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Watches, Warnings, and Advisories

As of Mon Aug 21, 2017 11:35:21 EDT

Warnings

There are no active watches, warnings or advisories

Mon Aug 21, 2017 11:35:21 EDT

Hazardous Weather Outlook

As of Mon Aug 21, 2017 10:22:00 EDT

Today And Tonight

Scattered thunderstorms are anticipated this afternoon and evening. These may produce heavy rainfall. A severe thunderstorm with damaging wind gusts and large hail will be possible.

Tuesday Through Sunday

Scattered thunderstorms Tuesday night have the potential to become severe...with damaging wind gusts being the primary threat.

Other

Local spotter activation may be needed this afternoon and evening...and again Tuesday night.

Weather Discussion

As of Mon Aug 21, 2017 10:49:00 EDT

SYNOPSIS

High pressure East of norfolk will move offshore. A disturbance
will bring showers and thunderstorms to parts of our region
this afternoon and evening. High pressure will regain control
overnight tonight through Tuesday, before a strong cold front
pushes across our region and brings another threat for showers
and thunderstorms Tuesday night into Wednesday. The front could
stall to our SouthEast, while a second area of high pressure
builds in from the West later this week.

NEAR TERM /THROUGH TONIGHT/

South winds 5 to 10 mph will usher in low level moisture to
help fuel some showers and thunderstorms this afternoon and
evening. As the high pressure overhead inches offshore today, a
disturbance currently over NorthWest Ohio will make its way
across and just North of the mason-dixon line later this
afternoon and this evening. This disturbance, combined with
increased theta-e and some wind shear should trigger showers
and thunderstorms. The main threats will be damaging winds, some
hail, and very heavy rainfall due to precipitable water values
between 1.80 and 2 inches. Most of this activity will be
confined to an area from us 15 to the chesapeake bay and South
to the fredericksburg. Timing on this activity seems to be
between 3 and 9 pm. Some activity could linger longer until
close to midnight before weakening or dissipating. As rain
activity lessens overnight, some patchy fog could develop in
areas where it has rained and where dewpoint temperatures remain
near 70 or in the lower 70s. Tonight`s lows will be in the
lower to middle 70s.

ECLIPSE

A few eclipse facts...

the sun is about 390 times larger than the moon, and the sun is
farther away from the earth than the moon coincidentally by a factor
of 390. When these align just right the moon blocks the sun`s
photosphere as viewed from earth, and we can see the corona. This is
different each eclipse due to the shape of the magnetic field
emanating from the sun.

the moon is receding away from the earth at a rate of ~4 cm per
year. Eventually total solar ecipses will be impossible.

i`ve heard/read discussion about today`s being a "once in a
lifetime" eclipse. Actually there will be another on april 8,
2024 across the Eastern half of the us. It will stretch from san
antonio, tx to caribou, me. Cities that will experience
totality include dallas, little rock, indianapolis, cleveland,
buffalo, and burlington. Some of these will experience close to
4 minutes of totality.

in 2024 washingon dc will experience 87% coverage (81% today),
baltimore 88% (today 79%).

the jackpot city is paducah, ky. The two eclipse tracks across the
states form somewhat of an "x" with paducah at the center of it.
today it will experience 2:24 of totality. In 2024 the sun will be
covered for 1:45.

enjoy today`s event, observe safely, and see you in 2024.

SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/

A lull in the shower and thunderstorm activity could fulfill most of
Tuesday. High pressure will regain control and allow for dry
conditions. There is a chance for a shower or thunderstorm along the
mason-dixon region and NorthEast Maryland Tuesday afternoon and
evening as a weaker disturbance moves East across pennsylvania.
otherwise, most other places will be dry. Highs will reach the
middle 90s with dewpoint temperatures in the lower to middle 70s
once again. The timing on a strong cold front remains in question
late Tuesday into Tuesday night. We have a chance for showers and
thunderstorms across the Northern and Western half of our region
Tuesday night for now. Tuesday night`s lows will only bottom out in
the middle 70s.

the chance for a couple of showers linger Wednesday in the West,
Central and Southern areas. This is heavily weighted on when the
cold front can pass through the region. High pressure should
gradually build in from the West Wednesday night and bring cooler
and more comfortable conditions to the region. Highs Wednesday will
be middle 80s, cooler than previous days. Lows at night into the
middle to upper 60s.

LONG TERM /THURSDAY THROUGH SUNDAY/

The extended forecast is blissfully quiet as high pressure builds
NorthEast from canada. Not only will the chance for precip be nil,
but temperatures will once again be atypically mild. The only cause
for concern will come from the upper level trough axis dropping
across the NorthEastern us.  This feature may result in added cloud
cover. We shall see if subtleties from associated weak vorticity and
jet energy lead to a swing toward scattered showers in future model
runs.

AVIATION /15Z MONDAY THROUGH FRIDAY/

Vfr conditions through Wednesday night. Any heavy showers or
thunderstorms Monday afternoon and evening, as well as late Tuesday
and Tuesday night could reduce conditions to mvfr or ifr briefly.
winds light and variable becoming South at 5 to 10 knots today.
winds becoming SouthWest around 10 knots tonight through Tuesday,
then backing to the NorthWest at 10 knots Tuesday night and
Wednesday depending on frontal passage.

vfr conditions anticipated thu-fri under building high pressure.

MARINE

No marine hazards expected through Tuesday morning. Have opted
to issue small craft advisory for Tuesday afternoon-evening at
this time; gusts to 20-25 kt anticipated in mixing ahead of
cold front. Behind the cold front at the end of the week, expect
North winds. At this point, speeds look to be less than 15 kt.

LWX WATCHES/WARNINGS/ADVISORIES

Dc...None.
md...None.
va...None.
wv...None.
marine...Small craft advisory from noon to 11 pm edt Tuesday for
     anz530>543.