textproduct: Baltimore/Washington

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.