Area Forecast Discussion
Issued by NWS Blacksburg, VA

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FXUS61 KRNK 260107

Area Forecast Discussion
National Weather Service Blacksburg VA
907 PM EDT Mon Sep 25 2017

High pressure over the eastern United States will continue to
bring mainly warm and dry weather to the region through midweek,
while Hurricane Maria stays just off the east coast. A dry cold
front will move through the Appalachians and mid Atlantic
region on Thursday, with much cooler weather for the end of the
workweek into next weekend.

As of 850 PM EDT Monday...

Evening soundings show some uptick in low level moisture since
last night given deep easterly flow to the northwest of Maria.
However clouds continue to diminish within the extensive dry air
aloft, with mainly swaths of high canopy spreading to the north
of the area. This while most strato-cu bands remain well to the
south and east with perhaps some of this reaching the far
eastern/southern sections late per latest Blended TPW loop.
Otherwise less clouds and light winds should promote a little
more in the way of fog in the valleys overnight espcly given
rather moist dewpoints across the region. Thus adjusted fog
coverage a bit late and kept low temps in line with the earlier
EC mos which is a little warmer than last night.

Previous discussion as of 245 PM EDT Monday...

Fair weather pattern continues with high pressure surface and
aloft yielding warm and dry conditions across the region. Expect
the veil of cirrus from Maria off the coast to gradually wane
through tomorrow. This should allow for better cooling and more
coverage of fog west of the Blue Ridge overnight.

Fair and warm conditions continue for Tuesday with a northeasterly
breeze. Low level moisture will also be on the increase and help
generate some lower clouds, but do not anticipate enough instability
or orographic forcing to generate any precipitation so will continue
with a dry forecast

Lows tonight will generally be in the low to mid 60s east of
the Ridge with mid/upper 50s to the west along with some cooler
readings in the valleys. Highs Tuesday will be in the mid/upper
80s east, low/mid 80s west.


As of 304 PM EDT Monday...

Really not much change this forecast as Hurricane Maria shifts north
and weakens well east of the Outer Banks, then heads northeast as
the upper trough and associate front move across by Thursday
morning. This front should be limited in moisture so not putting any
chance of showers. Will see some clouds and thats about it.

Wednesday looks to be the last day of summer like
temperatures/dewpoints with highs in the upper 70s to lower 80s in
the mountains, to mid to upper 80s east. Lows Wednesday night still
above normal with upper 50s to lower 60s west, to lower to upper 60s

Slightly cooler with less humidity Thursday with a little more
breeze out of the northwest. With partly to mostly sunny skies highs
will range from the mid to upper 70s west, to lower to mid 80s east.
Dewpoint temperature should drop into the lower to mid 50s most
places by mid-late afternoon.

Seasonably cool Thursday night with lows in the upper 40s to lower
50s west, to mid to upper 50s east.


As of 203 PM EDT Monday...

500 MB trough digs across the Great Lakes into our area Friday into
Saturday with high pressure starting to shift southward from the
Great Lakes into Sunday. Will be a dry/cooler with temps close to or
below normal. Later Sunday into Monday the flow turns more northeast
as the high wedges southward. Should start to see clouds increasing
Monday especially as the flow turns more east off the ocean. At the
moment confidence in any showers is low, so keeping pops below 15


As of 655 PM EDT Monday...

No change with overall good flying conditions expected to
continue overnight through Tuesday with high pressure surface
and aloft in place. This will yield mainly VFR conditions under
some high cirrus clouds as well as passing scattered strato-
cu into tonight. Only exception being late night valley
fog/stratus west of the Blue Ridge, possibly resulting in a
period of IFR cigs/vsbys at KLWB and KBCB. Latest ensembles
showing a bit more potential for fog/stratus than last night
given some increase in dewpoints and perhaps a period of
clearing behind the current axis of high clouds this evening.
However given dry air, backed off on widespread sub-VFR, while
leaving IFR/LIFR cigs/vsbys within a late night TEMPO scenario
at both locations.

Any fog/stratus dissipates Tuesday morning with VFR through the
end of the valid period. However some increase in lower VFR
cigs possible east of the Blue Ridge Tuesday afternoon as bands
of strato-cu push inland around Maria well offshore.

Winds will generally be light north to northeast, though
northeasterly flow around Maria off the east coast will amplify
winds, and generate some gusts to around 20 kts at times mainly
east of the Blue Ridge Tuesday.

Lower cigs may develop espcly along/east of the Blue Ridge
Tuesday night into Wednesday as Maria makes it closest approach
offshore the Carolinas. Latest guidance suggests a swath of VFR
to MVFR cigs may advect farther inland on increasing northeast
flow with at least a period of sub-VFR possible east of the
mountains by early Wednesday.

Extended Aviation Discussion...

Maria should exit farther offshore Wednesday night into Thursday
ahead of a cold front that looks to cross the region from the
west during the day. Front appears mainly dry with just a band
of upslope aided low clouds possible behind the front Thursday
before much drier post frontal air swings in on northwest winds
later Thursday into early Friday. Strong high pressure then
follows the boundary with continued VFR outside of added upslope
clouds far west Friday through Saturday.




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