Area Forecast Discussion
Issued by NWS Wakefield, VA

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FXUS61 KAKQ 232008
AFDAKQ

Area Forecast Discussion
National Weather Service Wakefield VA
408 PM EDT SAT JUL 23 2016

.SYNOPSIS...
An upper level ridge prevails over the Mid-Atlantic region through
Monday. A weak front clips the northern Delmarva tonight, then lifts
back to the north Sunday. A weak cold front approaches from the
north Tuesday and drops into the region Tuesday night into
Wednesday.

&&

.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
The current surface analysis depicts high pressure
centered from the mid-South to the wrn Atlantic with a lee-side
trough east of the mountains. Aloft, a ridge is centered over the
Mississippi Valley region with a trough over Atlantic Canada, and
and embedded shortwave trough dropping across NY. Sct convection is
beginning to develop ahead of this feature over PA. Locally, hot and
humid conditions are occurring with temperatures in the low/mid 90s,
with dewpoints in the low/mid 70s. Heat indices average 100-104 at
most reliable sites. However, there are a few ASOS sites in sern/ern
VA/ne NC indicating heat indices of 105-106. Not enough to warrant a
short-term heat advisory. Nevertheless, use caution with outdoor
activities this afternoon and early evening.

The shortwave trough and associated weak frontal boundary will
continue to drop se and clip the nrn Mid-Atlantic/Delmarva this
evening. A few stronger storms are possible given a belt of 30-40kt
of effective shear combined with MLCAPE values progged to remain
1000-1500 J/kg through the evening. The primary threat with any
storms is strong wind gusts. A 30-40% PoP is forecast for the Ern
Shore, with a 20% PoP over the Nrn Neck. Humid tonight with lows in
the mid/upper 70s.

&&

.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
The upper ridge dampens as it builds ewd Sunday and
Monday. 850mb temperatures remain in the 20-22C range (+2 st dev).
The airmass continues to warm Sunday (S of the retreating boundary)
and Monday across the entire area. Highs Sunday should reach the
mid/upper 90s. Based on todays trends it may be difficult for
dewpoints to drop below the low/mid 70s Sunday s of the boundary,
and especially across se VA/ne NC. Given this, heat indices should
range from 105-108 there and a Heat Advisory has been issued. Heat
indices should average 100-104 from the Piedmont to the RIC metro to
the Nrn Neck and VA Ern Shore, with slightly lower values over the
Lower MD Ern Shore in closer proximity to the boundary.

Continued warm and humid Sunday night with lows in the mid/upper
70s. Hot again Monday with highs in the mid/upper 90s. At this time
dewpoints are forecast to remain in the low/mid 70s during peak
heating and this could push heat indices into the 105 to 108 range
across much of the region. There is a minimal chc of late afternoon
tstms over the nw Piedmont counties. Otherwise, dry conditions are
expected.

The upper ridge begins to slowly break down Monday night into
Tuesday. Remaining warm and humid Monday night with lows in the
low/mid 70s. Continued hot Tuesday with highs in the mid 90s.
Dewpoints remain in the 70s with heat indices ranging from around
100 nw to 105-108 possible across the se. There is a 20-30% chc of
afternoon tstms mainly across the nw counties.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
Stacked high pressure over the Southeast Coast allows
zonal/westerly flow aloft to settle across the region Tuesday
night through the week. A series of wx disturbances will pass
across the region and keep a chance for thunderstorms in the
forecast each aftn/evening. Pwats around 2.00-2.25 inches and
dewpoints in the low-mid 70s will result in muggy conditions with
ample moisture present across the area...making strong gusty winds
and locally heavy rainfall the anticipated impacts from
thunderstorms. Combine the humidity with temperatures remaining in
the low 90s, and heat indices will continue to run around
100-104 degrees with a few pockets in far SE VA/NE NC reaching
105-106 degrees for an hour or two each aftn. Lows generally in
the low-mid 70s inland and mid-upper 70s beaches each night.

&&

.AVIATION /20Z SATURDAY THROUGH THURSDAY/...
VFR conditions and light winds prevail this afternoon at all
terminals. This will continue through the 18Z TAF period and
probably beyond. Winds will generally be 10 kts or less, and out
of the S/SW, although onshore flow should persists through the
afternoon at KORF. Still the potential for a shwr/tstm later this
evening/tonight at KSBY, as a weakening front drops into the
area. However, enough uncertainty persists, and latest hi-res
models have backed off on the potential, to include in the TAF.

A cold front drops into the area Tuesday/Wednesday bringing
isolated- scattered shwrs/tstms both days...primarily during the
afternoon/evening hours. Brief reductions in VSBYS and CIGS to
MVFR/IFR levels are possible with the storms.

&&

.MARINE...
Generally quiet/benign conditions expected into early next week.
Winds generally s-sw aob 15kt tonight through Monday.
Zonal/westerly flow aloft settles across the region Tuesday
through the rest of the week. A series of weather disturbances
will pass across the region and keep a chance for thunderstorms in
the forecast each aftn/evening. There may be a surge in sw winds
to 15kt Bay/Sound and 15-20kt Monday night ahead of the
approaching weather, however SCA flags are not anticipated at the
moment. Seas average 2-3ft and may surge to 3-4ft Monday night.
Waves average 1-2ft and may surge to 2-3ft Monday night.

&&

.CLIMATE...
While its certainly going to be hot today thru Mon, climatologically
this is the hottest time of the year with several heat waves having
occurred in the past that have been far more intense than what we
will experience. Record highs are unlikely to be set and in most
cases, doubt they will even challenged within 5 degrees.

* RECORD HIGHS:

*     Sat (7/23)    Sun (7/24)   Mon (7/25)

* RIC: 103 (1952)   105 (2010)   105 (2010)
* ORF: 103 (2011)   105 (2010)   105 (2010)
* SBY: 103 (2011)   101 (2010)   100 (2010)
* ECG: 104 (1952)    97 (2012)    99 (1949)

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...None.
NC...Heat Advisory from 11 AM to 8 PM EDT Sunday for NCZ012>017-
     030>032.
VA...Heat Advisory from 11 AM to 8 PM EDT Sunday for VAZ079>082-
     087>090-092-093-095>098-514-523>525.
MARINE...None.

&&

$$
SYNOPSIS...MPR
NEAR TERM...AJZ
SHORT TERM...AJZ/MPR
LONG TERM...BMD
AVIATION...MAS/WRS
MARINE...BMD
CLIMATE...


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