Scientific Forecaster Discussion
fxus61 kakq 231958
Area forecast discussion
National Weather Service Wakefield Virginia
358 PM EDT Mon Sep 23 2019
a weak cold front will push across the area late tonight, with
high pressure rebuilding over the area Tuesday through midweek.
Near term /until 6 am Tuesday morning/...
as of 330 PM EDT Monday...
Latest upper air analysis shows a well-defined shortwave
tracking across the upper Great Lakes into the interior
northeast. This feature has served to dampen downstream ridging
across the deep south. Meanwhile at the surface, a pre-frontal
trough was noted from the western Carolinas up into the northern
mid-Atlantic (e PA/west md). Weak low pressure just to the east of
the aforementioned upper trough continues to slide slowly north-NE
over southeast qc/northern New England, with the associated weakening
surface cold front extending NE- SW from sern qc into west PA/east Ohio
down into the mid-south. Continued very warm/hot temperatures
across the local area, with 19z temperatures into the lower 90s
well inland, with temperatures in the 80s along coastal
communities from Ocean City to Currituck. Look for late aftn
temperatures to "welcome" the autumnal equinox to top out in
the low to mid 90s inland...mid to upper 80s along the coast.
Given current location of the front...have nudged timing even a
few hours slower into the late evening/overnight, which meshes
well with 12z cams. This will result in a partly to mostly
cloudy sky across the Piedmont by mid- evening, with increasing
clouds late and int the overnight hours over the Northern Neck
and Eastern Shore. 20-30% pops continue coincident with the
frontal passage late this evening...with low pops owing to dry
antecedent airmass and weak forcing over the local area. Kept
pops aob 14% for south central Virginia into interior NE NC (or mainly
I-64 and S-sw).
Upper level dynamics stay well to our north as the front crosses
the County Warning Area. In addition, quasi-zonal flow aloft and aforementioned
dry antecedent conditions have combined to yield dewpoints that
are lower relative to our typical Summer fropas (leading to
marginal instability at best). Therefore, have confined any
mention of thunder to the Virginia Northern Neck/Maryland ern shore (from
03-06z...11p-2a edt). Best timing for showers looks to be in
that same period from around midnight into predawn hours early
Tue. There could be a lingering shower or two near the Atlantic
coast of Virginia through 12z Tue.
Unfortunately, while much of the area could use some appreciable
rainfall, quantitative precipitation forecast amounts look to be meager...on the order of a few
hundredths of an inch at best. Early morning lows tonight range
from the low 60s northwest to the upper 60s southeast.
Short term /6 am Tuesday morning through Wednesday night/...
as of 330 PM EDT Monday...
The front will drop south-southeast of the local area by mid-late morning
Tuesday. Expect quick clearing and briefly breezy northwest winds Post-
frontal. As a result, Tue will average out mostly sunny (w/ a
bit more cloudiness across the southeast during the morning). Not quite
as warm, nor as humid, as weak sfc high pressure builds east
toward the area from the Ohio Valley. Highs Tuesday in the low to
Clear sky/light winds will provide good radiating conditions
Tue night, as the high becomes centered just west of the County Warning Area.
Cooler with lows in the 53-58f range inland/low 60s near the
immediate coast. The area of weak high pressure moves just
offshore of the Carolina coast by Wed evening. Winds turn back
to the S-southeast by late Wed. Still mostly sunny/less humid on Wed
with highs in the low-mid 80s. Slightly warmer Wed night (w/ a
light south breeze). Lows mainly in the low-mid 60s.
Long term /Thursday through Monday/...
as of 155 PM EDT Monday...
Strong sub-tropical ridge still looks to persist through the
forecast period. This will result in (continued) dry wx and
temperatures remaining aoa normal through the latter half of
the week into next weekend. With high pressure offshore, return
flow resumes on Thu, with temperatures ticking up slightly for
the late week period into the weekend.
Highs mainly 85-90f Thu...in the l80s at the coast and m80s
inland then from 80-85f at the coast to the M-u80s inland
Fri. Highs in the upper 80s to around 90 both sun/Mon. Early
morning lows in the l-m60s Wed night and M-u60s for the
remainder of the period.
Aviation /20z Monday through Saturday/...
as of 200 PM EDT Monday...
VFR conditions expected through the 18z taf period. Noticing
some increasing cumulus/SC to the west ahead of an approaching weak
cold front. S-SW winds will mainly be in the 10-15 kt range this
aftn, with a few gusts to ~15kt are possible this aftn. The
aforementioned cold front crosses the area late tonight- early
Tue am. Expect broken ceilings of 5-8k feet with the frontal passage along with a
small chc of shras, mainly at sby...though a brief rain showers possible
for all sites except kecg.
Outlook: sky quickly clear from northwest to southeast after 10z/6a Tue am
behind the front. SW winds diminish to 5-10 kt before becoming
northwest at around 10 kt by mid-morning Tue (with some higher gusts
possible coastal terminals). VFR/dry conditions expected Tuesday
afternoon through late this week, as high pressure builds into
the area, then offshore late Wednesday. Another dry cold front
drops across the region late Thursday into early Friday.
as of 350 PM EDT Monday...
Late this aftn, sfc high pressure continues to move farther
out to sea as a cold front approaches from the west-northwest. Winds were
south-southwest 5-15 kt with gusts to near 20 kt over the nrn coastal
waters. Seas were 3-5 ft north and 2-3 ft S with waves in the Bay
The cold front will move in from the west-northwest later tonight into Tue
morning, with south-southwest winds shifting to the north-northwest over the waters.
Have issued a short-fused Small Craft Advisory headline for the entire ches Bay
from 4 am until 1 PM Tue in the wake of the front, as north-northwest
increase to 15-20 kt due to deeper mixing as a drier/cooler
airmass filters in from the north. Have also issued a Small Craft Advisory for the
srn two coastal waters from 10 am Tue to 10 am Wed, as northerly
winds 15-20 kt build seas to 4-5 ft in those areas. Winds will
then decrease to north/northwest ~10 kt by late Tue over the waters. Another
concern mainly after the winds diminish Tue aftn will be increasing
swell from tropical cyclone Jerry (well offshore but making its
closest approach late Tue/wed). Wavewatch keeps seas ~4 ft but
nwps depicts seas of 5-6 ft. Generally splitting the difference
here yields some 5 ft seas Tue night/Wed, so have kept sca's for
the coastal zns until 10 am Wed. This will also make for the
possibility of a high rip current threat for Tue/Wed as well.
Winds will remain light and variable Wed, as the sfc high moves
slowly off our coast, then turn to the S Wed night and Thu with
another front approaching the area once again at the end of the
as of 1145 am EDT Monday...
Not expecting record highs to be set this aftn but given very
warm temperatures, have included the records here for
* record highs today (9/23):
* richmond: 98 (2005)
* norfolk: 100 (1895)
* salisbury: 98 (1914)
* eliz city: 95 (1980)
Marine...Small Craft Advisory from 4 am to 1 PM EDT Tuesday for
Small Craft Advisory until 10 am EDT Wednesday for anz650-652-
Small Craft Advisory from 10 am Tuesday to 10 am EDT Wednesday