Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wakefield Virginia
1113 am EDT Tuesday Apr 28 2015
high pressure will build into and over the area from the northwest
today into tonight. The high will slide off the coast on
Wednesday...with a low pressure system tracking northeast off the
southeast and middle Atlantic coasts Thursday into Friday.
Near term /until 6 PM this evening/...
late am weather analysis depicts surface high pressure over the upper
Midwest ridging southeast into NC...with a weak trough of low pressure
from southeast New York state into the Delaware-Maryland-Virginia. Clear skies prevail...with the
exception of the Eastern Shore where scattered/broken cumulus has already developed
as another weak shortwave will brush the NE zones into midday. In
general...will have more sunshine than yesterday when skies became
broken/overcast during the late afternoon/early evening...but did bump up cloud
cover to average scattered/broken or broken over the NE zones...while skies average
partly to mostly sunny elsewhere into the afternoon with just scattered cumulus.
Little change need to temperatures...high range from the upper
60s/around 70 f along/west of I-95...to the Lower-Middle 60s near the
Short term /6 PM this evening through Thursday/...
surface hi pressure then weakens and drifts off the CST tonight through Wednesday
morng...maintaining dry weather across the region. Lows tonight ranging from
the middle 40s to lower 50s. Low pressure will then move ewrd across the Gulf
of Mexico Tuesday night...then tracks NE off the SC and NC csts Wednesday through
Thursday. Based on the latest (00z) guidance...and going with a blend
of the ECMWF/GFS...have slowed down and adjusted probability of precipitation for Wednesday afternoon
and Wednesday night. Increasing cloudiness during Wednesday with highs ranging
from the middle 60s to lower 70s. Only have 20% to 30% probability of precipitation moving into
western and southern counties Wednesday afternoon into Wednesday eveng...then 20% to 40%
probability of precipitation Wednesday night. Lows Wednesday night in the upper 40s to lower 50s. Probability of precipitation will
then increase to 50% to 60% on Thursday...as upper trough builds into and over
the area from the northwest...while surface low pressure moves up off the NC CST.
Mostly cloudy to cloudy and cooler on Thursday with highs ranging from
the upper 50s to middle 60s.
Long term /Thursday night through Monday/...
the upper low traverses the Carolinas Thursday night
then pushes well out to sea by late Friday. Showers linger across
the entire area Thursday night...then primarily over eastern areas
Friday morning/midday...before finally ending late Friday afternoon or evening.
Will carry likely probability of precipitation (60%) most areas Thursday night...then solid
chance probability of precipitation (30-40%) on Friday. Dry weather then returns Friday night into
early next week as surface high pressure prevails and an 500 mb ridge builds
over the southeast. Lows generally in the 40s to low 50s Thursday/Friday
nights...warming into middle/upper 50s by next sun/Monday nights. Highs
Friday from the low 60s Eastern Shore to the upper 60s far SW zones.
High temperatures warm by next weekend into the 70s...with low 80s possible
inland next Monday.
Aviation /15z Tuesday through Saturday/...
VFR conditions will persist through the upcoming taf period. High
pressure will ridge into the region from the Midwest Tuesday.
Drier air over the area should keep the sky mostly clear.
Outlook...high pressure will continue to dominate the weather into
Wednesday with dry and VFR conditions to persist through at least
Wednesday evening. A slow moving area of low pressure developing
along the Carolina coast will bring a chance of rain beginning
Thursday morning with a likelihood of sub-VFR conditions and the
chance for some rain rain showers over southern Virginia and NC. Rain and MVFR/local
periods of IFR are forecast Thursday night before ending on Friday.
latest observation reflect northwest flow over the water this morning. Surface low
pressure continues to spin over New England/Atlantic Canada.
Meanwhile, the passage of a quick moving shortwave has allowed
pressure gradient to tighten enough to allow solid Small Craft Advisory across much
of the marine area this morning. Inherited Small Craft Advisory headlines remain in
place for all waters through middle morning, then gradually lower over
the rivers first, then the remainder of the waters by midday. Seas
over the local area have increased to 2-4 feet on the Bay this
morning, with seas building to 3-5 feet on the ocean. Conditions
improve this afternoon through Wednesday night. Pressure gradient slackens enough
to allow quieter/more benign conditions tonight through Wednesday afternoon as
high pressure builds in from the west. However, conditions look to
go downhill once again Wednesday afternoon/night ahead of an area of low
pressure that will move NE and become located along the Carolina
coast Thursday/Thursday aftn, allowing winds to back to the NE and increase
Thursday night. Have slowed down timing slightly and gone with a
blended guidance solution for now with the midweek system as 00z/28
models depicting a weaker, less phased system. Have gone with blended
forecast of wavewatch and current official forecast to depict rising
seas Thursday afternoon/evening into Friday. Expect another period of Small Craft Advisory to be
necessary Thursday aftn/eve.
Marine...Small Craft Advisory until 1 PM EDT this afternoon for