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Area forecast discussion 
National Weather Service Wakefield Virginia
148 am EDT Monday Mar 30 2015

Synopsis...
a weak cold front moves across the area Monday morning. High
pressure returns Monday afternoon and night. Low pressure tracks
across the northern middle Atlantic Tuesday with the associated cold
front dropping through the region Tuesday night.

&&

Near term /through today/...
models underestimating the dry air over the forecast area as temperatures since
sunset have crashed to near or below forecasted mins over the eastern half
of forecast area where the clouds have yet to increase. Have lowered mins
over eastern areas...with lows occurring over the next few hours. Lows
u20s-m30s with steady or slowly rising readings aftr midnite.

Quick look at the Erly 00z data suggests some precipitation drys up/dspts
as it moves east of mts tonight. Appears best chances for precipitation ahead
of the apprchg cold front will be aftr 09z an over the northern third
of the forecast area. Thus...adjusted probability of precipitation a bit with highest probability of precipitation (40%) over
the northern most counties west of the Bay with 20-30 pop elsewhere xcpt
remaining dry through 12z across southeastern coastal areas. Any precipitation expeceted to
be in liquid form...although some ice pellets possible at the onset over the
north due to the dry lower levels.

The surface front exits the coast Monday afternoon...bringing an end to precipitation
at the southeast coast and a wind shift to westerly winds. Winds will average
10-15 miles per hour with gusts of 20-25 miles per hour. The breezy downsloping wind
conditions will help to boost temperatures into the lower 60s with
upper 50s at the immediate coast.

&&

Short term /tonight through Wednesday/...
weak surface ridging...northwesterly flow aloft and some weak shortwave energy
crossing the region Monday night will result in some passing high
clouds overnight Monday night. Lows will be around seasonal normals
with readings in the upper 30s to lower 40s. For Tuesday...a fast
moving low pressure system driven by zonal flow aloft tracks
across the northern middle Atlantic Tuesday afternoon. Expect mostly sunny
conditions to begin the day with increasing clouds across the
north as the day progresses. A ribbon of 20-30% probability of precipitation (for -shra)
has been maintained for primarily the northern interior Virginia counties and
the Maryland lower Eastern Shore for Tuesday afternoon/evening as low pressure
crosses the northern middle Atlantic region. It will be difficult to get
any precipitation S of the low track with deep layered west-southwest flow. Low level
thickness values support highs approaching 70f on Tuesday over
interior Virginia/NE NC. This is certainly possible with low pressure
tracking north of the region...resulting in deep layered west-southwest flow.
Expect highs in the upper 60s over the aforementioned areas...with
lower 60s over the Maryland/Virginia Eastern Shore...and locally cooler values
along the immediate Atlantic coast. Low pressure exits the
Delaware-Maryland-Virginia after midnight Tuesday night...followed by high pressure on
Wednesday. Lows will range from the low-middle 40s north of Interstate 64
to middle-upper 40s south of Interstate 64. A slight cool down
anticipated for Wednesday with high pressure building in and light northerly
winds. Highs should range from 65 SW to 55 NE.

&&

Long term /Wednesday night through Sunday/...
split flow continues to be problematic during the extended
period...but models continue to come into better agreement with a
late week frontal passage. To begin the extended...high pressure
pressure slides offshore Wednesday night. Increasing southerly flow on the back
side of the departing high and a flattening southern stream wave will
push a warm front through the local area Thursday. Resultant warm air advection will push
temperatures into the low 70s inland and low-upper 60s Eastern Shore and
coastal areas. Model consensus is to keep Thursday frontal passage dry
thanks to limited moisture and a lack of appreciable forcing. Have
removed slight chance probability of precipitation over the Piedmont Thursday. Potent northern
stream wave locates over the Great Lakes region Thursday night-Friday
pushing an associated/deepening surface low into southeast Canada. Attendant
cold front prognosticated to reach the central Appalachians during the late
Thursday-Friday timeframe. GFS continues to be less amplified with the northern
stream system...pushing the front through the region around 12 hour
quicker than the more amplified/slower European model (ecmwf). Regardless of spatial
and timing differences...expect increasing chances for precipitation
beginning Thursday night and continuing through Sat. 28/12z European model (ecmwf) pushes
the precipitation offshore Friday night...but the GFS stalls the front over
the region through Sat. Have maintained slight chance to low end
chance probability of precipitation Sat to account for uncertainty. Mild temperatures expected
Thursday night behind the warm front...with temperatures generally in the low-
middle 50s. Warm sector/southwesterly flow pushes temperatures into the middle 70s inland
(possibly warmer depending on cloud cover) and upper 60s-low 70s Eastern
Shore and coastal areas. Cooler Sat with highs middle 60s inland and
upper 50s-low 60s Eastern Shore and coastal areas. High pressure prognosticated
to build over the southeast states Sat night-sun...with decreasing chances
for precipitation.

&&

Aviation /06z Monday through Friday/...
center of surface hi pressure has shifted off the southeast coast as of
06z. This has allowed winds to shift to the SW. A weak cold front
will cross the area today... bringing a chance for showers mainly
across the southeastern half of the area after daybreak this morning. All
shower activity is expected to end by the afternoon. Winds will shift
to the northwest behind the front before quickly backing to west/SW by tonight.

High pressure builds back into the southeast US Tuesday but a cold front
moving through the area may bring a few showers to ksby Tuesday
evening. Wednesday/Wednesday night will be dry as high pressure builds in from
the north.

&&

Marine...
high pressure has centered over eastern SC this afternoon...extending
northward over the local water. The result is sub-Small Craft Advisory conditions...with
northwesterly winds at or below 15 knots...waves 1-2 feet and seas 3-4 feet. Surface ridge axis
pushes offshore this evening with winds becoming south-southwesterly tonight. The
next cold front approaches from the northwest tonight...crossing the water
late Monday. Gradient winds increase aloft late tonight-Monday
morning...but warm air advection over cold water will result in a sharp low level
inversion. Models continue to indicate SW winds of 15-20 knots over the
Bay and 20-25 knots over the coastal waters late tonight-early Monday
morning...but do not anticipate higher velocity winds aloft to mix
to the water due to aforementioned inversion. Have capped speeds at
15 knots in the Bay and 20 knots coastal waters. Have also undercut
wavewatch due to GFS winds being too strong. Local studies also
suggest brief S-southwesterly fetch will have troubles building seas to 5 feet
in the northern waters. As a result...no Small Craft Advisory headlines are planned at this time.
Small Craft Advisory conditions also not anticipated Post frontal Monday night due to
weak gradient winds and limited cold air advection. High pressure briefly builds
over the waters Monday night-Tuesday morning with the flow switching from
the northwest back to the SW Tuesday. Low pressure and an attendant cold front
approach the water Tuesday...crossing the water Tuesday night. Small Craft Advisory
conditions are possible Post frontal Tuesday night-Wednesday morning. High
pressure returns to the water weds-thurs...resulting in sub-Small Craft Advisory
conditions.

&&

Akq watches/warnings/advisories...
Maryland...none.
NC...none.
Virginia...none.
Marine...none.

&&

$$
Synopsis...bmd/mpr
near term...bmd/mpr
short term...ajz/bmd/jao
long term...Sam
aviation...jdm/mas/dap
marine...Sam
climate...

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