Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wakefield Virginia
1026 PM EDT Thursday Oct 8 2015
high pressure to the south of the area moves offshore by Friday
afternoon. Another cold front will approach from the northwest on
Friday...then drop through the region Friday evening into Saturday
morning. Low pressure will develop along or just off the southeast
coast by Sunday and linger into Monday.
Near term /until 6 am Friday morning/...
high pressure remains centered along the southeast coast this
evening into tonight. Meanwhile...the next cold front moves
across the Great Lakes/Midwest...with west-southwest flow aloft increasing
ahead of the front. Expecting a fair to partly cloudy sky tonight
with comfortable low temperatures in the middle/upper 50s (except low 60s
immediate coast). Overnight period expected to remain dry as the
best chances for measurable precipitation will be over the central
Short term /6 am Friday morning through Sunday/...
Friday still looks to be a partly sunny and warm day as a cold front
approaches from the northwest. Highs in the upper 70s to low 80s. Latest
GFS and European model (ecmwf) remain in general agreement with the cold front
pushing through the region Friday evening into Sat morning. Will still have
chance probability of precipitation (25-40%) across north-northwest areas Friday afternoon into early Friday
even...while keeping the forecast dry across the southeast. By Friday night...will
maintain high chance to likely probability of precipitation (50-60%) across much of the area.
Lows will range from the upper 50s northwest to the middle 60s southeast.
For Sat/Sat night...model solutions still diverge a little...
particularly with the handling of an upper low/trough that is
expected to dig across the southeast states to the coast. What has come
into better agreement is the likelihood that Saturday turns out
drier than previously expected. As the upper low/trough digs south
on Sat...it should force the best precipitation chances south into southern
Virginia/NE NC in the morning...and mainly across NE NC in the afternoon.
Will limit slight chance probability of precipitation (20%) to areas along/south of a lku-
occluded frontal passage-mfv line in the morning (dry north)...increasing to likely
probability of precipitation (50-60%) far southern Virginia and NE NC. By afternoon...dry from
fvx-ptb-jgg on north...increasing to likely probability of precipitation down across NE
NC. If current model trends continue...a further reduction in probability of precipitation
north of the Virginia/NC border may be in order on later shifts. Cool
cad setup for Sat will keep maximum temperatures in check...as highs will
range through the 60s.
Generally dry conditions expected Sat night into Sunday with the
upper low lingering along the Georgia/SC coasts. Will maintain some
minimal probability of precipitation for areas along and just north of the Albemarle
Sound. Otw...clouds will be on the decreasing into Sunday. Highs
in the 60s to low 70s.
Long term /Sunday night through Thursday/...
the period begins Sun night with an anomalous cutoff/upper low
centered along or just off the SC/Georgia coast gradually filling and
weakening into an upper level wave off the southeast coast into Monday
night. Latest 12z runs of the GFS/European model (ecmwf) are in better agreement
with this scenario...though some subtle differences in placement
an timing still persist. Will maintain low chance probability of precipitation over the
far southeast zones Sat night through Monday although bulk of support for
precipitation stays south and east of the local area. Highs Monday generally in
the 70-75 f range. Another cold front pushes through the area on
Tuesday...followed by a stronger area of high pressure building in by
Wednesday...and becoming centered south of the area on Thursday. Will carry
just 20% probability of precipitation across the area with the front on Tuesday...then
dry/mostly sunny Wed-Thu. Highs will be seasonable in the 70s with
lows generally ranging from the upper 40s northwest to middle-upper 50s southeast
through the period.
Aviation /03z Friday through Tuesday/...
VFR conditions expected for the majority of the 00z taf period
for the akq taf sites. Weak high pressure slips off the coast
overnight with return flow from the south developing. Enough wind
and cloud cover overnight will limit fog potential. SW winds gusty
at times develops Friday ahead of the next front. Precipitation is expected
to hold off until after 18z.
Outlook...a cold front approaches late Friday and moves across the
region early Saturday. Showers a few thunderstorms are expected late
Friday with showers continuing overnight. Precipitation may continue far southeast
portions Saturday as the front slows its progress off the coast.
High pressure and favorable aviation conditions should prevail
Sunday through Tuesday.
light east/NE flow over the waters late this afternoon with ~1022 mb surface
high pressure centered just off the middle-Atlantic coast. Winds slowly
veer to the south-southeast and increase a bit tonight as the surface high slides
farther offshore. Pressure gradient will tighten during Friday ahead
of a cold front approaching from the northwest. Pressure falls
do not look real impressive...but winds will continue to veer to south-southwest
and increase to around 15kt Bay and rivers/15-20kt across the ocean.
Marginal Small Craft Advisory conditions will be possible...mainly for gusts to 20kt
across the Bay...with seas possibly approaching 5 feet out near 20nm
offshore for the coastal waters north of Parramore Island. However...not
real confident in this scenario given that the waters have cooled
off recently and due to the marginal nature of this event have
decided to not issue any headlines at this time. More significant
will be Post-frontal winds from the north on Sat. Given the time of
year, a period of Small Craft Advisory conditions is likely in the cold air advection
surge...persisting into early Sunday across the Lower Bay and southern
Virginia/NC coastal waters.
Followed a European model (ecmwf)/gefs blend for late in the weekend into early next
week. Expect a gradual return to predominant sub-Small Craft Advisory conditions to
the area for later sun/Monday as cool surface high pressure across the
northeast/mid-Atlc regions, as surface low pressure develops along the
front to the southeast and and slides NE offshore through Tuesday.
Depending on the evolution of southeast upper trough and associated
surface low, winds/seas could remain near low end Small Craft Advisory over southern
coastal zones from late Sunday night and Monday. Due to uncertainty
during this period, have kept them just below for now (nne 15-20kt,
seas 3-4ft). Second, strong cold front crosses by later Tuesday,
with another area of cool high pressure building east from the Tennessee/Ohio