Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wakefield Virginia
1244 PM EDT Friday Jul 31 2015
a cold front will move off the coast this morning. High pressure
builds over the area later this morning into Saturday. A weak
cold front crosses the region Saturday afternoon into Sunday
morning...before high pressure returns to start next week.
Near term /until 6 PM this evening/...
early this morng...cold front was pushing through NE NC with scattered
showers and isolated thunderstorms along and behind the front over southeast Virginia into
NE NC. The front will move southeast and off the CST during today...with
hi pressure and drier air building in from the west-northwest. The humidity will be
lower (more comfortable) across just about the entire region...except
far southeast Virginia and NE NC...where this area will be closest to the
exiting frontal boundary. As a result...will maintain a 20% pop
over these counties into this eveng. Highs in the upper 80s to lower
90s...except middle 80s at the CST.
Short term /6 PM this evening through Sunday/...
tonight and Saturday...
hi pressure will remain over the area for dry weather and a mostly clear
to partly cloudy sky. Humidity levels start to increase a little
on Sat. Lows tonight in the 60s to lower 70s. Highs on Sat in the lower
90s...except middle to upper 80s at the CST.
Saturday night and Sunday...
a weak cold front is now shown to move across the area Sat afternoon into
sun morng. What remains to be seen is whether or not it can
muster up enough moisture to produce a few showers as it passes.
For now...have left the forecast dry...as models not all that
convinced that it will. Mainly clear to partly cloudy with lows
Sat night in the 60s to lower 70s. Remaining dry most places on
sun...as hi pressure rebounds. There's a mainly slight (20%) chance of
isolated showers across the far southeast with a weak coastal boundary still in
place. Highs on sun in the upper 80s to lower 90s...except middle 80s
at the CST.
Long term /Sunday night through Thursday/...
pattern begins with a middle/upper level ridge centered over the SW
Continental U.S. And an upper level low near Hudson Bay Canada. GFS/European model (ecmwf)
are in good agreement with this overall setup into Tuesday...but then
diverge quite a bit Wed/Thu...the operational GFS being much
stronger/pushing farther south with the upper trough than the
European model (ecmwf) (or the GFS ensemble means). Typical summertime temperatures
can be expected Monday with highs mainly ranging from the middle
80s/around 90 f along the coast to the lower 90s inland. Generally
looks dry although will maintain a 20-30% pop in NE NC due to
potential seabreeze. For Tue-Wed...fairly confident in hot weather for
Tuesday...as both models have rising 800 mb temperatures and a west/SW flow in low
levels. Will maintain a 20% pop due mainly to a weak cap with 500 mb
heights only 585-588 dm. Highs mainly in the middle 90s inland and
90-95 f at the coast. Less confidence for Wed/Thu...GFS would
suggest much cooler conds...while the European model (ecmwf) would support highs in
the middle 90s to perhaps 100 f. While the European model (ecmwf)/wpc pattern will
generally be favored (cold front to our north until Thursday aftn)...think
the drier/hotter weather will ultimately not be as hot as predicted due
to antecedent wet/humid conditions of the past month. For now will
show a slight cooling with highs Wednesday 90-95 f and Thursday upper 80s to
lower 90s. Dew points are forecast by models to mix out into the low
60s west of I-95 through the period...generally stayed a little higher
than this...middle 60s west to lower 70s east. For now this yields heat
indices staying below 105 f next week. As for probability of precipitation...will only
have ~20% probability of precipitation Wednesday...rising to 30% most areas Thursday west/ the approach
of the cold front from the north.
Aviation /18z Friday through Wednesday/...
VFR cndtns through the forecast prd as high prs builds in from the northwest.
Scattered cumulus dspts by 00z with sky clear thereafter. North-NE winds around 10 kts
this afternoon become light / variable tonight.
Outlook...dry weather prevails through the weekend. A slight chance of
thunderstorms is in the forecast Sunday night through Tuesday...with best
chances confined to southeastern portions.
winds have shifted to the north/NE all areas with speeds averaging
10-15 knots. Front weakens across eastern NC/south-southeast of the local area this
afternoon and tonight. Coastal waters forecast will carry predominate
10-15 knots (15 knots far northern ches bay) in the Bay this morning. Waves
in the Bay average 2-3 feet before diminishing this afternoon and tonight.
Seas average 2-4 feet...are steady/slowly falling north...but rising
across the south.
Winds turn back to the south-southeast and veer to the south-southwest
for later tonight and Sat...and remain light (aob 10 kt) as the front
weakens just to our south-southeast along the Carolina coast. Winds briefly
veer offshore (w-nw) early Sunday as another weak front drops
across the area...with winds quickly turning back to the east-southeast sun
aftn/eve...and south-southwest Monday/Tue, as surface high pressure becomes anchored
over the western Atlantic. Waves Sat into next week average 1-2 feet in
the Bay with seas 2-4 feet.
have raised moderate risk for rips Virginia Beach and NC Outer Banks as
~15 knots north-northeast/onshore wind is bringing 3 feet nearshore seas to the
surf zone. This...combined with a falling tide prevailing through
middle afternoon should yield strengthening rips. (Low tide does not occur
until around 2 pm).
Water levels will continue to trend downward today as flow has
turned north-northeast. Anomalies may rise again with evening high tide cycle
Saturday night on southerly (channeling) flow up the Bay ahead of
another weak cold front. As with yesterday, tidal anomalies
looking to be on the order of around one half to three quarters of
a foot above normal at Bishops Head/Cambridge could yield some
spotty nuisance flooding...but still expected to fall shy of minor