Area Forecast Discussion
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FXUS61 KAKQ 222323
Area Forecast Discussion
National Weather Service Wakefield VA
723 PM EDT FRI JUL 22 2016
An upper level ridge prevails over the Mid-Atlantic this weekend
through Monday. A weak front clips the area Saturday night and lifts
back to the north Sunday. A weak cold front drops into the region
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
Current water vapor imagery depicts a trough over the
Northeast US with a broad ridge from the central US through the
Southeast States. At the surface, the pressure pattern is rather
weak, but generally characterized by high pressure across the
Southeast with low pressure over Southeast Canada. Temperatures have
warmed into the upper 80s to low 90s this afternoon with sct
afternoon cu. Dewpoints remain in the low/mid 70s east of I-95, with
areas over the Piedmont only now (as of 20z) mixing down into the
upper 60s. Heat indices average in the mid/upper 90s with a few
locations around 100. Sct convection over the mountains should
dissipate before reaching the local area later this afternoon and
evening due to limited forcing and a lack of deep moisture. A weak
trough slides across the area overnight but this should only bring
passing mid-level clouds. Otherwise, expect warm and humid
conditions with lows in the low to mid 70s.
.SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/...
The upper ridge dampens as it build ewd through the
weekend. 850mb temperatures remain in the 20-22C range (+2 st dev).
The airmass continues to warm Saturday resulting in highs solidly in
the mid 90s inland. Based on todays trends it may be difficult for
dewpoints to mix down and are expected to average in the 70-72 range
during peak heating Saturday afternoon. This results in heat indices
of 100-104 (below the 105 advisory criteria) across the area, and
will be highest (around 104) across se VA and ne NC.
A weak frontal boundary clips the nrn Mid-Atlantic Saturday night. A
30-40% PoP is forecast for the Ern Shore, with a 20% PoP over the
Nrn Neck given some elevated instability and the presence of a
shortwave trough within a NW flow regime. Humid Saturday night with
lows in the mid to potentially upper 70s. The thermal boundary lifts
back to the north Sunday. However, some semblance of a surface
trough lingers over central/se VA/ne NC Sunday. This will result in
highs in the low 90s Sunday over the Ern Shore. However, higher
dewpoints should pool along the old boundary and highs remain in the
mid 90s from inland VA to NE NC. This results in forecast heat
indices in the 100-104 range over interior s-central VA 105-108
values possible over se VA/ne NC. A few tstms are possible in
vicinity of the trough, or along a sea/bay breeze. However, coverage
will be rather limited.
Continued warm and humid Sunday night with lows in the mid/upper
70s. Hot again Monday with highs in the mid 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
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
A cold front crosses the region on Tuesday and then stalls over
the area during the rest of the week...fluctuating/wobbling its
position over time in persistent zonal flow aloft. Temperatures
still expected to peak in the low-mid 90s for highs with dewpoints
in the low-mid 70s. This will generally maintain heat index values
of 100-104 degrees each afternoon. Lows generally in the mid 70s
each night. Precip chances finally increase to a decent 30-40% POP
each afternoon...beginning with the frontal passage on Tuesday
afternoon/evening. Thunderstorms should be expected each day. Main
impacts will be strong wind gusts and locally heavy rainfall due
to pwats upwards of 2.00 inches.
.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
VFR/dry conditions to prevail through Saturday with mainly S/SW
winds around 10 KT. Increased mixing should prevent any fog
development again tonight.
Isolated/scattered tstms possible Sat night at SBY, and then
across southern VA and northeast NC Sun afternoon and evening. A
cold front approaches on Monday and crosses the area on Tuesday
bringing scattered showers and tstms both days...primarily during
the afternoon/evening hours. Brief reductions in VSBYS and CIGS to
MVFR/IFR levels with the storms.
South to southwest winds prevail today through Saturday. Speeds
will ramp up to 15-20kt this evening over much of the bay and
coastal waters...with gusts to around 25 kt occurring between
midnight tonight and 400 AM Saturday morning. Waves/seas will
build to 2-3ft and 3-4ft respectively. Middle sections of the Bay
may see up to 4ft waves during peak wind gusts overnight.
Meanwhile, seas should also build to 4-5ft during this same
timeframe from Cape Charles Light to Fenwick Island. SCA flags
will be in effect for the Bay beginning at 600 PM this evening
through 600 AM Saturday morning...and for all coastal waters from
midnight tonight through 400 AM Saturday morning.
Winds, waves, and seas all diminish around sunrise Saturday
morning. Speeds will be aob 15kt and waves/seas will average 1-2ft
and 2-3ft respectively. A surface trough/boundary drops into the
area on Saturday, which then washes out/dissipates on Sunday.
Winds turn to a more onshore direction by Sunday afternoon with
the seabreeze and speeds average aob 10kt. Another front
approaches from the northwest early next week with winds becoming
more southerly and slightly stronger with speeds aob 15kt.
While its certainly going to be hot Sat-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)
MARINE...Small Craft Advisory until 6 AM EDT Saturday for ANZ630>632-
Small Craft Advisory from midnight tonight to 4 AM EDT
Saturday for ANZ650-652-654-656-658.