Area Forecast Discussion
Issued by NWS Wakefield, VA-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KAKQ 240024
Area Forecast Discussion
National Weather Service Wakefield VA
824 PM EDT SAT JUL 23 2016
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
.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
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 /01Z SUNDAY THROUGH THURSDAY/...
-- Changed Discussion --A weak cold front over southern Pennsylvania will sink south of SBY
Sunday morning before retreating to the north Sunday evening. High
pressure of the Southeast coast will dominate the weather during
much of the upcoming week. Another weak cold front will graze
northern portions of the area late Tuesday and Wednesday.
VFR conditions will prevail during most of the 00Z TAF period.
Showers and a few thunderstorms were over Maryland and Delaware at
issuance time. These will develop southward and dissipate into
mainly showers during the next few hours. Have VCSH at SBY 01-06z.
Included MVFR fog at SBY and RIC during the overnight hours
despite more bullish hires and MOS products. Even this may be
overdone. Dew points are a bit higher than 24 hours ago but wind and
low level temperatures may prevent fog development.
Southwest winds generally less than 10 knots will prevail on Sunday.
A windshift to the northeast could occur at ORF around midday but
did not include in the TAF. The chances for convection are quite
OUTLOOK...Another mainly dry day is expected Monday. A cold front
drops into the area Tuesday/Wednesday bringing isolated- scattered
showers/tstms both days...primarily during the afternoon/evening
hours. Brief reductions in VSBYS and CIGS to MVFR/IFR levels are
possible with the storms.
-- End Changed Discussion --
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.
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)
NC...Heat Advisory from 11 AM to 8 PM EDT Sunday for NCZ012>017-
VA...Heat Advisory from 11 AM to 8 PM EDT Sunday for VAZ079>082-