Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wakefield Virginia
934 PM EDT Tuesday Mar 31 2015
low pressure moves off the Virginia coast tonight. High pressure
will build over the area on Wednesday...and gradually shift off
the coast on Thursday. The next cold front approaches from the
northwest on Friday...and crosses the region Friday night into
Near term /until 6 am Wednesday morning/...
appears the rap is best handling on what has occurred over the
past few hours. Moisture continues to increase along the trailing cold
front as it is crossing the Piedmont late this evening with even some
lightning strikes since 00z. Meanwhile...center of the low now apprchg
the lower ches Bay near windmill pt. Have bumbed up probability of precipitation for the
rest of the evening west of the Bay with likely to categorical
continuing along the Eastern Shore. Added slght chance thunder to southern Virginia counties
as well. Added a few hours of probability of precipitation to the enr shore through 06z where
showers prognosticated to linger. Winds quickly shift to the north-northwest behind the
departing low over the marine area. Gusts up to 30 kts are possible
once this occurs.
A gust to 48kts at 827 PM resulted in a mini "heat burst" at ric
as the tmp jumped from 73 to 79 degrees.
Conds dry out quickly after 06z with skies becoming mostly clear.
Low temperatures mainly in the upper 30s to middle 40s.
Short term /6 am Wednesday morning through Friday/...
Canadian high pressure returns to the region on Wednesday. A cooler day
under mostly sunny skies should be anticipated with highs in the
Lower-Middle 60s for interior southern Virginia/NE NC and in the middle- upper 50s
closer to the coast as winds turn onshore in the afternoon as the
pressure gradient weakens. Surface high pressure axis shifts offshore
late Wednesday night. Light winds and mostly clear skies should result
in overnight lows in the middle 30s to around 40 most locations.
With surface high pressure axis offshore on Thursday and a weather
disturbance approaching the region from the SW...the area will be
within a warming airmass especially as breezy south winds develop
by the afternoon. Most inland locations should reach the lower 70s once
again under mostly sunny skies...with highs in the middle- upper 60s
at the immediate coast. Increasing clouds Thursday night as upper ridge
axis shifts off the coast and a more moist SW flow aloft develops.
In general...models are slower at bringing in deep moisture and
the northern stream and southern stream are slower to phase. Have scaled
back a bit on probability of precipitation for Friday...looks like a low end chance for mainly
-ra Friday morning...primarily across northern zones as low level moisture
overspreads the region. Very mild Thursday night in south-southwest flow and
incraesing clouds...lows in the 50s to possible as warm as 60 f in
a few spots. Warm/variably cloudy Friday with 20-30% chance for -shra
and perhaps some late day thunderstorms as the surface front moves closer to
the region. Highs mainly in the middle-upper 70s...possibly close to
80f if enough sun can prevail. Main rain event looks to hold off
until Friday night described in the long term below...
Long term /Friday night through Tuesday/...
extended period will start off wet as a cold front crosses the
region Friday night-Sat morning. Still some minor spatial and timing
differences in the models with respect to associated southern stream energy and the
cold front...but mostly now with how quick precipitation clears the coast
Sat. Have increased probability of precipitation to likely Friday night...except the southeast. Theta-
east advection and mild temperatures will result in marginal instability Friday
evening. Soundings also indicate sharpening lapse rates as temperatures
aloft cool. Will introduce slight chance thunder Friday evening. Cold
front exits the coast Sat as the parent low and shortwave energy
lift into the NE states/Canadian Maritimes. High pressure builds in
from the west late Sat...remaining over the region through sun. The
result will be dry conditions with a mostly sunny sky and slightly
below normal temperatures. Highs Sat-sun generally in the low 60s inland
and middle-upper 50s Eastern Shore and coastal areas. Lows Sat night in the
upper 30s to low 40s. Broad upper trough will remain over southeastern
Canada through the weekend into early next week. Associated backdoor
front will remain north of the region. High pressure pushes offshore
sun as return flow begins to moderate temperatures. Moisture from
the Gulf begins to spread back northward into the Midwest early next week
as weak perturbations in the westerly flow cross the region. Begin to
reintroduce slight chance-low end chance probability of precipitation Tuesday-Tuesday night. Highs
Monday in the middle-upper 60s inland and upper 50s to low 60s Eastern Shore
and coastal areas. Lows Monday night in the upper 40s-low 50s. Highs
Tuesday in the low 70s inland and middle-upper 60s Eastern Shore and coastal
Aviation /02z Wednesday through Sunday/...
low pressure over eastern Virginia associated with a southward
movement cold front will move off the coast this evening. Winds
shift to northwest during the first several hours of the taf period and
become gusty toward the coast. A few showers will accompany the
front mainly over northern portions. Showers continue for a few more
hours at sby. The sky clears quickly overnight. North winds continue
on Wednesday as high pressure builds over the area.
Outlook...high pressure moves off to the south as the next cold
front approaches from the northwest. Showers are expected Friday night
ahead of the frontal passage Saturday morning. Dry weather returns
for the rest of the weekend.
low pressure has located over northern Virginia this afternoon with a trailing
cold front located along the Ohio Valley. Strong gradient over the
region between low pressure and high pressure off the Florida coast has
resulted in strong SW winds over the water this afternoon. Speeds
generally 15-25 knots. Few gusts of 30 knots observed on elevated sites
closet to land...where 30 knots gusts also observed. Seas generally 2-3
feet and waves 1-3 feet. Seas build to 3-5 feet northern waters this evening.
Low pressure pushes offshore this evening with the cold front
sweeping across the water around midnight. Brief lull in Small Craft Advisory speeds
expected this evening in advance of the front...but a northwest cold air advection surge
expected Post frontal. Speeds increase to 20-25 knots with a few gusts
up to 30 knots after midnight. Seas build to 4-5 feet all coastal zones
with waves 3-4 feet. Small Craft Advisory conditions will be relatively short lived as
high pressure quickly builds over the waters Wednesday morning. Southeast swell
may keep seas hovering around 5 feet 20 nm out through Wednesday morning...but
subsiding Wednesday afternoon. High pressure slides offshore Wednesday night
with flow returning to the S at or below 15 knots. Southerly winds increase Thursday as
a cold front approaches from the west. Marginal Small Craft Advisory conditions are
possible late Thursday-Thursday evening with southerly winds around 15-20 knots.
Seas in the northern waters also prognosticated to reach 5 feet. Flow becomes SW
Friday as the front hangs up along the central Appalachians. Front
finally crosses the waters late Friday night. Brief period of Small Craft Advisory
conditions expected Sat morning before high pressure builds in
from the west. High pressure remains over the water through the
Marine...Small Craft Advisory until 10 am EDT Wednesday for anz630>638.
Small Craft Advisory until noon EDT Wednesday for anz650-652-
Small Craft Advisory from 4 am to noon EDT Wednesday for