Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wakefield Virginia
1000 am EST Thursday Nov 26 2015
high pressure remains centered off the New England coast through
Friday night. A cold front approaches from the northwest late
Saturday...then stalls across the region Saturday night and Sunday.
Near term /through tonight/...
current forecast on track with only minor changes made to grids late
this morning. Middle level cloud deck beginning to mix out over the
Piedmont. Upshot will be a dry and mild Thanksgiving afternoon under
mostly sunny skies. Highs ranging through the 60s.
similar conditions again tonight, with some patchy fog/low stratus
late tonight. Lows mainly in the u30s in the northwest...low to middle 40s
I-95 corridor...and u40s to around 50 southeast.
Short term /Friday through Saturday/...
more of the same Friday...with continued dry and milder weather
expected. Models continue to feature development of a weak trough
just off the southeast coast. Any significant moisture / precipitation prognosticated to stay
southeast of the local area and out over the Gulf Stream. Thus...silent
probability of precipitation (<14%) continue. 850 mb temperatures/thickness tools both support highs
again in the upper 60s to around 70.
00z/26 models even slower with the apprchg cold front. Preferred
GFS/European model (ecmwf) blended solution depicts a weakening boundary sagging
south across the region late Sat into Sat night. Little support for
any measurable precipitation with the actual frontal passage on Saturday, and have
continued to trend down and push back pop...keeping Sat and much
of Sat night dry for most of our area (exception is slight pop
over far northern sections). Have also pushed temperatures upward in
anticipation of some more time in the warm sector for our area on
Sat. Increasing cloudiness should temper highs a bit on Saturday, but
thinking is the uptick in statistical guidance for Saturday is
justified. Bumped maxima up 2-3 degree into the middle to upper 60s
south...but with cooler u50s over the Eastern Shore / Northern Neck.
Long term /Saturday night through Wednesday/...
blocky pattern persists to begin the extended period over the western
Continental U.S....lending to a difficult/low confidence forecast. Stalled
frontal boundary prognosticated to reside west to east across the middle-
Atlantic region sun/Sun night as high pressure builds over the
Great Lakes region. The front will drift slowly southward during the day
sun...with increasing chances for precipitation during the day sun. Front
weakens Sun night...but will maintain chance probability of precipitation over the region.
Surface high pressure builds into New England Monday...ridging southward into
the local area with an in-situ cad wedge. Significant differences
in medium range guidance arise in the middle level flow and resultant
cyclogenesis over the Ohio Valley Monday and Tuesday. Will maintain slight
chance to low end chance probability of precipitation Monday. Have trended forecast toward
the European model (ecmwf) beginning Monday night and Tuesday...which pushes a cold front
through the region late Tuesday into Tuesday night. The result will be chance
probability of precipitation Tuesday and Tuesday night. Drying trend expected thereafter as high
pressure builds eastward from the Midwest.
Temperatures will remain rather steady...near to slightly below seasonal
norms through the extended. Lows generally in the upper 30s to 40s.
Aviation /15z Thursday through Monday/...
a very brief period of shallow fog this morning as areas of frost
burn off and condense over the next 1-2 hours. Otherwise...dry air
over the region will prevent an incoming marine cloud deck from
impacting kecg. Therefore VFR conditions will prevail during the
next 24 hours with a combination of scattered high clouds and fair weather
cumulus around 6 kft above ground level this afternoon...despite persistent onshore
winds at or below 10kt.
A cold front will approach from the northwest late Friday night
and is then expected to slowly stall/weaken over the region
through the weekend. Generally VFR conditions Friday/Friday night with
increasing clouds on Saturday. Predominantly MVFR ceilings possible
with periods of -shra (ifr ceilings possible at times...especially
near coastal taf sites) as the front stalls/weakens over the area.
high pressure remains stacked in place along the eastern Seaboard
today and Friday. Fairly quiet conditions expected on the waters
today with light onshore winds at or below 10-15kt...seas 3-4ft...and
waves 1-2ft. A tighter pressure gradient with stronger resultant
winds over the western Atlantic and a long NE-east fetch will push seas
toward 5 feet early this evening in far southern waters...which will then
build build to 4 to 6 feet late this evening for all coastal zones.
Winds shift around to the north-northwest Friday night as a cold front
approaches from the northwest late Friday night. The front is then
expected to slowly stall/weaken over the region Saturday through
the weekend with periods of light rain showers possible. Winds
maintain a northerly wind direction with speeds at or below 15kt. Seas should
stay elevated at 4-6ft through Saturday due to northerly onshore winds
and then slowly subside to 3-5ft Sat night through at least Sunday
morning as winds become more northwesterly.
Marine...Small Craft Advisory from 10 PM this evening to 7 am EST
Saturday for anz650-652-654-656.
Small Craft Advisory from 4 PM this afternoon to 7 am EST
Saturday for anz658.