Tornado and Damaging Winds in Maryland, May 23, 2019

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
246 PM EDT Thu May 23 2019

.SYNOPSIS...
A cold front will approach from the north through this evening
before passing through overnight into early Friday. High
pressure will briefly build overhead later Friday through Friday
night before moving offshore Saturday. A weak cold front will
stall out nearby for Sunday and Monday, and a Bermuda high may
cause hot and humid conditions during the middle portion of next
week.

&&

.NEAR TERM /THROUGH TONIGHT/...
A Severe Thunderstorm Watch is in effect until 8 PM this evening
for much of northern Virginia, central and southern Maryland,
and eastern West Virginia.

A south to southwest flow has caused a return of noticeably
warmer and more humid conditions this afternoon. Latest
mesoanalysis shows around 1000-2000 J/KG of MLCAPE developing
ahead of a line of showers and thunderstorms. The line of
showers and thunderstorms is expected to pass through the
Washington and Baltimore Metropolitan areas between 3 and 5 pm
this afternoon, and then across southern Maryland into central
Virginia later this afternoon into early this evening. Deep
layer shear remains quite strong (around 45-50 knots ahead of
the line). The combination of the instability and strong shear
suggests that severe thunderstorms are possible with damaging
winds and large hail being the primary threats. The best chance
for severe storms are most likely near and east of the Blue
Ridge Mountains across northern Virginia into the Virginia
Piedmont as well as the Washington and Baltimore Metropolitan
areas/southern Maryland. These areas are east of a pressure
trough, and somewhat higher dewpoints has allowed for the higher
instability. An isolated tornado cannot be ruled out due to the
strong shear as well.

The cold front will drop into the area from the north this
evening before slowly moving through our area into central
Virginia overnight. Scattered showers and thunderstorms may
accompany the frontal passage later this evening, and with
strong shear in place there is a threat for severe
thunderstorms. However, confidence is lower due to the loss of
daytime heating. Convection should dissipate overnight as the
front drops farther south and drier air begins to filter in from
the northwest.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
The cold front will continue to drop south Friday and weak high
pressure will build overhead later Friday into Friday night.
Warm conditions will continue, but it will turn out breezy and
noticeably less humid behind the boundary.

High pressure will move offshore Saturday and a return southerly
flow will usher in a return of more humid conditions. A few
showers and thunderstorms are possible in the afternoon and
evening, especially west of the Blue Ridge Mountains where
instability will be higher and there will be a pressure trough
that acts as of lifting mechanism.

Warm and humid conditions are expected Saturday night due to a
southwest flow around high pressure offshore.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
Sunday will be a very warm and potentially unstable day, with a
cold front dropping toward the region. Timing will be key, as
there is the potential for another active afternoon/evening if
the front drops south of the MD/PA border overlapping with any
daytime heating.

Present indications suggest that the boundary could sag south of
the area Monday, but the ridge will intensify Tuesday-
Wednesday. If that holds true, the middle of next week will be
very warm if not hot. However, anticipate model fluctuations on
these details. This would also impact thunderstorm chances,
which at this point don't look very high.

&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
A line of showers and thunderstorms will likely pass through the
terminals this afternoon, between 19 and 21z. The best chance
for thunderstorms will be across KIAD, KBWI, KMTN, and KDCA.
Locally damaging wind gusts and large hail are possible.

A cold front will pass through the terminals tonight. Another
round of scattered showers and thunderstorms are possible late
this evening, but confidence is lower due to the loss of daytime
heating. VFR conditions are expected most of the time Friday
through Saturday. Northwest winds will gust around 20 knots
Friday before diminishing Friday evening. Winds will turn to
the south for Saturday.

The only apparent flight restrictions at this time would be within
showers/thunderstorms. Sunday afternoon-evening seems to be the
best opportunity.

&&

.MARINE...
A line of showers and thunderstorms will likely pass through the
waters late this afternoon into early this evening. Damaging
winds and large hail are possible, and a waterspout cannot be
ruled out. Storms are most likely to pass through between 4 PM
and 7 PM this afternoon and early evening.

Another round of showers and gusty thunderstorms are possible
later this evening, but confidence is lower due to the loss of
daytime heating.

A Small Craft Advisory is in effect for the waters until
midnight. There may be a brief lull in the stronger gradient
winds overnight before winds increase behind a cold front
Friday. A Small Craft Advisory is in effect for the waters
Friday into Friday evening. High pressure will briefly build
overhead Friday night before moving offshore Saturday.

Thunderstorms may be affecting the waters late Sunday, with
northwest flow conducive for Small Craft Advisories behind the
front, lingering into Monday.

&&

.TIDES/COASTAL FLOODING...
Elevated water levels are expected through this evening due to a
southerly flow, but confidence is too low for an advisory due to
a westerly component to the wind and the fact that the next high
tide will be the lower of the two this evening.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...Small Craft Advisory until midnight EDT tonight for ANZ530>543.
     Small Craft Advisory from 7 AM to 8 PM EDT Friday for
     ANZ530>543.

&&

SYNOPSIS...BJL
NEAR TERM...BJL
SHORT TERM...BJL
LONG TERM...HTS
AVIATION...BJL/HTS
MARINE...BJL/HTS
TIDES/COASTAL FLOODING...BJL

Hazardous Weather Outlook
National Weather Service Baltimore MD/Washington DC
104 PM EDT Thu May 23 2019

ANZ530>543-DCZ001-MDZ011-013-014-016>018-508-VAZ052>057-241000-
Chesapeake Bay north of Pooles Island MD-
Chesapeake Bay from Pooles Island to Sandy Point MD-
Chesapeake Bay from Sandy Point to North Beach MD-
Chesapeake Bay from North Beach to Drum Point MD-
Chesapeake Bay from Drum Point MD to Smith Point VA-
Tidal Potomac from Key Bridge to Indian Head MD-
Tidal Potomac from Indian Head to Cobb Island MD-
Tidal Potomac from Cobb Island MD to Smith Point VA-
Patapsco River including Baltimore Harbor-
Chester River to Queenstown MD-Eastern Bay-
Choptank River to Cambridge MD and the Little Choptank River-
Patuxent River to Broomes Island MD-
Tangier Sound and the inland waters surrounding Bloodsworth
Island-District of Columbia-Southern Baltimore-Prince Georges-
Anne Arundel-Charles-St. Marys-Calvert-Southeast Harford-
Prince William/Manassas/Manassas Park-Fairfax-
Arlington/Falls Church/Alexandria-Stafford-Spotsylvania-
King George-
104 PM EDT Thu May 23 2019

This Hazardous Weather Outlook is for the Maryland portion of the
Chesapeake Bay, Tidal Potomac River, and adjacent counties in
central Maryland and northern Virginia as well as the District of
Columbia.

.DAY ONE...This Afternoon and Tonight

A Severe Thunderstorm Watch is in effect until 8 pm this evening.
Isolated to scattered severe thunderstorms are possible this
afternoon and evening. Locally damaging winds and large hail are
the primary threats, but an isolated tornado cannot be ruled out
as well.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed this afternoon and evening.

MDZ003>006-501>507-VAZ025>031-036>040-050-051-501>508-WVZ050>053-
055-501>506-241000-
Washington-Frederick MD-Carroll-Northern Baltimore-
Extreme Western Allegany-Central and Eastern Allegany-
Northwest Montgomery-Central and Southeast Montgomery-
Northwest Howard-Central and Southeast Howard-Northwest Harford-
Augusta-Rockingham-Shenandoah-Frederick VA-Page-Warren-Clarke-
Nelson-Albemarle-Greene-Madison-Rappahannock-Orange-Culpeper-
Northern Fauquier-Southern Fauquier-Western Highland-
Eastern Highland-Western Loudoun-Eastern Loudoun-
Northern Virginia Blue Ridge-Central Virginia Blue Ridge-
Hampshire-Morgan-Berkeley-Jefferson-Hardy-Western Grant-
Eastern Grant-Western Mineral-Eastern Mineral-Western Pendleton-
Eastern Pendleton-
104 PM EDT Thu May 23 2019

This Hazardous Weather Outlook is for eastern West Virginia,
northern and central Virginia, and central and western Maryland
with the exception of Garrett County.

.DAY ONE...This Afternoon and Tonight

A Severe Thunderstorm Watch is in effect until 8 PM this evening
for portions of northern and central Virginia, central Maryland,
and the eastern Panhandle of West Virginia. Isolated to scattered
severe thunderstorms are possible this afternoon and evening.
Locally damaging winds and large hail are the primary threats, but
an isolated tornado cannot be ruled out as well.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed this afternoon and evening.