Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC-- Highlight Changed Discussion --
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FXUS62 KRAH 250646
Area Forecast Discussion
National Weather Service Raleigh NC
146 AM EST Sat Feb 25 2017
A strong low pressure system will push through the Great Lakes
tonight. This will allow an associated cold front to cross our
region on Saturday. Cooler high pressure will build into the area
Saturday night and Sunday.
.NEAR TERM /TONIGHT/...
As of 1025 PM FRIDAY...
Mainly clear with a light SSEly breeze, and temperature mainly in
the 50s overnight.
A narrow ridge of surface high pressure remains over Ern NC this
evening, between a pre-frontal line of convection and closely
following cold front over central KY/TN,and a pair of surface lows a
few hundred miles off the coast of the Carolinas. The MSL pressure
gradient over mainly the Wrn half of NC will tighten late tonight,
as the aforementioned cold front nears the W slopes of the
Appalachians by 12Z. A light SSEly surface wind will consequently
gradually increase overnight, particularly W of I-95 (away from the
lingering narrow surface ridge axis). Associated modest radiational
cooling, with projected 12Z low level thickness values around 1375
meters, favor lows about a category below consensus guidance.
.SHORT TERM /SATURDAY AND SATURDAY NIGHT/...
As of 342 PM FRIDAY...
Deepening cyclone will lift north into Ontario and Quebec, with
attendant trailing sfc cold front crossing the area Saturday
afternoon/evening. With the better dynamics and deeper moisture
lifting off to the north, accompanying band of convection will
weaken across North Carolinas, with only isolated to scattered
convection skirting across the northern tier.
Temperatures will approach record territory once again, especially
across the south-southeastern tier where it will remain mostly dry.
Highs ranging from mid 70s NW to lower 80s SE. It will be breezy as
well, with sustained winds of 15 to 18 kts, gusting to 25 to 30kts.
As far as severe potential: Steep low-level rates from the
unseasonably strong diurnal heating along with mid-level lapse rates
of 6.8 to 7.50 C/Km will result in weak destabilization of 500 to
1000 J/Kg across central NC. Given impressive 50 to 60kts of
unidirectional shear, it will be possible to see an isolated strong
to severe wind gust across the northern tier.
Strong post-frontal dry cold air advection Friday evening/night
will result in abrupt clearing and seasonable overnight lows
in the lower 30s NW to upper 30s/near 40 SE.
.LONG TERM /SUNDAY THROUGH FRIDAY/...
As of 205 PM Friday...
A broad upper level trough covering most of the contiguous U.S. will
result in a slightly unsettled weather pattern across the U.S. this
period. Temperatures, overall, are expected to remain above or well
above normal through mid-week. Afterwards, lower than normal heights
translates to near or slightly below normal temperatures for the
later half of the work week.
A series of upper disturbances will keep the atmosphere slightly
unsettled across central NC for the beginning of this period. High
pressure building into our region Sunday in the wake of an exiting
s/w and attendant sfc cold front will lead to drier cool conditions
Sunday. This high quickly scoots offshore Monday, leading to an
appreciable warm up with high temps expected to be about 8-10
degrees warmer than Sunday afternoon highs.
Models in general agreement lifting a mid-upper level across the
Deep South and the Southeast U.S. Monday night into Tuesday,
leading to a chance of showers. At this time, the highest threat for
rain across central NC appears to be late Monday night into early
Tuesday. A more amplified s/w will begin to affect our region
Wednesday with another chance for showers and possibly a few
thunderstorms late Wednesday into Wednesday night. This system exits
our region Thursday morning, leading to a more stable and cooler
Ahead of the mid week system, temperatures will once again average
10-20 degrees above normal with Wednesday`s high temps most likely
in the 75-80 degrees range. Cooler temperatures anticipated Thu-Fri
as a l/w trough develops over the eastern U.S.
.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
-- Changed Discussion --As of 130 AM Saturday...
24 Hour TAF Period: Patchy sub-VFR conditions (MVFR-LIFR) are
expected to develop across central NC early this morning, mainly
across the eastern TAF sites (KRDU/KFAY/KRWI). Any sub-VFR
conditions that develop should quickly lift within an hour of two of
sunrise this morning, with increasing south to southwesterly winds
in advance of an approaching cold front. Expect winds to increase
into the 15 to 20 mph range by mid to late morning, with gusts of up
25-30 mph possible late morning into the afternoon. A cold front an
associated broken band of showers and storms will move across the
area this afternoon. The best convective coverage will be across
northern portions of the area, where we could see a few strong to
damaging wind gusts accompanying the strongest storms. Sub-VFR
conditions will be possible with any convection. Winds will veer to
westerly just behind a cold front that will cross the area
immediately behind the showers/storms, during the afternoon hours,
then to northwesterly. Wind will decrease to around 7 to 13 mph
range by this evening, with some gusts of around 20-23 mph still
possible through mid evening.
Outlook: High pressure will build in from the west tonight through
Sun, moving east and offshore Mon. The next chance for sub-VFR
conditions will be Mon night, lasting through Tue night and perhaps
into Wed, as southwest flow brings in low level moisture and an
increased risk for showers, as well low stratus and fog, especially
dusk through dawn.
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Record highs for February 25:
Greensboro: 81 (1930)
Raleigh: 82 (1930)
Fayetteville: 85 (1930)