Area Forecast Discussion
Issued by NWS Sterling, VA

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FXUS61 KLWX 210857

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
357 AM EST Thu Feb 21 2019

.SYNOPSIS...High pressure will build to the north of the area
tonight through early Saturday. Low pressure will organize
across the southern Plains Saturday and track northeast toward
the Great Lakes by Sunday pushing a warm front through the area
Saturday night followed by a cold front Sunday afternoon. High
pressure builds again for the first part of next week.



A few rain showers will be possible across southern areas and
also over the Appalachians mtns early this morning before
dissipating as mid-levels dry out. However, low cloud overcast
will likely persist through midday given lack of any significant
wind. Some sunshine will filter in through the clouds in the
afternoon, but high clouds will also start to increase from the
south. Warmer today with highs ranging from the mid to upper 40s
across the north to the low 60s across the south.

The dry period is expected to be relatively short as more rain
is expected to move in again late tonight especially across the
south as warm moist air overruns sfc bdry stalled across the
Carolinas. Unsure on how far north the precip gets, but best
chances appear to be south of I-66 and more so across central
VA. Over the Appalachians, there could be enough cold air for
a little bit of freezing rain/icing.



Off and on rain will likely continue across central VA through
Friday before rain starts spreading northward Fri night as
isentropic lift increases above shallow cool air dome. As high
pressure builds north of the region, sfc temperatures may drop
below freezing late Fri night and Sat morning with light
freezing rain possible mainly north of I-70 and I-68 and across
the Appalachians. Confidence on some ice accumulation across
those areas is beginning to increase and will include in the
HWO this morning. Then, rain becomes more widespread and heavier
Sat afternoon and night as heights aloft begin to fall ahead of
strengthening cyclone across the middle of the country and warm
front begins to advance north. Some flooding is possible due to
combined rain and snowmelt, but overall guidance trended with
significantly less QPF than 12-24 hrs ago. Still time left to
monitor flood potential and wait for better agreement among



Forecast area will be in the warm sector Sunday, with a cold front
crossing the area during the middle of the day. Temperatures at 850
mb likely to reach 12C, which should push highs well into the 60s.
There might be somewhat of a lull to start but the cold front, and
its forcing from its thermal gradient, likely to support additional
showers along with its passage. Winds increase significantly behind
the front...perhaps a bit more on the high-biased GFS, but ECMWF
winds respectable. Sunday afternoon likely to be a windy day, and
Monday will still be breezy until high pressure can finally build.

The ridge will be nearby Monday night into Tuesday (actually
centered over the Great Lakes) with cyclonic curvature still over
New England. The next threat of precipitation will be northern
stream energy, which wouldn`t arrive until Wednesday.



LIFR cigs this morning, improving quickly in the afternoon.
Rain Fri at CHO and all other terminals Fri night through Sat
night with flight restrictions and LLWS likely

Flight restrictions possible Sunday associated with a cold frontal
passage, however do not believe at this time that the would be day-
long restrictions. Winds will be the bigger concern behind the front
(Sunday afternoon into Monday).



Winds 10 kt or less through Sat with winds strengthening late
Sat night into Sunday.

A cold front will cross the waters Sunday. Winds will increase
behind the front. Have high confidence that, at the least, a strong
Small Craft would be required. It`s looking increasingly possible
that Gales could be reached. Strong gusty winds would continue into




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