Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wakefield Virginia
1136 am EDT Monday Mar 10 2014
high pressure will be centered south of the area and off the coast
this afternoon through Tuesday. Low pressure approaches the middle
Atlantic region Tuesday night. An associated warm front becomes
located across northern Virginia Wednesday morning with the
trailing cold front crossing the area Wednesday afternoon.
Canadian high pressure builds into the area late Wednesday night
Near term /until 6 PM this evening/...
hi pressure dominates from the Gulf Coast to the middle Atlantic region during
today. A weak trough will slide into and across the area this afternoon
into this eveng. This was producing and will continue to result in
hi and middle level clouds...thicker across the northern half of the region.
Despite west-southwest surface winds...these clouds could limit warming and will
esply monitor temperatures over the northern cnties this afternoon. Otherwise...nice
and dry conditions with maximum temperatures ranging from the upper 50s to near
Short term /6 PM this evening through Wednesday night/...
tonight through Tuesday night...
the cloud cover will break up briefly this evening but then stream
back over the northern half of the County Warning Area overnight as a low pressure system
tracks into northern New England from the northern Great Lakes overnight.
Continued SW winds will advect warmer air into the region and lows
should only drop into the middle-upper 40s. High pressure still
dominates on Tuesday as another surface low moves into the middle
Mississippi River valley. A warm front will extend across northern Virginia
from this feature and will promote additional warming across the
area on Tuesday. Expect highs in the low-middle 70s most areas (upper
60s Northern Neck and Maryland/Virginia eastern shore). 00z model runs are still in
good agreement with moving this system across the Tennessee Valley Tuesday
night. This will put the middle Atlantic region within the warm sector
ahead of the advancing cold front. Increasing dewpoints and
increasing cloud cover overnight will keep temperatures above normal with
lows in the upper 40s to lower 50s. The onset of precipitation has been
delayed by about 6 hours over the past two nights of model runs and
have kept a dry forecast for Tuesday night.
Wednesday and Wednesday night...
the warm front in northern Virginia lifts farther northward on Wednesday as the Tennessee
Valley low moves into the Middle Atlantic States. The cold front is
expected to cross the region Wednesday aftn/evening. Isentropic lift ahead
of the front will bring showers into the Piedmont (west of
Interstate 95) Wednesday morning...which will then push to the coast
by Wednesday afternoon. Since the area will be well within the warm
sector ahead of the front...temperatures should be able to reach the upper
60s to lower 70s south/middle 60s north due to low level
mixing...especially during the afternoon despite overcast skies. The
abundant cloud cover will likely limit any thunder potential
Wednesday afternoon due to a lack of upper level jet support and weakly
unstable surface lapse rates/Cape. Cross sections also reveal that best
Omega/lift is elevated at best. Overall...any thunderstorms that
develop within the warm sector will be shear and instability
dependent...and even then more favorable parameters are only located
right along the cold front. Precipitable waters increase from 0.50-0.75 inches
Wednesday morning to 1.25-1.40 inches by Wednesday afternoon. In
addition...saturated model soundings suggest that moderate to heavy
rainfall will be possible. Therefore thunderstorm wording has been
limited to slight chance wording. If any thunderstorms develop...the
primary threats will be periods of strong gusty winds and heavy rain.
The cold front exits the coast Wednesday evening and precipitation is
expected to end from west to east through the night. A colder
Canadian airmass will filter into the region late Wednesday night...
especially once west-SW winds become northwest. Precipitation may quickly change
over to snow across the Maryland/Virginia Eastern Shore late Wednesday evening
as the cold air undercuts the departing low. Otherwise...cold air advection will
produce gusty winds areawide Wednesday night with higher gusts
along the ches Bay and Atlantic coasts. Temperatures are expected to drop
into the middle-upper 20s northwest to lower 30s southeast but should only fall
quickly after midnight when the northwest winds develop.
Long term /Thursday through Sunday/...
going with a general blend of the 12z GFS and 12z European model (ecmwf) for the
extended period. Low pressure and associated cold front push east-northeast and
off the CST Wednesday night into Thursday morng. Rain showers end from west to east Wednesday
eveng/early Wednesday night...and the precipitation could end as a mix of a rain
and snow shower over the lower Maryland and Virginia eastern shr. Then...strong northwest
winds will usher a much drier and colder airmass into the region
for late Wednesday night through Thursday. Becoming clear to partly cloudy Wednesday night
with lows in the upper 20s to middle 30s. Generally mostly sunny on Thursday
with highs only in the lower to middle 40s...as hi pressure builds in from the
west. The hi will build across the area then out to sea Thursday night through
Friday...maintaining dry weather. Clear and cold Thursday night with lows in the
lower to middle 20s. Mostly sunny on Friday with maximum temperatures rebounding back
into the 50s. A dry front will cross the region Sat night into sun
morng...with another low pressure system pushing into the Tennessee/Ohio valleys
by late sun. Keeping dry weather forecast for Friday night through sun. Lows Friday
night in the middle 30s to near 40. Highs on Sat in the upper 50s to middle
60s. Lows Sat night in the middle 30s to lower 40s. Highs on sun in the
middle 50s to lower 60s.
Aviation /16z Monday through Friday/...
VFR conds expected through the taf period (light and variable winds
become SW ~10kt this aftn).
Outlook: surface low pressure tracks from the Tennessee Valley through the
northern middle-Atlantic late Tuesday/Wednesday before shifting off the coast
late Wednesday. Expect MVFR conds (brief periods of ifr) with rain showers
possible, especially at kric/ksby. VFR conditions return by early
Thursday with gusty northwest winds.
no headlines in the short term today through Tuesday night/Wednesday morning. Winds will
be 15 knots or less. Waves will be 1 to 2 feet...and seas will be 2 to
3 feet. Increasing south-southwest winds expected during Wednesday in advance of low pressure
and associated cold front...with the possibility of Small Craft Advisory conditions over
portions of the marine area. That low and its associated cold front
will push east-northeast and off the CST Wednesday night into Thursday morng. Strong low
level cold air advection will then result in very strong northwest winds over the marine
area late Wednesday night through Thursday. Hi probability for Small Craft Advisory conds expected west/ gale
conds also a possibility.