Scientific Forecaster Discussion
fxus61 krnk 140810
Area forecast discussion
National Weather Service Blacksburg Virginia
310 am EST Thu Nov 14 2019
high pressure over the eastern U.S. Will remain in control
today with low pressure developing along the southeast coast
by early Friday. This will bring clouds and a chance for light
precipitation to the Piedmont. Temperatures will moderate over
the next few days.
Near term /through tonight/...
as of 300 am EST Thursday...
A split flow pattern is evident in the mid-tropospheric flow
across the Continental U.S. Early this morning with the mid-
Atlantic/southern appalachian region in the middle. A developing
storm system over the southeastern U.S. Offers the best Prospect
for sensible weather over any part of our region in the near
term, mainly across the far southeastern counties. An upper
level system closes off at h5 over MS/Alabama and the surface low
begins to take shape off the northeast Florida coast by early Friday
with clouds on the increase, especially across the southeast, in
association with the developing coastal low. Pops are increased
to high chance over the extreme southeastern County Warning Area by early
Friday morning but quantitative precipitation forecast appear to be very modest, less then 0.25
inches in the extreme southeast and diminishing fairly rapidly to
the northwest. Temperatures at this point appear to be just
warm enough for all rain in most of the Piedmont where
measurable amounts are forecast, but some mixed precipitation
along the northwest edge of the precipitation shield is possible
with the sub-32f dewpoints and possible wet-bulb effects. This
will have to be monitored as the situation develops and will
depend heavily on the eventual track and strength of the coastal
Meanwhile a cold front will also cross the area over the next
24 hours but with a much less extreme air mass behind it, but
maintaining dry conditions across most of the region, with the
exception of the far southeast as mentioned above. Highs today
still running 5 to 10f below mid- November climo, mid-40s northwest to
mid- 50s southeast but lows tonight just slightly below climo, mid-20s
northwest to mid- 30s southeast.
Short term /Friday through Sunday/...
as of 200 am EST Thursday...
A coastal low should track northeastward from the Florida coast to
the North Carolina coast during Friday. While the bulk of the
moisture will stay along the Atlantic shore, parts of Southside
Virginia and the North Carolina Piedmont may see light rain
lingering into the morning that eventually tapers off by the
afternoon. Meanwhile, a steady north breeze will begin to advect
cold and dry air from high pressure crossing over eastern Canada.
Overall, the models are fairly confident that the coastal low will
deepen and start to pull moisture away from the mid Atlantic on
Friday night, so expect a slow but steady decrease in cloudiness. It
is Worth noting that the GFS is a little more optimistic with
pushing the moisture further east than the European model (ecmwf).
By Saturday, high pressure should reach northern New York, while a
second coastal low develops along the frontal boundary left over
from the first coastal low. This increase in pressure gradient
between the second coastal low and high pressure to the north will
result in a more notable northeast breeze, especially along and east
of the Blue Ridge. That breeze will persist into Saturday night,
which will aid in advecting more dry air as depicted by the
dewpoints falling into the teens by Sunday morning. The second
coastal low should deepen and pull any leftover clouds east of the
Piedmont by Sunday afternoon. Consequently, confidence is increasing
that conditions will become dry for this upcoming weekend, but it
will still feel rather chilly with temperatures remaining below
normal for the middle of November.
Long term /Sunday night through Wednesday/...
as of 250 PM EST Wednesday...
An occluded low may wobble off the southeast coast Saturday night
then moves out to sea on Sunday. High pressure wedges in from the
north and should keep the region dry through Monday night. A large
upper level trough will track across the US early next week and may
bring rain to the area Tuesday or Wednesday.
Models differ slightly on a disturbance coming out of the Gulf,
tracking north along the coast. The ecm has a more amplified trough,
swinging a closed low close to the area Tuesday night and Wednesday,
then becomes a noreaster off the New England coast on Thursday. The
GFS is less robust on the Gulf disturbance until it moves to the New
England coast to become a noreaster. Either way, both solutions
produce little to no rain for the area. Temperatures are also warm
enough that any precipitation will fall as rain.
Temperatures will remain cooler than normal through Tuesday.
Temperatures will be close to normal on Wednesday.
Aviation /08z Thursday through Monday/...
as of 1200 am EST Thursday...
VFR conditions expected through the entire taf valid period. A
large area of cold and dry surface high pressure will remain
over the area through early Friday as it pushes slowly southeast
during this time frame. High clouds will stream across northern
areas tonight from a northern stream disturbance moving from the
Great Lakes into New England while another batch of high clouds
skirts across the southern parts of the area due to a southern
stream system moving east-northeast out of Texas. The northern
stream system will move out to sea Thursday while the southern
stream system intensifies, begins to pick up deeper Gulf
moisture and spread northeast into Georgia/SC by early Friday and
then toward the NC coast by Saturday. Expect increasingly dense
mid/high clouds as a result toward the end of the taf valid
period, but cigs will remain aoa100. The latest GFS advertising
potential for low end VFR ceilings creeping north into the
Dan/mtv/w78 area late Thursday/Thursday evening. This seems a
bit agressive, but plausible. Thus, added a group for 050bkn at
kdan late in the taf valid period. Visibility will not be an
issue through 06z Fri anywhere and no precipitation was
advertised at this time.
Winds will be mostly light NE-southeast across the region tonight,
speeds 5kts or less, then light and variable Thursday, but
trending toward the SW 5kts or less.
/Confidence levels in forecast parameters/
ceilings - high,
visibilities - high,
winds - moderate.
Extended aviation discussion...
Models showing potential southeast coastal system moving
moisture toward Dan Thursday night-Friday which could bring
ceilings toward low end VFR. VFR conditions expected Saturday
and Sunday. Some rain on Monday may bring some MVFR conditions.
as of 230 am EST Thursday...
Looking at climate records for November 14 below it appears
than Danville and possibly Lynchburg have a chance to reach a
record low later this morning, but unlikely at the other climate
sites. That should do it for records from this unusual but
brief early season cold snap.
site record lows/year