50s New River valley/Roanoke and
upper 50s/near 60 east.
Models keep clouds over the west tonight into Friday morning while
strong downslope works to dry things out to the east.
Pressure rises on the order of 4-6 mb per 6 hours will be moving
into the area late tonight/early Friday where some gusts could
exceed 40 knots. Low level winds are marginal for Wind Advisory...but
will have to monitor trends to see if an advisory may be needed over
the higher elevations of far SW Virginia into northwest NC Friday.
Airmass will be noticeably drier and cooler Friday with the
breeze...with highs only managing the 60s west to lower 70s east.
&&
Short term /tonight through Sunday night/...
as of 350 PM EDT Thursday...
Cold anomalous upper level trough will move across the eastern Continental U.S.
This weekend providing downright cool conditions for the Memorial
Day weekend. Temperatures this weekend are expected to be 15 to 20
degrees below normal with an opportunity for low temperatures to
test the 30s both Saturday and Sunday morning.
1030 mb surface high is prognosticated to move across the Ohio Valley and
Great Lakes Friday...sliding south and east across the middle Atlantic
region Saturday and Sunday. Cold air advection riding into the area
on brisk northwest winds Friday night will overtake the entire region...dewpoints
slipping into the 20s. In spite of the unseasonably cool
temperatures...mixing from the wind Friday night and abundance of
vegetation...especially the tree canopy...should trap enough long
wave radiation at night to prevent a frost or freeze. The only
area at this time that we think temperatures may slip below freezing for a few
hours would be the WV mountains northwest of Lewisburg.
Elsewhere...unless you just live in a Deep Hole...unprotected
Mountain Valley...would there be a need to take any precaution
from a frost or freeze. Even in these areas...would think plants
near buildings or underneath a porch would fair just fine.
With air temperatures suppressed well below normal for the
weekend...combined with low dewpoints...a swim party at the local
pool is not recommended. Hiking or working out of doors however
look to be ideal...as no rain is forecast and a lot of folks may
prefer the crisper cool conditions for mowing the back yard
hayfields that have been promoted from all the rainfall this past
week.
&&
Long term /Monday through Thursday/...
as of 350 PM EDT Thursday
Looks like we will trade the cool upper trough for a Mammoth Ridge
of upper level high by the middle of next week. Monday and Tuesday
will be transition days with clouds and potential precipitation spilling
into the area around an amplifying area of upper level high
pressure...which will morph from the central Continental U.S.
Monday...overtaking the eastern Continental U.S. By Wednesday. At the
surface...a warm front will move northeast...up through the Ohio
Valley...arcing through the Middle Atlantic States. This feature will
likely be the focus for clouds and potential for showers with
embedded thunderstorms Monday and Tuesday. The front should gain
latitude Tuesday and finally put US completely in the warm sector
by Wednesday. For Wednesday and Thursday it will be back to
really warm temperatures and higher humidity with the threat for airmass
showers and thunderstorms mainly during the peak heating hours.
&&
Aviation /06z Friday through Tuesday/...
as of 200 am EDT Thursday...
Thunderstorm activity has exited the area for the remainder of
the weekend...and will now contend with a strong cold front that
will cross the area this morning. With the cold air building in
behind the front...will see a short period of low MVFR/IFR
ceilings from roa westward...that will gradually improve through
sunrise. By late morning...expect to see low clouds scatter for
these airports...resulting in VFR conditions through the remainder
of the day. Further east...lyh and Dan are expected to remain
VFR.
The main concern for this taf period however will be gusty winds
as the pressure gradient increases to around 8 mb across the
forecast area after sunrise. As such...will be looking at wind
gusts as high as 30 kts for bcb...blf and lyh....and up to 25 kts
for Dan and lyh. Wind direction will be near perfect for terrain
induced funneling at roa...and would not be surprised to see gusts
top out near 40 kts during early afternoon.
Expect to see wind speeds diminish during the evening...however
the pressure gradient will remain tight as low pressure off the
coast of New England deepens. As such...wind gusts across the
mountains will remain as high as 15 to 20 kts through Friday
night... before wind speeds diminish on Saturday.
High pressure to keep US VFR through the weekend. Moisture
increases again next week as the surface high moves east and the upper
ridge strengthens over the Mississippi Valley. Will be getting to
more humid weather again with some thunderstorm threat by Tuesday
and fog issues at night in the valleys.
&&
Rnk watches/warnings/advisories...
Virginia...none.
NC...none.
WV...none.
&&
$$
Synopsis...wp
near term...jh/wp
short term...PM
long term...PM
aviation...jh/nf
