Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wakefield Virginia
215 PM EDT Monday Apr 27 2015
high pressure slowly builds back into the area from the west
this afternoon into Tuesday. The high will slide off the coast on
Wednesday...with the next low pressure system tracking along the
southeast coast on Thursday.
Near term /until 6 PM this evening/...
current analysis depicts surface high pressure over the upper
Midwest and surface low pressure off the Canadian Maritimes. Strong
upper low aloft centered off the coast of Maine...but extending
well to the south and west to the lower Great Lakes. WV satellite
shows 2 significant shortwaves of interest...the first already
approaching the County Warning Area is situated over SW Virginia and northwest NC will push off
the NC coast through 18z. The 2nd one lags back to the northwest over
Ohio. Skies have been sunny/mostly sunny thus far...but visible
satellite shows scattered-broken cumulus field developing across northern Virginia and this
will continue to spread southeast into early afternoon. Timing of the 2nd
shortwave diving southeast through the Middle Atlantic States later today is a
bit slower...prognosticated by a model consensus to be over eastern WV and
central Virginia by 00z this evening. Given the dry airmass...this
forcing combined with daytime heating will be the only support for
precipitation. Will scale back on any chances for precipitation until late in
the afternoon/generally after 20z to 21z as the 2nd shortwave approaches
from the northwest (keeping probability of precipitation limited to 20%). Expect skies to become
partly cloudy County Warning Area- wide by early afternoon...possibly mostly cloudy for
a few hours across the north and NE. Highs appear on track...middle to upper
60s most areas...lower 60s on the Eastern Shore.
Short term /6 PM this evening through 6 PM Tuesday/...
short wave exits to the east-southeast this evening...W/ any broken clouds and isolated/scattered
precipitation dissipating overnight. Surface hi pressure to continue to build into region from
the northwest through Tuesday...then weaken/drift off the CST into Wednesday. Low
pressure exiting scntrl Continental U.S. Tuesday/Tuesday night begins to track through the
Gulf CST states on Wednesday...bringing gradual increases in cloudiness/moisture
into the middle Atlantic region. Models continue to hold off most of any significant
precipitation until lt Wednesday. Will maintain will maintain 20-40% probability of precipitation Wednesday
afternoon SW...dry NE.
Low temperatures tonight mainly in the l/m40s. Hi temperatures Tuesday from the m60s at the
CST to u60s-around 70f inland. Low temperatures Tuesday night mainly 45 to 50f. Hi
temperatures Wednesday from the m60s SW to around 70f elsewhere.
Long term /Tuesday night through Sunday/...
the forecast beginning Wednesday night remains weighted
toward the wpc/European model (ecmwf) solution which brings low pressure up the southeast
coast Wednesday night...then deepens the low off the obx on Thursday
before quickly shoving it well out to sea Thursday night. Based on
this solution...will maintain slight chance probability of precipitation (20%) north and chance
probability of precipitation (30-50%) across the south Wednesday night. Will expand chance probability of precipitation
(30-40%) into northern areas on Thursday with high chance to likely
probability of precipitation (50-60%) across southern areas (highest far se)...before
dwindling rain chances from west to east Thursday night as the low
pulls away. The European model (ecmwf) does bring a piece of northern branch energy
south into the forecast area Thursday night which may actually linger precipitation chances
into midday Friday. For now...will cover the possibility with slight
chance probability of precipitation. Dry weather then returns later Friday into next weekend as high
pressure prevails. Lows generally in the 40s to low 50s through the
period. Highs mainly in the 60s Thu/Fri...except some upper 50s
immediate coastal locales. (Normal highs are in the low/middle 70s.)
Highs then warm into the middle/upper 60s at the coast to middle/upper 70s
inland by next weekend.
Aviation /18z Monday through Saturday/...
as of 18z...vsbl satellite showed increasing cloud cover spreading into
the region from the north with bases of 5 to 8k feet. A deep short
wave trough was approaching from the N/NW. Most of this cloudiness
should clear near sunset due to loss of surface heating. North/northwest winds
will prevail through the 18z taf period with winds becoming gusty at
times. 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. A slow moving area of low
pressure will bring a chance of rain beginning Wednesday night with
a likelihood of rain over southern Virginia and NC. Rain is forecast to end
on Friday. Periods of IFR will be possible during this event. Dry
weather returns once again by Saturday.
hi pressure will gradually build in from the west-northwest today through Tuesday...while
strong low pressure over the northern Atlantic slowly moves east. This will result
in stronger northwest or north winds later today into Tuesday afternoon...with Small Craft Advisory
conditions expected on all the waters during this time. Waves
will build to 3-4 feet on the Bay tonight...with seas bldng to 4-5 feet on
the ocean. Calmer conditions expected Tuesday afternoon through Wednesday night...then
another round of Small Craft Advisory conditions will be likely for all waters
Thursday afternoon into Friday morng...as low pressure moves up the CST.
Marine...Small Craft Advisory from 7 PM this evening to 10 am EDT
Tuesday for anz635>638.
Small Craft Advisory until 1 PM EDT Tuesday for anz630>632-634.
Small Craft Advisory from 10 PM this evening to 1 PM EDT
Tuesday for anz633-650-652-654-656-658.