National Weather Service National Headquarters

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KAKQ 100839
AFDAKQ

AREA FORECAST DISCUSSION
National Weather Service Wakefield VA
339 AM EST Tue Dec 10 2019

.SYNOPSIS...
Low pressure tracks into eastern Canada today with the trailing cold
front crossing the local area this evening. High pressure returns
Wednesday and Thursday. Low pressure develops along the Gulf Coast
Friday before approaching the area this weekend.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
As of 330 AM EST Tuesday...

Latest MSAS show a weak frontal systm nearly stnry ivof the I95
corridor depicting a warmer and more humid airmass to the east
of it with a cooler (wedge like) airmass to the west despite a
sw wind flow. Meanwhile, low pressure is tracking ne ivof Lake
Huron with its trailing cold front extending sw across Ohio/Tn/Ky.

Rather interesting fcst next 24 hrs with rapid changes expected
ranging from near record high temps across the se today to some
minor wet snow accumulations across the nrn most zones Wed morning.

Models not showing much support for pcpn thru 15Z. Given only
mid-high level clouds east of the bndry, expect temps to rise
due to prtl sun. Clouds west of it will keep temps in check today.
Models actually show a narrow band of convective shwrs developing
along the stalled frontal bndry ivof the I95 corridor by 18Z, then
tracking se across the area thru 00Z. While thunder chcs remain
rather low (and not in the grids), would not be surprised to see
an elevated lightning strike as this line punches into the warmer
and more humid airmass across the se later today. Otw, post-frontal
shwrs dvlp with PoPs ramping up by 21Z. Temps tricky and will all
depend on the location of the bndry. A large temp range expected
from highs near 60 ivof LKU to the upr 70s at ECG. Most record highs
today are safe, except for ECG. See CLI section below.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/...
As of 3330 AM EST Tuesday...

The cold front pushes east across the area late aftrn/erly eve. Data
continue to show strong 850-700 mb frontogenesis through the night
as the mid-level trough axis remains to our W. Pcpn type becomes
stratiformed in nature with near 100 PoP for a decent soaking of
rain (QPF 1/3 to 1/2 inch).

As the night wears on, thicknesses crash along with a quick temp
drop. With pcpn continuing past 12Z, expect the rain to become mixed
with wet snow across the nrn third of the fa aftr 09Z. Once again,
this to be an event much like the mid Nov wet snow where pcpn
intensity will determine whether the pcpn can change over to all wet
snow long enuf to drop the temp (33-34 degrees) for a light accum to
occur. Believe this to be the case across nwrn most zones where
accumls of arnd one half inch will be noted. Expect a rain/wet snow
mix as far south as a Cumberland-RIC-XSA-SBY line. Little to no
accumls expected thru the Wed morning commute here as sfc/wet bulb
temps remain above 32. All rain across the south with lows in the
upr 30s-lwr 40s.

Decent lift conts Wed morning before quickly shutting off after 18Z
as drier air to the west pushes the pcpn offshore. Kept likely-cat
PoPs thru 15Z with a mix of rain/wet snow across the nrn most zones.
Rain south. Expect the pcpn to go back to a cold rain by late morn
as intensity becomes lighter and temps slowly inch up. Pcpn ends and
pushes offshore after 18Z. Dcrg aftrn clouds across the west. Not
much rise in temps given the clouds and CAA. Highs Wed low-mid 40s.

A 1040 mb high tracks across Ohio Wed nite / PA Thurs to a psn near
BOX by 00Z Fri. Mstly clr Wed nite with a secondary CAA surge noted.
Lows in the 20s to lwr 30s se. Sunny/cold Thurs. Went below guid for
high temps. Highs upr 30s-lwr 40s except mid 40s sern coastal areas.

Models show the high is slower to push east Thurs nite. This in turn
slows the advancing moisture from the dvlpng systm to the south.
Thus, will indicate increasing clouds by kept it dry thru 12Z Fri
(per latest GFS/ECMWF solns). Lows may occur early then level off
or rise a bit as the clouds come in. Lows upr 20s nw-lwr 40s se.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
As of 330 AM EST Tuesday...

The high is slow to depart Fri while a significant srn stream
systm is progged to dvlp along the Gulf Coast states before
lifting ne along the ern seaboard over the weekend. The 00Z GFS
conts to be the faster model in bringing overrunning pcpn across
the wrn zones Fri morning, while the 00Z ECMWF holds off any
pcpn until after 18Z. Given these changes, made some adjustments
to Fri fcst. Mainly to slow the onset of pcpn down by svrl hrs.
This allows temps to rise above 32 in most areas for mainly a
cold rain. However, did keep a few hr prd of fz rain at the onset
(per thicknesses) across Louisa/Fluvanna county. Otw, rain
overspreads the local area Fri. Highs low-mid 40s across the
Piedmont (insitu-wedge) to 55-60 along the coast.

The wet period extends into the weekend with the GFS and ECMWF
in better agreement. The wettest period look to be from late
Friday into early Saturday. Will increase PoPs from the
south/southwest during the day on Friday but the bulk of the
precip is expected to fall Friday night into early Saturday as
low pressure lifts northward across the region with the models
in agreement. Conditions Sunday look mostly dry with some cloud
cover. High temps on Friday range from the low 40s NW, close to
50 degrees for the Richmond metro, and low to mid 50s for areas
east of I-95. Not looking particularly cold behind the weekend
system either, highs in the 50s Saturday and Sunday with lows in
the upper 30s and low 40s.

&&

.AVIATION /09Z TUESDAY THROUGH SATURDAY/...
As of 1230 AM EST Tuesday...

The local area in btwn systems attm as the first wave of low
pressure moves ne of the area and ahead of the moisture assctd
with the apprchg cold front progged to cross the area this eve.

The low clouds are scouring out due to somewhat drier air and
gusty sw winds behind the departing s/w to the ne. VFR CIGS
already noted across the se with RIC/SBY expected to scour out
the lower stratus during the pre-dawn hours.

Models show the shwrs ahead of the apprchg cold front cross the
area after 18Z with more widespread stratiformed rain expected
behing the fropa after 00Z. Thus, the forecast will show lwrg
CIGS/VSBYS after 00Z along with a wind shift to the north.


OUTLOOK...
A large area of post-frontal light to moderate rain will track
across the area Tuesday night before ending from W to E during
the day on Wednesday. Flight restrictions are likely during this
timeframe. There is a chc that pcpn changes over to PL/SN Wed
AM before ending at SBY, with a slightly lesser chc of PL/SN at
RIC. Not expecting much in the way of impacts from wintry pcpn.
Pcpn should stay in the form of RA at the sern terminals.

High pressure builds into the area Wed/Thurs, allowing VFR/dry
conditions to return. Another area of low pressure brings rain
and degraded flight conditions Friday into Friday night, with
the potential of a brief RA/PL mix during the onset at RIC. Weak
high pressure builds in from the W Saturday.

&&

.MARINE...
As of 330 AM EST Tuesday...

In the near term, existing Small Craft Advisories for the Chesapeake
Bay, Lower James, and Currituck Sound that originally went into this
afternoon have been cancelled. South to southwest flow over cooler
waters (Bay temps in the upper 40s) has made it difficult for many
20 knot+ gusts to mix down to the surface this morning. Cannot rule
out a few gusts to 20 knots at the typical elevated locations, but
do not expect this to be widespread/frequent enough to continue the
existing SCAs. SCAs for the coastal waters have been maintained due
to seas at or above 5 feet.

SW winds continue through the day today, generally in the 10 to 20
knot range. A cold front crosses the waters beginning later this
afternoon, which will turn winds to the NW and then N, and wind
speeds increase into the 15 to 25 knot range with gusts to as high
as 30 knots. These elevated winds will continue into Wednesday
afternoon for portions of the waters as much cooler air filters into
the region. As a result, SCAs are now in effect for the Chesapeake
Bay, Lower James, and Currituck Sound beginning this evening and
continuing into Wednesday. Seas remain elevated through this period,
at or above 5 feet, thus SCAs for the coastal waters have also been
extended to take this in account.

Winds relax Wednesday afternoon, before a reinforcing shot of cold
air arrives later Wednesday night into early Thursday morning as a
strong area of high pressure builds into the region. Winds will once
again increase to 15 to 25 knots, and another round of SCAs will
likely be needed for at least the Chesapeake Bay and lower rivers.
The area of high pressure settles over the region by Thursday
afternoon. Conditions for Friday into Saturday are uncertain from a
timing stand point as the flow turns NE then E as a wave of low
pressure develops over the SE US and lifts into the Mid-Atlantic
States. But would expect SCA conditions with the easterly flow and
likely elevated seas.

&&

.CLIMATE...
Record highs for 12/10:

 RIC...79 in 2007
 ORF...78 in 2007
 SBY...73 in 1966
 ECG...78 in 2007

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...None.
NC...None.
VA...None.
MARINE...Small Craft Advisory from 7 PM this evening to 1 PM EST
     Wednesday for ANZ632-634.
     Small Craft Advisory from 10 PM this evening to 4 PM EST
     Wednesday for ANZ633.
     Small Craft Advisory from 7 PM this evening to 10 AM EST
     Wednesday for ANZ630-631.
     Small Craft Advisory from 10 PM this evening to 10 AM EST
     Wednesday for ANZ638.
     Small Craft Advisory until 4 PM EST Wednesday for ANZ650-652-
     654.
     Small Craft Advisory until 7 AM EST Thursday for ANZ656-658.

&&

$$
SYNOPSIS...MPR
NEAR TERM...MPR
SHORT TERM...MPR
LONG TERM...MPR/JAO
AVIATION...MPR
MARINE...AJB
CLIMATE...MPR