Tornado Warning 10, NWS Baltimore/Washington

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
919 PM EDT Sun Apr 14 2019

.SYNOPSIS...
A strong area of low pressure will move into Great Lakes tonight
as a strong cold front associated with this system passes
through our area tonight into early Monday. High pressure will
gradually build overhead later Monday and Tuesday. A weak
backdoor cold front may move into the area Wednesday before
lifting north as a warm front Thursday. Potentially strong low
pressure and its cold front may impact the area late in the
week.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
Initial round of discrete cells has moved through the area. Some
scattered showers and storms will remain possible the next few
hours, but overall we will be in a lull until the line
stretching through West Virginia reaches us. The 00Z IAD
sounding sampled the environment which contains very strong
shear but limited instability. Even though the storms so far had
a strong disconnect with the lowest levels, the environment
continues to modify due to a strong low level jet and moisture
advection despite it being after dark. Models continue to
indicate CAPE will actually increase the next several hours
ahead of the approaching line. One clue to the overall severity
may be the strength of surface wind gusts. So far they have been
fairly limited, but if they increase, that could be an indicator
strong winds may have an easier time making it to the surface.
Severe level winds have been observed with bowing segments in
West Virginia. Any bulges in the line which orient into a
northeasterly direction could produce a tornado as well (more
favorable orientation to low level shear). It's important not to
let complacency build with the lull the evening and the lack of
severe weather so far...residents should have a way to receive
weather warnings overnight. Would expect the threat to ramp up
between 10-11 PM along the Appalachians, and reach the I-95
corridor around 2-3 AM. It's a little uncertain if the initial
line stays in tact the whole way across, or if it breaks up and
new convection develops in the more favorable environment
near/east of the Blue Ridge.

The other secondary threat will be flooding. There was 1.72"
precipitable water on the IAD sounding. Some areas straddling
the Blue Ridge have already received 1-2 inches of rain with
reports of "nuisance" level flooding. The second round of storms
is expected to be somewhat progressive, with additional amounts
less than an inch. So while some isolated flooding is possible,
am not expecting a widespread threat.

The front will finally push east of the area by daybreak,
bringing a downward trend in activity as winds turn west
northwesterly and drier more stable air filters into the region.
Gusty west to northwest winds will develop behind the cold
front along with upslope rain and snow showers near the
Allegheny Front.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/...
As the cold front pushes off the Delmarva Peninsula Monday
morning, the gradient in its wake will strengthening. This will
deliver strong gusty winds to the area, frequently gusting 35 to
45 mph into the afternoon. Some higher gusts to near 50 mph
will be possible along the higher elevations of the Alleghenies
and Blue Ridge Mountains. A Wind Advisory may be required
tomorrow as a result, but have elected to hold off on issuance
to assess newer model guidance this evening and overnight.

Noticeably cooler conditions will prevail Monday and Monday
night, with temperatures running around 5 degrees below normal
for the middle of April. Dry conditions will persist Tuesday and
Tuesday night as high pressure builds to our south and winds
gradually diminish, and temperatures return to slightly above
normal levels.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
High pressure will continue to be in place over our region through
early Thursday. Winds are expected to remain light and variable
through Thursday with a return southerly flow forming Thursday
afternoon. As the southerly flow forms warm and more moist air is
forecast to be advected into our region starting on Thursday as a
warm front moves to the north of our area. As dew point and air
temps rise ahead of a approaching cold front, convective showers and
thunderstorms will be possible early Friday.

A deep upper level trough is forecast to dig down into Gulf of
Mexico and into the southeastern US states tapping to the warm and
moist Gulf air. A 250 mb jet max is forecast to line up with the
deep upper level trough which will likely enhance the forcing that
occurs ahead of the cold frontal passage. Increasing moisture along
with significant forcing and shear indicates that Friday could be a
concerning day for severe weather. The Storm Prediction Center has
already put our region into a 15 percent chance for the formation of
severe thunderstorms six days out. It is still too early to tell
exact timing of this system and how widespread thunderstorms could
be for Friday. General model trends are suggesting that rain should
be out of our area by Saturday morning. A few linger showers are
forecast for Saturday with high pressure building back into our
region from the south on Sunday.

&&

.AVIATION /01Z MONDAY THROUGH FRIDAY/...
We're in a bit of a break this evening with most showers
skirting around the terminals. Some indications that ceiling
could drop to MVFR, although so far this isn't verifying so far.
Next eyes turn to a line of strong to severe thunderstorms
associated with a cold front that is approaching from West
Virginia. There is some uncertainty if this line stays in tact
or new storms develop/re-develop near and east of the Blue Ridge
Mountains. Storms will be capable of producing brief IFR
conditions, damaging wind gusts, and the threat for an isolated
tornado. Will amend TAFs once specific timing becomes more
evident, with the highest threat window between 03-09Z.

The front will move east of the terminals by 09z, leaving
westerly winds in its wake. Strong gusty winds expected Monday
as the gradient increases, with west northwest winds gusting 30
to 40 knots as a result. High pressure building toward the
region will result in VFR conditions through Tuesday night with
lighter winds prevailing.

Skies will continue to be mostly clear on Wednesday with light and
variable winds. VFR conditions are expected.

On Thursday, winds will become southerly leading to increasing
clouds with some mid to low level clouds possible during the early
parts of Thursday. SubVFR conditions will be possible.

&&

.MARINE...
Southerly winds with SCA conditions will continue until
thunderstorms/squall line/cold front reaches the area late
tonight. Most storms should remain west of the waters until this
organized threat arrives. Strong damaging winds will be
possible with these storms, with a lesser threat of an isolated
waterspout.

This front will move east of the waters by daybreak Monday, as
winds turn out of the west northwest and become quite gusty. A
Gale Warning is in effect for the waters on Monday, and may be
required for portions of the waters Monday evening. Elsewhere,
SCA conditions are expected to prevail over the waters Monday
night. Winds will abate Tuesday and Tuesday night as high
pressure builds toward the region, thus sub SCA conditions are
expected.

Winds will remain light and variable on Wednesday and then become
more southerly on Thursday. Small Craft Advisories may be needed on
Thursday due to stronger winds a loft.

&&

.TIDES/COASTAL FLOODING...
An increasing southerly flow is causing anomalies to rise and
should continue through tonight. Water levels will be close to
minor flooding thresholds around high tide for sensitive areas,
however no flooding is currently forecast.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...Small Craft Advisory until 6 AM EDT Monday for ANZ530>543.
     Gale Warning from 6 AM to 6 PM EDT Monday for ANZ530>543.

&&

SYNOPSIS...BKF
NEAR TERM...ADS
SHORT TERM...BKF
LONG TERM...JMG
AVIATION...ADS/BKF/JMG
MARINE...ADS/BKF/JMG
TIDES/COASTAL FLOODING...BKF

Hazardous Weather Outlook
National Weather Service Baltimore MD/Washington DC
619 PM EDT Sun Apr 14 2019

ANZ530>543-DCZ001-MDZ011-013-014-016>018-508-VAZ052>057-152230-
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-
619 PM EDT Sun Apr 14 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...Tonight

A Tornado Watch is in effect for the entire outlook area until 3
AM. Two rounds of showers and scattered thunderstorms are
expected this evening and overnight. The main severe weather threats
are damaging wind gusts and an isolated tornado. Heavy rain in
thunderstorms may lead to isolated instances of flooding.

.DAYS TWO THROUGH SEVEN...Monday through Saturday

Strong winds with isolated wind damage are possible Monday. Gusts
up to 50 mph are possible, especially in the afternoon and early
evening.

A Gale Warning is in effect for the waters Monday and may need to
be extended into Monday evening.

.SPOTTER INFORMATION STATEMENT...

Spotters activation is requested. Please report severe weather to
the National Weather Service per standard operating procedures.

MDZ003>006-501>507-VAZ025>031-036>040-050-051-501>508-WVZ050>053-
055-501>506-152230-
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-
619 PM EDT Sun Apr 14 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...Tonight

A Tornado Watch is in effect for the entire outlook area until 3
AM. Two rounds of showers and scattered thunderstorms are
expected this evening and overnight. The main severe weather threats
are damaging wind gusts and an isolated tornado. Heavy rain in
thunderstorms may lead to isolated instances of flooding.

.DAYS TWO THROUGH SEVEN...Monday through Saturday

Strong winds with isolated wind damage are possible Monday. Gusts
up to 50 mph are possible, especially in the higher elevations
and across all of western Maryland, eastern West Virginia and
extreme northern Virginia.

.SPOTTER INFORMATION STATEMENT...

Spotters activation is requested. Please report severe weather to
the National Weather Service per standard operating procedures.

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
135 AM EDT MON APR 15 2019

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0126 AM     MARINE TSTM WIND REAGAN NATIONAL ARPT    38.85N  77.03W
04/15/2019  M55 MPH          ARLINGTON          VA   ASOS

&&

EVENT NUMBER LWX1904084

HTS

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
144 AM EDT MON APR 15 2019

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0135 AM     TSTM WND GST     FREDERICKSBURG          38.27N  77.45W
04/15/2019  M63 MPH          SPOTSYLVANIA       VA   AWOS

&&

EVENT NUMBER LWX1904085

HTS

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
153 AM EDT MON APR 15 2019

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0139 AM     TSTM WND GST     1 NE SEAT PLEASANT      38.91N  76.89W
04/15/2019  M62 MPH          PRINCE GEORGES     MD   MESONET

&&

EVENT NUMBER LWX1904086

HTS

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