Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wakefield Virginia
957 PM EST sun Nov 29 2015
a backdoor cold front will stall across the Carolinas overnight.
A series of low pressure systems will track along the boundary
through Tuesday. The next cold front crosses the area Wednesday.
Near term /until 6 am Monday morning/...
backdoor cold front has continued to settle farther S through eastern NC this
evening. Widespread ceilings at or below 1kft found over the forecast area (exception being
over portions of the lower Maryland/Virginia Eastern Shore. A damp and cooler
evening...W/ spotty -ra/-l...an area of -ra spreading east along-S of the
Virginia-NC border at this time west/ a larger area beginning to enter southern WV/SW Virginia
heading east. Highest probability of precipitation (60-100%) central/southern areas of Virginia into NE
NC...W/ slight chance in vicinity of lower Maryland Eastern Shore. Added -l to -ra forecast. Low
temperatures from 40 extreme northwest and far interior lower Maryland Eastern Shore to around
50 southeastern coastal areas...l50s ob beaches.
Short term /6 am Monday morning through Wednesday/...
a complex weather pattern through this period as a series of low prs systms
track across the region keeping a rthr soggy forecast through Wednesday before a
cold front sweeps everything offshore late Wednesday.
First short wave tracks along the stalled frontal boundary across NC Monday before
that energy spawns a coastal low east of cape hat Monday night. Categorical
probability of precipitation will be maintained across the southern two thirds of the forecast area Monday
morning. Data suggests a lull in the steady precipitation Monday afternoon as the
energy transfers towards the coast. Xpctn being the western Piedmont
where moisture from the next short wave apprchs. A raw day across the northwest
Piedmont with little in the way of tmp rise. Temperatures steady in the l-40s
west of the i95 corridor but range to the l-m50s along the coast.
Coastal low tracks slowly NE across the vacapes Monday night and Tuesday
while the energy from the next short wave tracks NE along The Spine of the
mts. Likely probability of precipitation will be maintained Monday night (rain/drizzle) despite
the forecast area between the two weather systms. Wedge holds tight across the Piedmont
with lows from near 40 northwest to l50s southeast. Best lift / overrunning precipitation
prognosticated across northern half of forecast area Tuesday from that next short wave so have kept
the Cat to high likely probability of precipitation going then. Wedge begins to break down
allowing temperatures to rise a bit. Highs from near 50 northwest to near 60 southeast.
Still plnty support for likely probability of precipitation across the northwestern half of the forecast area
Tuesday night ahead of apprchg cold front. Models are showing a dry
punch coming up from coastal NC into southeastern Virginia Tuesday night...thus only
chance probability of precipitation there. Lows u40s-m50s.
Cold front slowly crosses the forecast area Wednesday. Anthr short wave prognosticated to track NE
along it will likely enhance threshold rainfall potential. Given the
possiblity for a triple point low track...decent lift and increasing precipitable waters...
some lclly heavy downpours will be possible. Kept precipitation type stratiformed
for now...but some convective elements may occur if current trends hold.
Highs Wednesday in the u50s-m60s.
Quantitative precipitation forecast totals starting tonight through Tuesday expeceted to average 1/2 to 3/4 in.
Anthr 1/2 inch to 1 inch possible with the precipitation along and ahead of the
Long term /Wednesday night through Sunday/...
leaning closer to the 12z GFS for the extended period. Cold front
will push off the CST Wednesday night...with lingering probability of precipitation alng and right
behind the front into early Thursday morng. Will maintain a dry forecast
for Thursday through sun...as a large area of hi pressure will build eastward and
eventually over the area from the plains and Midwest. Lows in the upper
30s to middle 40s Thursday morng...and mainly in the 30s to lower 40s
Friday...Sat and sun morngs. Highs mainly in the lower to middle 50s
Thursday...Friday and Sat...and in the middle to upper 50s sun.
Aviation /02z Monday through Friday/...
IFR/LIFR conditions were widespread early Sunday evening and little
change is seen through the 00z taf period...outside of temporary
improvement at sby. A cold front south of our taf sites from
southwest Virginia southeast into eastern North Carolina will slip slowly
to the south and stall near the NC/SC border. High pressure builds
from the north.
As of 23z...sby had improved to VFR under the influence of drier air
from the northeast. Kept MVFR in the forecast overnight wtih tempo
IFR through 04z. Kept IFR at the rest of the locations with
conditions varying between IFR and LIFR. Some drizzle or light rain
is expected. As low pressure moves along the aforementioned front...
rain and IFR ceilings take over at all the taf sites including sby.
Northeast winds will be the norm during the next 24 hours. These
winds may gust to around 20 knots overnight at orf.
Outlook...periods of rain and IFR conditions continue through
Wednesday with onshore NE winds at the surface and a moist west to
southwest flow aloft. As high pressure builds south into the Middle
Atlantic States...a cold air wedge will develop along the east side
of the Appalachians...contributing to the deterioration of aviation
A cold front sweeps from west to east across the Middle Atlantic States
Wednesday. A period of dry and VFR weather takes over Wednesday
night through Friday.
7 PM update...seas have built to 5 feet off of Virginia Beach (buoy
44099). Small Craft Advisory is in effect for all the coastal waters and the mouth
of the Chesapeake Bay.
Late this afternoon...a cold front has sagged just S of the County Warning Area into
NC...while hi pressure was bldng into southeast Canada. That hi will slide
into New England by Monday morng...then move off the CST Monday
aftn/eveng. Meanwhile...one low pressure area will lift into Tennessee/Kentucky
while a second weaker low develops off the middle Atlantic CST. This
scenario will result in rather strong north-northeast winds (15 to 25 kt) over
the waters...esply the coastal waters...southern ches Bay and Currituck sand.
Seas will build back to 4 to 7 feet...and waves in the ches Bay will
build to 2 to 4 feet. Winds will turn to the west or SW late Tuesday
afternoon/early Tuesday eveng...as the low off the CST moves away to the
east-northeast and a cold front starts to approach from the west. At this
time...have sca's for all the coastal waters through Tuesday afternoon...and for
the mouth of the ches Bay through Monday afternoon.
That cold front will cross the waters late Wednesday afternoon through Wednesday eveng.
SW winds will turn to the northwest...and with colder air expected to
move in behind the front...winds could be strong enough for Small Craft Advisory
conditions late Wednesday night through Thursday morng.
Marine...Small Craft Advisory until 5 PM EST Monday for anz634.
Small Craft Advisory until 5 PM EST Tuesday for anz650-652-654-