SYNOPSIS
Deep low pressure will move from the Upper MidWest into the
Western Great Lakes tonight. A warm front ahead of the low will
lift through the area late tonight. The cold front will move
into the area Thursday night, then meander nearby through
Saturday before another area of low pressure lifts by Sunday.
High pressure will likely return for the early to middle
portions of next week.
NEAR TERM /UNTIL 7 AM THURSDAY MORNING/
The 00Z KIAD sounding shows a saturated layer remaining around
875-800 mb which has kept a 3,500 to 4,000 foot overcast deck in
place. As low-level moisture underneath the accompanying
inverison intensifies, expect a further lowering of clouds
through the night. This will particularly be the case for those
East of the Blue Ridge Mountains. Some light showers are
possible as this moistening occurs.
A warm front currently near the Virginia/North Carolina border
is forecast to lift Northward tonight. This frontal boundary
should cross through areas South of I-66, while further
progressing Northward on Thursday.
SHORT TERM /7 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/
Warm front will lift North of the area by Thu afternoon with
showers and t-storms becoming increasingly likely across
Northern and Western areas as cold front approaches. Some severe
t-storms are possible due to strong effective shear and
sufficient destabilization (i.E temps in the mid 70s and
dewpoints in the low to mid 60s). Cold front will enter the fcst
area Thu evening with showers/t-storms continuining along and on
the North side of the bdry into Fri morning. The front will
continue to push South into Southern VA and NC Fri night with
the threat of thunderstorms focused mainly South of I-66.
LONG TERM /SATURDAY THROUGH WEDNESDAY/
A low pressure system will move across the Great Lakes region
Saturday. An associated warm front, extending SouthEastward into the
mid-Atlantic region, will move NorthEastward throughout the day into
Saturday evening. Some rain shower activity is expected across the
Mason-Dixon region and portions of the Chesapeake Bay region.
Temperatures will be quite warm in the mountains, the Shenandoah
Valley and along the Potomac River zones where the warm front pushes
well to the North. Temperatures in Central and NorthEast Maryland
and Northern portions of the Chesapeake Bay will be 10 to 15 degrees
cooler and only a few degrees above average where the warm front
will struggle to lift NorthEastward or not make it at all Saturday
into Saturday night. In terms of temperature numbers, we could be
looking at highs in the lower to middle 80s in the SouthWest, while
highs only make it to the lower to middle 60s in the
NorthEastern zones.
As for the day Sunday into Sunday night, the warm air continues to
push North across the region behind the warm front and causes our
high temperatures to reach the upper 70s to middle 80s from the
Shenandoah Valley to NorthEast Maryland and the Chesapeake Bay area.
An approaching cold front, attached to the aforementioned low
pressure over the Great Lakes, will push through the region from
NorthWest to SouthEast Sunday into Sunday night. Widespread shower
and some thunderstorm activity will develop ahead of and along the
cold front. A few thunderstorms could be strong with strong winds
and hail. As the front clears respective areas, temperatures will be
cooler where there is cloud cover, showers and thunderstorms. Highs
in the mountains and Western Maryland and East-Central West Virginia
may only reach the middle 60s to lower 70s. Temperatures Sunday
night will take a dive from the readings experienced Saturday night.
They will be noticeably colder. Lows ranging from the middle 30s in
higher mountains in the West to the middle 50s in the SouthEast
zones.
There could be a few lingering rain showers in Southern Maryland
early Monday. Otherwise, drier and colder air will filter in due to
building high pressure from the NorthWest for a brief period of time.
During the same time frame, a mix of rain and snow showers could
develop over the Appalachians during the day Monday into Monday
night. It is too early to say how much snow could accumulate but it
looks like a small amount and could be confine to the highest
elevations of Western Maryland and Eastern West Virginia.
The upslope rain and snow showers could transition to all snow
showers at higher elevations in the same regions and accumulations
could be small through the day Tuesday. Tuesday will be the coldest
day of the extended forecast with highs in the lower to middle 30s
in the mountains to the middle 50s in Southern Maryland.
AVIATION /02Z THURSDAY THROUGH MONDAY/
Increasing low-level moisture tonight with IFR cig restrictions
expected. Showers possible overnight into Thu morning West of
I-95. Showers and t-storms become more numerous Thu afternoon
and evening as cdfnt enters the area. Continued cloudy and
showery Fri with cig restrictions.
MVFR conditions possible at MRB, MTN and BWI with nearby rain
showers Saturday into Saturday evening. Elsewhere will be VFR
conditions. Winds SouthEast becoming South 5 to 10 knots gusts 15
knots. MVFR to IFR conditions possible at all terminals with showers
and thunderstorms Sunday into Sunday evening. Winds SouthWest
becoming NorthWest 10 to 15 knots gusts 20 knots.
MARINE
SCA conditions will continue through Fri morning before
diminishing Fri afternoon. SMWs may be required Thu afternoon
and night, particularly across the Northern waters and Fri
afternoon and night across the Southern waters.
Small craft advisories possible Saturday night for the main stem
Chesapeake Bay and Tidal Potomac. Winds SouthEast to South 10 to 15
knots gusts up to 20 knots. Small craft advisories likely Sunday
into Sunday evening. Winds SouthWest becoming NorthWest late 10 to
20 knots gusts 25 knots late.
TIDES/COASTAL FLOODING
As high pressure shifts offshore on Thursday, tidal anamolies are
expected to rise due to Southerly winds. Sensitive tidal locations
such as Baltimore, Annapolis, and Havre De Grace will reach action
stage Thursday morning.
LWX WATCHES/WARNINGS/ADVISORIES
DC...None.
MD...Small Craft Advisory until 6 PM EDT Thursday for MDZ008.
VA...None.
WV...None.
MARINE...Small Craft Advisory until 6 PM EDT Thursday for ANZ530>543.
