Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC-- Highlight Changed Discussion --
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FXUS62 KRAH 200133
Area Forecast Discussion
National Weather Service Raleigh NC
933 PM EDT Sun Mar 19 2017
Pacific high pressure will build southeastward across NC tonight,
then off the southeast U.S. coast Monday afternoon. A lead wave of
low pressure and preceding warm front will cross the southern Middle
Atlantic states Monday night. The trailing cold front and a
secondary wave of low pressure will move through the Carolinas Tue
.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --AS OF 930 PM Sunday...
High pressure building overhead, between the upper low filling
off the NC coast and a building ridge over the central US,
combined with clear skies and PW down to .20" will result in
optimal radiation cooling overnight. Most areas are already
calm, and lows will likely drop below most guidance in rural
cool spots, with upper 20s to mid 30s and areas of frost Monday
Our Spring Frost/Freeze Warning/Advisory program is scheduled
to begin on March 27. As a result, the potential for frost or a
light freeze will be conveyed via the HWO. -Vincent
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.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
As of 145 PM Sunday...
Monday: High pressure building over the region tonight will move
offshore during the day Monday as a cold front approaches the
central/ southern Appalachians from the west. As a result, warm
advection will commence from west-east Monday afternoon as initially
calm or light/variable winds become WSW ~10 knots. Expect mostly
sunny skies with highs ~10F warmer than today, ranging from ~60F in
the NE Coastal Plain to mid 60s in the W/SW Piedmont.
Monday Night: Low-level moisture will increase from the west
overnight as the cold front progresses slowly east into the
Appalachians and low-level flow strengthens in response to a
tightening MSLP/height gradient downstream over the Carolinas. Model
guidance is fairly unanimous in generating a few hundredths of an
inch of precip via elevated showers late Monday night (06-12Z Tue)
over N/NW portions of central NC. With a dry airmass initially in
place over the region and forcing (aside from warm advection)
confined to transient small amplitude waves in NW flow aloft,
confidence is low with regard to whether or not sufficient
moistening /elevated destabilization/ and forcing will exist for
elevated showers to develop. At this time, will indicate a slight
chance of showers after midnight across the northern and western
Piedmont. With increasing cloud cover and a SW breeze Monday night,
expect lows to be much warmer than tonight, in the mid to upper 40s,
coolest in the E/NE Coastal Plain. -Vincent
.LONG TERM /TUESDAY THROUGH SUNDAY/...
As of 225 PM Sunday...
Tuesday is still looking warm and cloudy as a backdoor cold front
organizes across the Ohio Valley. Scattered Showers are expected to
develop, mainly in the afternoon and in the west where a lee trof
will be set up by westerly flow. Broad troffing with a lack of
supporting trigger and dynamics provide a weak regime for stronger
convection and will keep only isolated mention for thunder. Cold air
holds off until later Tuesday night, with highs on Tuesday climbing
into the low and mid 70s in the downslope regime despite extensive
cloudiness. The front will be sagging slowly south and into the
region Tuesday night, with at least a likely chance for showers.
Mins will fall off more quickly after midnight, and readings should
be in the mid 40s north to upper 40s south Wednesday morning. The
front will be slipping south of the area early with rain lingering
in the southern tier counties perhaps into the early afternoon. High
pressure will be building in Wednesday with cool air advection and
slow clearing limiting highs to the mid 50s across the north, while
the southern tier may reach low 60s. Cooler airmass and clear skies
will promote good radiational cooling late Wednesday night, with
widespread lower 30s and possibly some sub-30 readings along the
northern border Thursday morning. Cool and dry weather is on tap for
Thursday, with highs topping out from 50 to 55 under sunny skies.
Surface high pressure over the area on Thursday will shift east and
offshore on Thursday night, while an upper ridge axis migrates east
and over the area on Friday. These will result in a warming trend
into the weekend, with highs Friday returning to seasonable readings
in the 60s, and further into the lower 70s Saturday.
A cold front will approach the area late Saturday, with showers and
thunderstorms becoming increasingly widespread Saturday night and
into the day Sunday as the front moves through.
.AVIATION /02Z MONDAY THROUGH FRIDAY/...
As of 825 PM Sunday...
There is a high confidence of VFR conditions through the TAF period,
as high pressure builds SEwd across our forecast area through Mon.
Surface winds will consequently be light and variable, with a
northerly component amidst periods of calm tonight, and a southerly
one by Mon afternoon. Skies will be mainly clear.
Outlook: The passage of a wave of low pressure and parent frontal
zone will result in a good chance of sub-VFR conditions and rain
Tue night-early Wed.