Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wakefield Virginia
941 PM EDT Monday Sep 15 2014
a cold front will approach from the northwest overnight...before
crossing the middle Atlantic coast Tuesday morning. High pressure
builds north of the region Tuesday night through Thursday as low
pressure lingers along the southeast coast.
Near term /until 6 am Tuesday morning/...
middle-evening infrared/WV Sat imagery showing a dampening middle level
shortwave trough tracking across the eastern Great Lakes into the
northeast. To the south, another weak shortwave aloft was noted
pushing across the eastern Tennessee Valley towards the western
Carolinas. At the surface, weakening surface high pressure remains in
place across the middle-Atlantic coast this evening, as the surface cold
front was analyzed just east of kstl at 00z...trailing back
southwest towards the southern High Plains.
Have continued a slight chance to low chance pop for some light
rain showers/sprinkles after midnight tonight as the shortwave trough
races into New England overnight. The trailing cold front is
expected to enter the northwest portion of the area late tonight...and
reach the Eastern Shore after sunrise. The primary lift associated
with the trough will remain well north of the local area. Given
this...forecast probability of precipitation for most of the area will be no higher than
20% (beginning after midnight). The one exception will be the Eastern
Shore...where 30% probability of precipitation will be forecast (mainly late...between
09-12z) as a weak low-level Theta-E ridge interacts with the
trough passing to the north. Low temperatures are expected to range
from the upper 50s north...to the low/middle 60s southeast. Sky condition will
average out mostly cloudy early...clearing late across the west
behind the departing disturbance.
Short term /6 am Tuesday morning through Thursday/...
low-level drying in a northwest wind is expected behind the front
Tuesday...with the exception of coastal southeast Virginia/NE NC where the tail
end of the trough will be slow to exit the coast...and the wind will
shift to NE. 20-30% probability of precipitation will be maintained to account for this.
Otherwise...expect partial clearing with high temperatures ranging
from the upper 70s across the far northern counties/Atlantic coast...to
the low/middle 80s over interior S-central Virginia/NE NC.
High pressure presently over the northern plains will build north of the
region Tuesday night through Wednesday. Another high north of the Great
Lakes then builds toward the region Wednesday night into Thursday.
Meanwhile...low pressure will linger in vicinity of the southeast
coast. This pattern will maintain persistent NE flow and result in
mostly cloudy to overcast conditions over southern portions...with partly
to mostly cloudy conditions over northern portions. Not much forcing is
expected Tuesday night through Tuesday...so widespread rain showers are
unlikely. However...a 20% pop will be forecast over far southern/southeast Virginia
and NE NC to account for any rain showers creeping north for eastern NC. Highs
should generally range through 70s Wednesday and Thursday. Lows
Wednesday morning should range from the middle 50 north...to low 60s
southeast...with low/middle 50s north low 60s southeast Thursday morning.
Long term /Thursday night through Monday/...
large area of hi pressure will build across southeast Canada and off the New
England CST Thursday night through Sat...with a weaker piece of the hi
remaining over the Middle Atlantic States Sat night through sun. A period
of on shore/NE-E winds expected from Thursday night into Sat...with mainly dry
and autumn-like conditions. Flow will turn to the southeast then S for
late Sat into sun morng...then south-southwest Sun afternoon into Monday morng in
advance of a cold front. Mainly dry weather continues Sat night through Sun
night...before the cold front moves into the area and brings at
least a slight chance of showers on Monday.
Min temperatures will range through the 50s into the lower 60s Friday and Sat
morngs...range from the middle 50s to middle 60s sun morng...and range
through the 60s Monday morng. Maximum temperatures will be in the lower to middle 70s
Friday...in the middle to upper 70s Sat...and range from the middle 70s to lower
80s sun and Monday.
Aviation /02z Tuesday through Saturday/...
winds have turned to the south as surface high pressure has moved
off the coast. A weak cold front crosses the area Tuesday morning.
Expect MVFR ceilings ahead of the front as moisture increases. Brief
periods of visible restrictions may be possible with any passing showers
but confidence is not high enough to include weather in taf forecast. VFR
conditions expected late Tuesday morning through the remainder of the
00z taf period as high pressure builds in from the west.
Outlook...NE flow returns and cloudy conditions with scattered
showers are possible across NE NC on Wednesday in the vicinity of the
front as it slowly pushes south.
no headlines with this forecast package. Hi pressure will slide off the
northern middle Atlantic CST this eveng. A cold front will cross the middle Atlantic
region late tonight through Tuesday morng. NE through southeast winds less than 10 knots
this eveng...will shift to the SW or west Tuesday morng...then shift to
the northwest or north 10 to 15 knots for later Tuesday morng/Tuesday afternoon. An extended
period of NE or east flow will then dominate the waters for Tuesday night
into Sat...as hi pressure builds by to the north of the area and off the New
England CST. Seas will approach and may exceed 5 feet during this