Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

000 
FXUS61 KAKQ 152334
AFDAKQ

AREA FORECAST DISCUSSION
National Weather Service Wakefield VA
634 PM EST Sun Dec 15 2019

.SYNOPSIS...
A slow moving front will become nearly stationary across the area
overnight into Monday. A low pressure system crossing the mid 
Atlantic region Tuesday will drag a cold front across the area 
late Tuesday into early Wednesday.

&&

.NEAR TERM /THROUGH MONDAY/...
As of 230 PM EST Sunday..

This afternoon high pressure is off the SE coast. Meanwhile, a cold 
front is slowly drifting towards our area from the NW and is 
expected to become nearly stationary across our area overnight.
The rest of the day will remain dry however clouds will be on 
the increase tonight. Temps in the mid to upper 50s this 
afternoon will drop to the low to mid 30s north overnight, with 
mid 30s to near 40 south. Some patchy fog is expected early 
Monday morning, especially over southside and inland portions of
NE NC.

&&

.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/...
As of 230 PM EST Sunday...

A tricky forecast for Monday as the position of the nearly 
stationary front will have implications for both precip and 
temperatures. Precip moves in north of the front Monday morning. 
While most of this precip will be rain, there is a chance for some 
mixed precip across far northern portions of the VA piedmont and 
also over the MD eastern shore. QPF amounts will be light and 
surface temps of 33-35 degrees in these areas will likely result in 
little to no accumulation. High temps will be highly variable, with 
low to mid 40s north of wherever the front positions itself, and 
upper 50s to lower 60s south of the front. 

Monday night the front will make a slow progression to the north as 
a warm front. A low pressure system will track from the TN valley to 
the Mid-Atlantic early Tuesday. Temperatures will remain steady or 
climb slightly Monday night into early Tuesday. Low temps Tuesday 
morning range from the lower 40s north to mid 50s south. Rain 
chances increase Tuesday morning ahead of a cold front that will 
cross the western portions of the CWA Tuesday afternoon and exit 
eastern portions of the area by late Tuesday into early Wednesday. 
Rainfall amounts on Tuesday generally in the 0.3 to 0.75 inch range. 
High temps will be mild as the region sits in the warm sector for 
much of the day. Expect upper 50s north to mid and upper 60s south. 

Conditions improve quickly after the frontal passage as high 
pressure builds into the region overnight Tuesday into Wednesday 
morning. Modest CAA and clearing skies should drop temps to the 
lower 20s NW to around 30 SE by Wednesday morning.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
As of 230 PM EST Sunday...

High pressure remains in control Wednesday through Friday. This will 
result in dry weather and slightly below normal temps during this 
period. Low temps Thursday and Friday in the 20s, near 30 at the 
coast, and high temps in the 40s. Overnight model runs had a coastal 
developing over the SE and riding up the Atlantic coast next 
weekend. 12Z runs of the GFS and ECMWF today have a low developing 
over the eastern gulf and then slowly drifting off the SE coast over 
the weekend, while the CMC still tracks the low up the Atlantic 
coast. With the high uncertainty this far out, just went with low 
chance pops for next weekend.

&&

.AVIATION /00Z MONDAY THROUGH FRIDAY/...
As of 115 PM EST Sunday...

VFR conditions are expected through the majority of the 18z TAF
period. RIC and SBY have a chance at briefly reaching MVFR
conditions after 15z Monday due to cloud bases around 2500 feet. W
winds 10-15 kt with gusts to 20 kt will weaken and become light
and variable at around 3 kt overnight. Higher clouds will 
increase by Monday morning and continue through the TAF period.

OUTLOOK...SBY has the potential to see light showers and MVFR
conditions Monday night but otherwise VFR conditions expected
with overcast skies. Tuesday has the potential for degraded 
flight conditions due to low clouds and rain across all 
airports ahead of a cold front which passes through the region 
Tuesday evening. High pressure builds Wednesday with VFR
conditions returning.

&&

.MARINE...
As of 615 PM EST Sunday...

Latest analysis reveals that the pressure gradient has weakened
considerably over the region this evening, with sfc high
pressure centered to our NW progged to move E into the northern
mid-Atlantic overnight. This will force a weak backdoor cold 
front through the region. Have cancelled the one remaining SCA
headline across the northern coastal waters as seas have
subsided to 3-4 ft (with generally 2-3 ft seas elsewhere) and
waves in the Bay only ~1 foot. Expect winds to shift to the NE
over the upper Bay/northern coastal waters after 03Z, spreading
farther south after midnight. Some uptick in wind speeds is
anticipated (to 10-15kt) along with waves in the Bay building to
around 2 ft. 

Much of the 12z/15 model suite seem to be in fair to good 
agreement with respect to handling of winds as the front settles
south over the area Monday, w/low pressure sliding along the 
boundary toward the local area from the mid-south into Monday 
night through Tuesday. Typical minor timing differences remain 
during this period, but in general, ENE wind of 5-10kt is 
expected N of the boundary, with 10-15kt SSW wind to the S of 
the boundary. Seas should be 2-3ft while the boundary is over 
the area, with 1-2ft waves in the Bay. 

By late morning Tuesday into Tue aftn, SW wind could briefly 
increase to 15-20kt for the lower Bay, Currituck Sound and ocean 
zones, which would allow for 3-4ft seas and 2-3ft waves in the lower 
Bay and result in some SCA winds Tue aftn. However, predominate SCA 
conditions not anticipated until the cold front drops across the 
waters Tuesday evening, with modest cold air advection occurring 
Tuesday night with a NNW wind increasing to 20-25kt. A second, 
stronger surge of CAA comes with secondary cold front (and another 
round of CAA) Wednesday night, w/W-NW winds increasing to ~25-30 kt. 
Overall, SCAs are likely for Tuesday night through early Thursday, 
with perhaps a lull during the day Wednesday before secondary surge 
of cold air arrives Wed night. High pressure returns Thursday into 
Friday, with improving boating conditions.

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...None.
NC...None.
VA...None.
MARINE...None.

&&

$$
SYNOPSIS...CMF

National Weather Service Glossary of Abbreviations