Scientific Forecaster Discussion
fxus61 krnk 161953
Area forecast discussion
National Weather Service Blacksburg Virginia
353 PM EDT Wed Oct 16 2019
an area of low pressure will strengthen along the New England
coast tonight and Thursday then move northeast into the Canadian
Maritimes. In its wake expect strong gusty winds and much colder
temperatures. Winds will diminish by Friday as high pressure
passes overhead. Another opportunity for rain is expected as
early as Saturday night as an area of low pressure moves out of
the Gulf of Mexico and to along the southeast Atlantic coast.
Another cold front will cross the mid-Atlantic region Monday
night into Tuesday, providing yet another opportunity for rain.
Near term /through Thursday/...
as of 345 am EDT Wednesday...
Can't complain about the rain in spite of receiving 2x forecast.
Wednesday's frontal passage produced, on average, an inch /1.00/
of rain across Virginia and West Virginia, and a quarter /0.25/
to a half /0.50/ inch across North Carolina.
The front is now east of the forecast area, and once it passes
off shore, it will interact with the Gulf Stream in addition to
getting an energy boost from the parent low crossing Ontario.
This is expected to spawn a rapidly deepening surface cyclone
near the New England coast, and steepening the pressure gradient
across our region. As a result, the gusty northwest winds which
have already developed in the wake of the front will become
stronger and gustier with time as we transition into the
overnight. With 85h winds (3000-4000 ft msl) progged near 50
kts, would expect the strongest winds and wind gusts to occur
along our ridge crests overnight and into the day Thursday where
gust of 35 mph to as much as 50 mph should be common. A Wind
Advisory is in place to reflect this, and no change in areal
coverage is expected attm.
Clearing that has materialize behind the front will be replace
by some low level cold air advection cloud cover over the
mountains. The forecast soundings indicate the moisture will be
rather shallow, but can't rule out some sprinkles and or
flurries (pending temperature) for the overnight and into the
day Thursday. The temperature change between now and daybreak
Thursday will be quite noticeable, with temperatures ranging
from the lower to mid 30s in the mountains to the lower to mid
40s in the Piedmont. Mountain locations above 3500 feet may very
will reach 32 degrees overnight, but the winds will be too
strong for frost formation. That said, wind chills for these
higher locales will be in the 20s, so the feel to the air may
be more winterlike.
The wind gradient will gradually relax Thursday, but given the
persistence of the pressure rises, the day as a whole will be
blustery. Where the clouds persist over the mountains, it will
be blustery and cold, high temperatures struggling to get into
the 40s for the higher elevations and generally getting no
warmer than the 50s, touching 60 for the Piedmont... about 10
degrees below the norm.
Short term /Thursday night through Friday night/...
as of 200 PM EDT Wednesday...
The main thing to note starting off this part of the forecast
is that guidance is still placing a decent amount of wind
overnight Thursday into Friday. While the surface high starts to
move into our area, models are still placing a fair amount of
wind overnight as our cloud cover starts to drop. Because of
this, I am going with no chances of frost, despite some regions
dropping below freezing. Winds just seem to strong right now to
think of any real frost to mention. Perhaps a few isolated areas
could still get some though, but it is not Worth placing in our
For Friday, the surface high moves over the area, bringing
pleasant temperatures (upper 50s to 60s). Friday night brings
the real threat of any widespread frost, which is still going to
remain limited more in Mountain Valley areas. Radiative cooling
is going to allow for quick temperature drops overnight, but
not substantially as warm air advection aloft is still expected.
Hence the limited frost development.
Long term /Saturday through Wednesday/...
as of 200 PM EDT Wednesday...
Guidance for this weekend has gone through serious changes over
the past 24 hours. Model spread has increased when it comes to
handling a low pressure system that will be coming across the
Florida Panhandle and move northeast along the Carolina's. This
system will be following behind the exiting surface high
Saturday morning. Should the ever increasing in speed GFS come
true, we could see moisture arriving much earlier Saturday, mid
to late afternoon. The Euro seems to keep things a little
slower, holding moisture return off until Saturday night. Our
rain chances through this period will also depend on track, as
guidance has been rocky on how far east it wants to move the
system as it starts to get picked up by the upper level flow
pattern. Should the system remain further east, rain chances and
quantitative precipitation forecast would remain lower. For now, keeping rain chances off until
Saturday night, then bringing them up. Likewise, I am keeping
them low until we get a better idea on east/west track with this
system. Certainly plan on this part of the forecast to change.
There will be little transitional time between the first wave
of rain associated with the Gulf low and another front that is
poised to move through Monday into Tuesday. If our rain from the
weekend isn't enough for you, this front looks to take another
chip off our fading drought conditions with up to an inch of
rain possible out of it. Temperatures through the weekend and
before the frontal passage look to range in the upper 50s to 60s
for highs and upper 40s to mid 60s for lows (besides obviously
Saturday morning as previously mentioned).
Aviation /19z Wednesday through Monday/...
as of 715 am EDT Wednesday...
Aviation weather/conditions will be sub-VFR this morning into
early afternoon before a front moves across lifting ceilings to
VFR and scattering them out. Rain will be affecting all sites
this morning, then dry this afternoon.
West-northwest winds pick up after 18z and especially this evening after
00z, sustained 10-15kts with gusts up to 35kts at taf sites,
mainly in the mountains. Winds will stay up through the duration
of this taf valid period.
As upslope flow increases tonight, look for sub-VFR cigs again
at blf/lwb and perhaps as far east as bcb.
Confidence is above average for sub-VFR ceilings/vsbys this
morning and above average for timeline of rain and winds.
Confidence is average for ceilings in the west tonight.
Extended aviation discussion...
Very gusty winds will continue into mid morning Thursday.
Thursday afternoon into Friday, the pressure gradient slackens
and winds trend weaker. Once the upslope weakens, the clouds
will erode in the mountains. This may not be until Thursday
night at blf/lwb. VFR conditions are expected regionwide into
There is the potential for some light precipitation and sub-VFR
conditions across parts of the area on Sunday, but confidence
is not high at this point.
Confidence in the forecast for Thursday through Saturday is
wednesday's frontal passage produced, on average, an inch
/1.00/ of rain across Virginia and West Virginia, and a quarter
/0.25/ to a half /0.50/ inch across North Carolina.
The cold front that brought the rain is now east of the
forecast area. In its wake, expect gusty northwest winds with
falling temperatures. These winds will continue through
Next chance of rain is anticipated as early as Saturday night.
The weather pattern has changed and is now expected to feature
routine frontal passages every 4-7 days, associated with both wind
and wetting rainfall...closer to a normal sort of weather pattern
as we transition into November. The stagnant high pressure that
blocked our opportunities for rain during the last 2 months has
abated. As such, we are expecting a trend toward wetter frontal
passages with improvement in the drought conditions, and aid in
muting the fire danger.
Virginia...Wind Advisory until 11 am EDT Thursday for
NC...Wind Advisory until 11 am EDT Thursday for
WV...Wind Advisory until 11 am EDT Thursday for