Area Forecast Discussion Issued by NWS Raleigh/Durham, NC
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000
FXUS62 KRAH 182047
AFDRAH
Area Forecast Discussion
National Weather Service Raleigh NC
447 PM EDT Mon Mar 18 2024
.SYNOPSIS...
A vigorous upper-level disturbance and reinforcing surface cold
front will move across NC early tonight. Canadian high pressure will
follow and build across the Southeast through Tuesday.
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.NEAR TERM /THROUGH TONIGHT/...
As of 345 PM Monday...
A deepening positively tilted upper level trough over the OH valley
this afternoon will continue to tilt overnight tonight as it become
more neutral by early Tuesday morning and positioned off the Mid-
Atlantic coast. A the surface, the cold front is now well off shore
this afternoon but mid and high clouds are still streaming across
much of the region this afternoon. As the upper and surface trough
moves over the OH valley, more clouds will move in over night, but
clear out by Tuesday morning. Winds this afternoon are generally
W/NW minus a few areas in the Sandhills and S. Coastal Plain still
reporting a SW wind. By late evening and continuing into the
overnight hours, the entire region is expected to be NW winds 10-15
mph and gusts of 20-25 mph mainly due to the mid/upper trough moving
across the region overnight and supplemental mixing to the surface.
Temperatures tonight will be the coldest of the forecast with lows
ranging in the upper 20s along the VA border and low to mid 30s
elsewhere. The growing season has begun in southern portions of
Central NC, and with high confidence that temperatures will be
between 29 and 31 degrees in some SW central NC counties, A Freeze
Warning is valid tonight at midnight through Tuesday 9am. Everyone
in the Freeze Warning area should take extra time to protect their
tender plants/crops from the sub-freezing temperatures tonight.
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.SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/...
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As of 400 PM Monday...
Strong flow aloft will develop Tuesday with a strong ridge along the
West Coast and a deep low across SE Canada. At the surface, high
pressure will build further east into the Deep South, switching
surface flow from westerly to southwesterly across central NC. Winds
will strengthen during the day due to the approaching surface high
and a deep low moving SE, just north of the Great Lakes. Wind gusts
of 20 to 25 mph are possible across much of the area. A dry airmass
across the region will help dew point temperatures drop into the
teens Tuesday afternoon, and with highs approaching the mid to upper
50s, relative humidity will lower to 20 to 30 percent across most
areas. With dry fuels in place across much of the area, an Increased
Fire Danger Statement has been issued for the northern Piedmont,
Coastal Plain and eastern Sandhills for late in the morning through
early evening.
Winds will somewhat diminish in the evening, and with clear skies,
good radiational cooling will make for a chilly night with lows near
normal to 5 degrees below normal. Increasing thicknesses will keep
most areas from dropping below freezing.-- End Changed Discussion --
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.LONG TERM /WEDNESDAY THROUGH MONDAY/...
As of 320 PM Monday...
By Wednesday morning, low pressure will be centered over
southeastern Ontario with a cold front extending to the southwest,
with the influence of high pressure contained close to the Gulf
Coast. The cold front will move across the area from northwest to
southeast during the afternoon/evening hours, bringing an increase
in wind during that period. The dry conditions that have been
present through the week will continue both Wednesday and Thursday,
although the wind speeds will be less behind the front on Thursday.
The combination of higher wind and low relative humidity could bring
an increased fire danger on Wednesday. The frontal passage itself
will not bring any precipitation itself as there won`t even be much
moisture for cloud cover.
Behind the cold front, high pressure will extend southeast from
central Canada into the Carolinas on Thursday. The high will shift
east Thursday night, and by Friday morning, rain will be approaching
the area from the southwest related to a developing low over the
Gulf of Mexico. The GFS/GEFS has consistently remained a quicker
solution compared to the ECMWF/EPS, especially in regards to the low
center, but there is enough agreement between models to increase
pops to likely for all locations except the northwestern quadrant of
the forecast area Friday afternoon/night. The 12Z GFS shows the low
over the Delmarva Peninsula Saturday morning, while the 12Z ECMWF
still has the low center off the coast of Georgia. Will have pops
decreasing through Saturday and Sunday, keeping some pops in case
the slower European solution does verify. All models agree that
precipitation will have moved offshore by Sunday night and Monday as
high pressure builds over eastern Canada and a ridge extends south
along the East Coast.
There is high confidence that Wednesday will be the warmest of the
next seven days in advance of the cold front, with highs ranging
from the mid 60s to the mid 70s. Temperatures should be at or below
normal through the rest of the forecast. The day with the most
uncertainty to the high temperatures is Friday, as there could be a
short-lived cold-air damming episode with high pressure briefly over
New York as the Gulf of Mexico low advances northeast. Overnight
lows will be above freezing throughout the extended period, and no
need for frost/freeze headlines is anticipated.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
As of 200 PM Monday...
VFR conditions expected to continue through the next 24 hours. Mid
and high clouds are streaming across the region as an upper level
trough moves across the region today and tonight. Gusty winds of 15
to 20 kts are expected to continue this afternoon and into the
overnight hours. Surface winds of 5 to 10 mph this afternoon will
shift from a northerly wind to west-northwest wind by the late
evening. A few areas of virga could occur at the 3 eastern sites
overnight but no flight restrictions are expected. Otherwise skies
will clear early Tuesday morning through the afternoon.
Outlook: LLWS will be possible Tues night into early Wed as winds at
2k ft increase to 30-40 kts. A dry cold frontal passage will bring a
wind shift out of the NW late Wed into early Thurs. A storm system
approaches the area Fri afternoon into Sat bringing a high chance
for sub-VFR conditions.
&&
.FIRE WEATHER...
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As of 400 PM Monday...
Elevated fire weather conditions are possible at times through mid-
week as relative humidity drops to 20 to 30 percent, and wind gusts
increase to 20-25 mph. Relative humidity will drop to the
aforementioned values in the afternoons through Thursday, however
wind gusts of 20 to 25 mph are mostly expected Tue and Wed
afternoons. With dry fuels across most areas, an Increased Fire
Danger Statement has been issued for the northern Piedmont, Coastal
Plain and eastern Sandhills for late Tue morning through the early
evening.
Refer to your local burn-permitting authority on whether you may
burn. If you do burn, exercise extreme caution.-- End Changed Discussion --
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
Freeze Warning from midnight tonight to 9 AM EDT Tuesday for
NCZ073>076-083-084.
&&
$$
SYNOPSIS...MWS
NEAR TERM...CA
SHORT TERM...JJT
LONG TERM...Green
AVIATION...CA/Swiggett
FIRE WEATHER...JJT