Scientific Forecaster Discussion

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Area forecast discussion 
National Weather Service Wakefield Virginia
433 am EDT sun Apr 20 2014

Synopsis...
low pressure off the southeast coast...will track slowly northeast
into the Atlantic...as high pressure builds eastward across New
England and off the coast. A cold front will cross the area
Tuesday afternoon into Tuesday night. High pressure returns for
Wednesday and Thursday.

&&

Near term /until 6 PM this evening/...
low pressure off the Georgia/SC CST...will start to drift NE into the Atlantic
during today...as hi pressure builds ewrd across New England. Combination
of that low and surface hi pressure to the north-northeast will result in continued low
level flow from the NE today into tonight. Mainly light rain will also
continue to affect extreme southeast Virginia and NE NC. Likely probability of precipitation across NE NC
cnties near the CST and the Albemarle sand through this morng...with
chance or slight chance over extreme southeast Virginia. Then...chance or slight chance this afternoon
into tonight. Sky ranging from prtly sny north-northwest cnties to cloudy across NE
NC. Maximum temperatures ranging from the upper 50s to middle 60s.

&&

Short term /6 PM this evening through Tuesday/...
upper level ridge builds over the region later tonight through Monday with low pressure
continuing to move out to sea. Improving conds expected over coastal
NE NC (albeit sloly)...with clear to prtly cloudy weather elsewhere.
Cold front tracking into the Ohio Valley Monday eveng...will push east and
over the mountains Tuesday morng. That front will bring increasing cloudiness
from west-east Tuesday...along with the next chance for rain. Most of if not all
precipitation may hold off until afternoon west...and eveng east on Tuesday. Will maintain
a slight chance of a thunderstorm...though dynamics weakening with time...as
the front enters the region. Low temperatures tonight ranging from the upper 30s
to lower 50s. Highs on Monday ranging through the 60s to near 70. Lows Monday
night ranging from the middle 40s to around 50. Hi temperatures on Tuesday ranging from
the middle to upper 70s inland...to the upper 60s to lower 70s at the CST.

&&

Long term /Tuesday night through Saturday/...
near seasonable normal temperatures and dry conditions will highlight
the extended period forecast. A cold front will approach the
region late in the extended period.

Trough axis will align along the middle-Atlantic coast Tuesday night-
Wednesday morning. Additional energy will dive down the backside of the
upper trough (aided by 110+ knots jet streak) Wednesday afternoon...likely
only resulting in middle-level cloudiness. Sprinkles may be possible
over the Eastern Shore. Trough will exit the coast Wednesday afternoon as
diffluence aloft Ushers in surface high pressure. Flow will amplify as
a western Continental U.S. Trough progresses eastward into the plains Thursday. An
associated cold front will reach the Ohio Valley Thursday night-Friday
morning. High pressure will slide over the region Thursday...locating
off the southeast coast Thursday night-Friday. A warm front will lift over
the region Thursday night into Friday...as the cold front reaches the
local area late Friday into Friday night. Spatial and timing differences
exist with respect to frontal timing...as well as the evolution of the upper
flow...so confidence is not high at this time. As a
result...predictability is rather low so have only included
slight chance probability of precipitation Friday night.

Near seasonable daytime temperatures Wednesday and Thursday behind the front in
part to northwesterly flow. Highs generally in the upper 60s to near 70.
Warmer Friday and Sat with SW-west flow...highs in the middle-upper 70s.

&&

Aviation /08z Sunday through Thursday/...
strengthening low pressure off the Florida coast will continue to track
east-northeast off the southeast coast through the taf period, thereby
tightening the pressure gradient over the local area. Meanwhile,
upper level clouds will persist over the forecast area through the afternoon. Drying
high pressure continues to build in from the northwest...helping to keep
precipitation to the south of kecg. Held on to a vcsh group at ecg with
rain showers in the area...but expect predominate conditions to be mainly
dry. Biggest issue today will be west/strong NE flow...gusting to 25-30kt
later this morning through this evening.

Outlook...a cold front will push across the region Tuesday/Tuesday
night...with VFR conds returning Wednesday as high pressure builds into
the region.

&&

Marine...
early morning weather analysis features surface high pressure in place over
northern Maine/southeast Quebec...ridging southward into the mid-Atlantic.
To the south, surface low pressure remains nearly stationary off the
Georgia/Florida coast coast, with an elongated coastal trough extending along
the Carolina coast this morning. The result is continued NE flow
over the waters this morning. Small Craft Advisory flags in place all waters. The surface
low pushes NE along the coastal trough through this evening, west/the
tightening pressure gradient over the waters to bring an increase in
NE winds over the waters. Look for winds to increase to 20 to 25 knots
later this morning through the afternoon, with gusts around 30 knots.
Increasing northeasterly winds will build seas to 6-9 feet...up to 10 feet in the
southern coastal waters.

High pressure will push off the eastern New England coast Sun
night-Mon, as the coastal low slides farther east. As a result,
winds will become more northerly and slowly diminish through Monday afternoon.
Seas will slowly begin to subside...but will remain in Small Craft Advisory range (4-7
ft) through Monday night. Flow backs around to the south Tuesday in
advance of a cold front, set to cross the region Tuesday afternoon-
evening. Seas will likely drop below 5 feet early Tuesday with
speeds falling at or below 15 knots. However...Small Craft Advisory conditions again appear
possible behind the front Tuesday night-weds.

&&

Akq watches/warnings/advisories...
Maryland...none.
NC...none.
Virginia...none.
Marine...Small Craft Advisory until 6 am EDT Monday for anz630>638.
Small Craft Advisory until 6 am EDT Tuesday for anz650-652-654-
656-658.

&&

$$
Synopsis...tmg
near term...tmg
short term...alb/tmg
long term...Sam
aviation...mam
marine...mam