Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus61 klwx 151942 

Area forecast discussion
National Weather Service Baltimore Maryland/Washington District of Columbia
242 PM EST sun Dec 15 2019


High pressure will be overhead tonight, then move offshore
Monday. Low pressure will pass south of the area Tuesday and
high pressure will build over the region for the end of the


Near term /through Tuesday night/...

Overrunning precip ahead of a developing low pressure center
over the mid MS valley will spread quickly ewd tonight, first
reaching the appalachian region late this evening and spreading
ewd across the rest area overnight reaching the Chesapeake Bay
by daybreak. Snow will be the main p-type initially across much
of the area except far southern areas like Charlottesville,
Fredericksburg, and southern Maryland where rain will be the main
p-type. There will be a quick burst of snow overnight aided by
wet-bulb cooling and upward vertical motion, then a transition
to a wintry mix around daybreak across north central Maryland and west
of Route 15, and rain east of rt 15 and south of I-70. Areas in
western Maryland are likely to remain below freezing rain through the
day Mon and it is possible they could remain entirely below
freezing through the entire precip event (~ midday tue). Snow
and ice accumulations are expected to be significant and highly
impactful in that area and for this reason a Winter Storm
Warning will be issued for western Allegany and western Mineral.
Please refer to west-southwest and snow/ice maps for more specific details
on snow/ice amounts. Across the rest of the advisory area,
wintry precip should end by midday or early afternoon Monday.

Heaviest precip rates are expected to occur through Monday as
area remains north of the 850 mb warm front, then diminish
somewhat late Monday night as main lift pulls away and area
remains in between 850 mb and sfc fronts. Waves of precip will
continue through midday Tue until cold front clears the area.


Long term /Wednesday through Sunday/...

Cold front will be moving away from our region on Wednesday as a
shortwave trough pushes east into our region. Northwest flow will be
settling over US and temperatures will become below normal. High
pressure will build over our area behind the front and remain in
control through Friday. A southern stream system may affect US by
the weekend.

High temperatures during the long term period will be in the 30s and
40s increasing gradually into the weekend. Low temperatures will be
in the teens and 20s Wednesday night, increasing to the 20s and 30s
into the weekend.


Aviation /19z Sunday through Friday/...

Light snow (except at kcho) developing late tonight with a
transition to sleet, then rain around daybreak except fzra at
kmrb. MVFR conditions late deteriorating to LIFR by midday
Monday. IFR/LIFR cigs through midday Tue in rain/showers.
Conditions improving Tue afternoon with frontal passage but with
strengthening winds.

VFR but breezy conditions are expected Wednesday into Wednesday
night. VFR conditions continue Thursday and Friday.



Small Craft Advisory conditions will be ending quickly with sunset this evening.
Winds should remain below Small Craft Advisory conditions through 06z Tue and
strengthen again late Mon night and Tue. Risk of gales has
diminished for Tuesday.

Breezy conditions on Wednesday into Thursday will need a Small Craft
Advisory. Winds will be receding later on Thursday and remain below
criteria into Friday.


Lwx watches/warnings/advisories...
District of Columbia...none.
Maryland...Winter Storm Warning from 10 PM this evening to 7 PM EST
Monday for mdz501.
Winter Weather Advisory from midnight tonight to 1 PM EST
Monday for mdz003>006-503-505-507.
Winter Weather Advisory from 10 PM this evening to 1 PM EST
Monday for mdz502.
Virginia...Winter Weather Advisory from 11 PM this evening to 1 PM EST
Monday for vaz025-026-503-504-508.
Winter Weather Advisory from midnight tonight to 1 PM EST
Monday for vaz027>031-040-501-505-507.
WV...Winter Storm Warning from 10 PM this evening to 7 PM EST
Monday for wvz503.
Winter Weather Advisory from midnight tonight to 1 PM EST
Monday for wvz052-053.
Winter Weather Advisory from 10 PM this evening to 1 PM EST
Monday for wvz050-051-055-501-502-504>506.
Marine...Small Craft Advisory until 4 PM EST this afternoon for
Small Craft Advisory until 2 PM EST this afternoon for


near term...lfr

National Weather Service Glossary of Abbreviations