Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Blacksburg Virginia
356 PM EDT Wednesday Oct 22 2014
low pressure off the Delaware-Maryland-Virginia coast will strengthen into a nor-
Easter that will pelt New England with heavy rainfall and wind
through the end of this week. Backlash from this system will be
felt across our region through Thursday in the form of variable
amounts of cloud cover...and cool northwest winds. A moderating
trend will occur over the weekend as the storm system moves away
from the area...replaced by high pressure that will bring warming
conditions for the weekend...and above normal temperatures for the
last week of October.
Near term /through Thursday/...
as of 330 PM EDT Wednesday...
An upper level low will move off the Virginia coast this evening then
drift to the northeast through the day Thursday. Short waves
tracking around the center will bring a chance for rain to the rnk
Piedmont...east of Highway 29...into this evening. Short waves on the
outer rings are lacking moisture but with an upslope component could
bring light rain/drizzle to western slopes of southeastern West
Virginia through tonight. Rain chances decrease overnight and into
the day Thursday as the low drifts farther away from the forecast
area. Also as this low moves away from the area...clouds will
decrease from the southwest to the northeast. Clouds today have kept
winds speeds down a bit but with clearing skies and a pressure
gradient remaining over the region Thursday...breezy and gusty
conditions likely. Developing inversion overnight will keep stronger
winds aloft and should start mixing down after 10 am Thursday as the
inversion lowers/breaks. Wind gusts of 20-30 miles per hour are possible
especially along the Blue Ridge.
Downsloping flow helped warm temperatures in the east...especially
Southside this afternoon. This downslope warming and abundant
sunshine should warm the foothills and Piedmont counties into the
M/u 60s Thursday. Cool northwest winds will Keep Mountain
temperatures in the M/u 50s. A few locations tonight will fall into
the 30s. With overnight mixing...no frost is expected in these areas.
Short term /Thursday night through Saturday night/...
as of 345 PM EDT Wednesday...
The Upper Cutoff low along the New England coast will slowly drift
away from the area Thursday night...winds diminishing...skies
clearing. If the winds diminish quick enough...temperatures may
dip into the lower 30s in the mountain valleys...allowing for some
patchy frost for daybreak Friday.
For Friday...high pressure will try to build across the forecast
area but any significant height rises will be delayed until the
passage of a short wave trough late Friday. The actual surface
front lags the upper trough and moves through the area Saturday.
Both features will be moisture starved...models indicating some
middle/upper level cloudiness with the passage of the upper trough
Friday...and some low level cloudiness associated with the
passage of the surface front Saturday. Model soundings indicate
moisture above 700 mb Friday with potential for virga but no quantitative precipitation forecast.
Clouds Saturday will be mainly confined to the western slopes of
the mountains...again no quantitative precipitation forecast. Temperatures both Friday and
Saturday will be tempered by the cloud cover. However...readings
should still be close to the seasonal norm. There is a surge of
wind behind the front Saturday...models suggesting breezy
northwest winds for Saturday afternoon through Sunday morning.
Long term /Sunday through Wednesday/...
as of 345 PM EDT Wednesday...
An upper level ridge of high pressure will build across the
forecast area for the first half of next week...500 mb heights
increasing each day until the passage of a trough middle/late week.
This will translate into warmer than normal temperatures with
highs in the 60s mountains...and well into the 70s Piedmont.
Next chance of showers will accompany a frontal passage in the
Wednesday Thursday time frame. With warmer than normal
temperatures...no threat of frost next week.
Aviation /20z Wednesday through Monday/...
as of 105 PM EDT Wednesday...
Closed low will drift off the Delaware-Maryland-Virginia coast this afternoon...and
will be the primary focus for weather throughout the region
through the taf period. This feature will result in the
development of a nor-Easter that will pelt the New England coast
with heavy rain and wind...and will most likely impact air traffic
for many of the New England terminals for the remainder of this
For our local region...bkn-ovc cloud bases will be common through
tonight across the mountains with LIFR ceilings for blf and MVFR at
lwb/bcb...VFR east. Scattered showers and/or drizzle are possible
along western slopes through the afternoon. Conditions will
approve through the night with VFR conditions for everyone by
With the developing cyclone to our northeast...backlash will be
felt throughout our region in the form of gusty northwest winds.
3000- 5000ft above ground level winds of 40 kts are prognosticated through this evening.
With clearing in the east...mixing will be more likely and
terminals can expect 20-30kt surface gusts. With developing
inversion overnight winds will decrease in the lower elevations
and remain along ridgetops. Inversion will break tomorrow morning
with breezy and gusty winds into the afternoon.
Medium confidence in ceilings...visibilities and winds during the
Extended aviation discussion...
The upper level low will slowly meander off the middle-Atlantic
coast Thursday...then begin to shift toward the northeast and away
from the area by Friday. High pressure builds over the region
Friday...with dry VFR conditions remaining into Tuesday.