Scientific Forecaster Discussion
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Area forecast discussion
National Weather Service Wakefield Virginia
358 am EDT Mon Sep 23 2019
surface high pressure pushes farther offshore of the mid-Atlantic
coast today. A weak cold front will push across the area tonight,
with high pressure rebuilding over the area Tuesday through
Near term /through tonight/...
as of 330 am EDT Monday...
Latest upper air analysis shows a well defined shortwave
tracking eastward near Lake Superior, with ridging across the
deep south. At the surface, an elongated area of high pressure
was positioned west-southwest-east-northeast from ern SC to well off the Virginia/NC coast.
There was an area of developing low pressure just to the east
of the aforementioned upper trough, with an associated cold
front extending NE-SW from srn qc to central Illinois. Clear skies
prevail across our area, with temperatures in the mid-upper 60s
in srn Virginia/NE NC. It is still in the low 70s early this morning
across most of the northwest half of the County Warning Area. The aforementioned upper
trough is progged to track from Lake Superior to on/qc, as the
cold front approaches the area from the northwest. Another very
warm/hot day is in store today W/ 5-15 kt SW winds and mostly
sunny skies. Low-level thicknesses will be similar to yesterday,
but dew points will be slightly lower by aftn (upper 50s west of
I-95), so have slightly higher Max temperatures across the area.
Forecast highs range from the upper 80s-around 90 near the
coast, with low 90s inland. Cannot rule out mid 90s in a few
locations in central Virginia.
00z/23 guidance continues to be slightly slower with the
approaching front. Expect the front to cross the mountains
early this evening, which will result in mostly cloudy skies
across the Piedmont by 00z Tue. The (weakening) front is progged
to cross the area from northwest to southeast tonight. There is a slight chc
of a shower across the northwest Piedmont after sunset. The best upper
level dynamics will stay well to our north as the front crosses the
County Warning Area. In addition, dew points will be lower when compared to our
typical Summer fropas (leading to marginal instability at best).
Therefore, have confined any mention of thunder to the Virginia nrn
neck/Maryland ern shore (from 03-06z). Have maintained 20-30%
pops...highest north/NE (for mainly showers). Best timing for
showers looks to be 03z- 9z Tue. There could be a lingering
shower or two near the Atlantic coast of Virginia through 12z Tue. Quantitative precipitation forecast
amounts look to be a few hundredths of an inch at best. Kept
pops aob 14% for south central Virginia into interior NE NC. Lows
tonight range from the low 60s northwest to the upper 60s southeast.
Short term /Tuesday through Wednesday night/...
as of 330 am EDT Monday...
The front should move south and east of the County Warning Area by 15z Tue.
Behind the front, expect clearing skies and northwest winds. As a
result, Tue will be mostly sunny (w/ a bit more cloudiness
across the southeast during the morning) and not warm nor as humid with
northwest winds ahead of weak sfc high pressure building east through the
Ohio Valley. Highs mainly between 80-84f. Clear skies and light
winds expected 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 Sunday/...
as of 255 PM EDT Sunday...
Strong sub-tropical ridge looks to persist through the period.
This will result in (continued) dry wx and temperatures
remaining aoa normal through the latter half of the week. With
high pressure offshore, return flow continues on Thu. There is a
small chance for showers with a weakening front approaching by
later Thu/early Fri...but chances of accumulating pcpn are quite
low and pops have accordingly been held under 14%.
Highs Wed in the u70s/l80s east to mid 80s inland...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/Sat. Lows in the l-m60s
Wed night and M-u60s for the remainder of the period.
Aviation /08z Monday through Friday/...
as of 135 am EDT Sunday...
VFR conditions expected through the 06z taf period. Skies will
be mainly clear through this morning/midday before few-scattered cumulus
develop late in the day ahead of an approaching cold front.
S-SW winds will mainly be in the 5-10 kt range through the
remainder of the overnight before increasing to 10-15 kt during
the day today. A few gusts of 15-20 kt are possible this aftn.
The aforementioned cold front crosses the area tonight-early Tue
am. Expect broken ceilings of 5-8k feet with the frontal passage along with a
small chc of shras. The highest chc (~30%) will be at sby from
03-09z Tue, with a 15-20% chc of pcpn at ric/phf/orf. Shras are
expected to be light-moderate, with a very low chc of brief MVFR
vsbys. Skies clear from northwest to southeast early Tue am behind the front.
SW winds diminish to 5-10 kt tonight before becoming northwest at
around 10 kt on Tue (with a few higher gusts possible near the
Outlook...VFR/dry conditions expected Tue-Thu as high pressure
builds into the area before another dry cold front crosses the
region late Thursday into early Friday.
as of 345 am EDT Monday...
Sfc high pressure continues to move farther offshore early this
morning as low pressure and an associated cold front move east
across the Great Lakes. Winds have been elevated over the past
12 hrs in the increasing pressure gradient between these 2
features and generally avg around 15kt from the SW. Seas are 3-4
ft north and 2-3 ft S with waves in the Bay 2-3 ft. Not quite enough
to warrant any headlines in the Bay and with daytime heating
later this aftn expect winds to remain about where they are now
given 90+ air temperatures over water temps in the mid 70s. Small Craft Advisory
headlines remain in effect for coastal waters north of Parramore
Island today/tonight due to primarily for seas building to 4-5
ft (though south-southwest winds will increase to 15-20 kt and a few gusts
to 25 kt will be possible as well).
The cold front will move in from the northwest later tonight/early Tue
morning and we may see winds increase slightly over the Lower
Bay late this evening from the SW but again this looks too
short-lived to issue any headlines at this time. More likely, we
may need a short-fused Small Craft Advisory headline for the Bay Tue morning in
the wake of the front as winds shift to the north-northwest and deeper
mixing develops with a drier/cooler airmass moving in from the
north. Given that this still looks marginal, and mainly a 3rd period
event, did not raise any headlines in the Bay W/ this forecast
package. Winds should then decrease to north/northwest ~10 kt by Tue aftn.
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 would
anticipate that additional headlines will be needed for the
coastal waters during this timeframe. This will also make for a
high rip current threat 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 week.
as of 345 am EDT Monday...
Not expecting record highs to be set today but given very warm
temperatures have included the records here for reference:
* record highs today (9/23):
* richmond: 98 (2005)
* norfolk: 100 (1895)
* salisbury: 98 (1914)
* eliz city: 95 (1980)
Marine...Small Craft Advisory from 10 am this morning to 5 am EDT
Tuesday for anz650-652.