Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Raleigh NC
1235 am EST Wednesday Nov 25 2015
Synopsis...a ridge of high pressure will extend over the region
through the end of the week. A cold front will approach the area
from the north over the weekend.
Near term /tonight/...
as of 920 PM Tuesday...
Little change in the pattern with ridging at the surface and aloft
continuing over our area. Worth noting though..that the high center
is prognosticated to become re-established to our north...but the outcome
for our weather will be the same...dry weather with light winds.
With a gradual airmass moderation now underway.
Low amplitude shortwave energy over the Central Plains will track
east within the the near zonal flow aloft in place across much of
the southern and central Continental U.S....spreading scattered to broken
cirrus over the region tonight and through the first half of the
day on Wednesday.
Lows tonight should be several degrees warmer than this morning...
ranging in the lower to middle 30s.
Short term /Wednesday through Wednesday night/...
as of 215 PM Tuesday...
The surface high center will continue to shift east and north...moving
off the New England coast by mid-day. However...a ridge axis
connected to the aforementioned high will extend south across the
middle Atlantic and Carolinas in a cad fashion. Meanwhile...an
inverted surface trough will take shape just off the Carolina coast with
low level moisture pooling in that area. Low level streamline forecasts
show an eastward wind developing and thus suggests some of this
moisture will move inland late Wednesday and may result in some low
cloud and perhaps some fog by Wednesday night...especially across our eastern
zones. Otherwise until then...look for fair weather continuing
during the daytime Wednesday with ample sunshine filtered by high
clouds. Thickness trends and forecast soundings suggest only subtle
bl moderation through tomorrow...so look for highs similar to or
perhaps a few degrees warmer than today (mid 50s).
Long term /Thursday through Tuesday/...
as of 147 PM Tuesday...
High confidence in dry and mild conditions Thursday through
Saturday. A strong dry Air Ridge is forecast to extend down the
eastern Seaboard from offshore of New England Thursday into Friday
night or Saturday. Aloft... strong ridging is forecast to expand
from the Gulf Coast northwest across NC. The low level flow should be light
from the north-northeast with the middle and high level flow blocked by
the ridging. This will lead to dry but mild conditions into Saturday.
Lows generally in the 40s expected with highs in the 60s.
The confidence in the forecast is lower with details by Sunday into
next week with the rainfall forecast and temperatures. However...
the forecast track is expected to be well to our north and west and
this increases confidence in lighter quantitative precipitation forecast than west of the mountains.
Another high pressure will likely build down from the NE states
Sunday and Monday as the active storm track runs from The Rockies NE
through the plains then into the Great Lakes. This storm track
increases the threat of the high building south along the East Coast
again keeping temperatures cool.
Aviation /06z Wednesday through Sunday/...
as of 1235 am Wednesday...
VFR conditions very likely today and through much of this evening...
however we will see a trend toward sub-VFR conditions later tonight.
Deep high pressure stacked over the region and generally dry sinking
air through the column has kept skies clear with unrestricted visibilities
over central NC. The surface high centered over New England will
continue to drift east-northeast over the coastal Canadian Maritimes through
tonight while extending SW across the forecast area. Expect little
more than high thin clouds today as a weakening middle level wave now
over Missouri moves eastward into the region. The increasing low
level flow from the NE/east-northeast later today into tonight will draw
increasing Atlantic moisture into central NC... leading to
development of IFR stratus and fog toward the end of the taf valid
Looking beyond 06z Thursday... sub-VFR conditions should persist through
sunrise... followed by improvement back to VFR through Thanksgiving
day and evening. Another round of sub-VFR stratus/fog is expected
late Thursday night into Friday morning... then VFR conditions should return
from middle morning Friday through Sat... as another surface high closes
off over the forecast area... bringing an end to the Atlantic
onshore flow. A backdoor front is expected to push southward through
NC late Sat into Sat night... leading to a chance of sub-VFR
ceilings behind the front late Sat night through sun. -Gih