Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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FXUS62 KRAH 181843
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
243 PM EDT Wed Apr 18 2018

.SYNOPSIS...
A dry cold front will move east through the area late tonight through
late Thursday morning. Cool high pressure will build into the
Carolinas Thursday night through Saturday.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 243 PM Wednesday...

Tonight: Sfc cold front will cross the mountains aoa midnight and
will push east into the NC Piedmont during the predawn hours.
Moisture is very limited with the front. So aside from a brief
period of some broken high base stratocumulus immediately
along/ahead of the front, dry conditions will prevail. A steady 10
to 15 kt breeze will support mild temperatures overnight. Lows
generally in the lower to mid 60s. The exception will be across the
far NW zones where the late onset of CAA behind the cold front could
allow temperatures to fall into the mid/upper 50s right around
daybreak.

&&

.SHORT TERM /THURSDAY AND THURSDAY NIGHT/...
As of 245 PM Wednesday...

Sfc cold front will exit the coastal plain counties by mid-late
morning. Soundings remain very unimpressive wrt sufficient
moistening and essentially no instability given strong inversion
aloft. Thus, thus will keep forecast dry. Otherwise, drier cooler
air will advect into the area by the afternoon and will continue
overnight, with blustery W-NWLY winds gusting between 25 to 30 kts
by mid to late morning and continuing into the afternoon. Initially,
the cold air advection may be offset by low-level westerly downslope
flow, but by the afternoon a more nly direction could allow
temperatures to fall slightly. Highs ranging from 60 NW to lower/mid
70s SE.

Continued CAA Thursday night will result in the first of two chilly
nights to come. Lows overnight in the 35 to 40 range. A steady 5 to
7 kt range should preclude widespread frost development. However
it`s possible that patchy frost could develop in sheltered areas,
especially across the NW Piedmont where the pressure gradient
relaxes towards daybreak.


&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
As of 230 PM Wednesday...

An upper level ridge and surface high pressure over the Midwest will
keep conditions cool and dry for the end of the week and into the
weekend. Temperatures for Friday and Saturday will generally be in
the 60s with lows in the 40s. On Friday night a few of the VA border
counties might drop into the mid to upper 30s, so it is possible
that a frost advisory may be needed but will continue to monitor
temperatures as latest guidance was slightly warmer than prior
forecasts. Clouds will begin to increase Sunday as high pressure
sets up offshore in a hybrid or in-situ damming scenario. This wont
happen until late in the day however, which will allow temperatures
to rise into the upper 60s to near 70 degrees Sunday afternoon.

For early next week, strong hybrid cold air damming sets up on
Monday and isentropic lift increases over the area. In addition, a
low pressure system will try to move into the area from the
southwest, however, strong high pressure may keep it further south
than the GFS solution suggests. The EC solution does keep it well to
the south. A blend of the two ramps up precipitation chances on
Monday, especially across the western Piedmont. Whether the
precipitation is from the isentropic lift or the approaching low
remains to be seen but regardless, expect rain chances to increase
early next week and an unsettled pattern will prevail through
Wednesday. Highs will be in the 60s with lows in the upper 40s
across the Piedmont to low 50s in the southeast.

&&

.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
As of 130 PM Wednesday...

In advance of a dry cold front that will cross the region late
tonight through Thursday morning, gusty SWLY winds of 20 to 25 kts
are expected to develop late this afternoon and evening. While sfc
winds will remain between 10 to 15 kts overnight, a strong 50 to 55
kt low level jet crossing east through the area will support a
period of LLWS this evening and into the overnight hours. In the
wake of the cold front moving east of the area during the mid to
late morning hours, gusty conditions are expected again on Thursday,
with WNW winds gusting 25 to 30 kts, strongest at KFAY and KRWI.

Dry VFR conditions are expected to persist into the weekend. The
next threat for sub VFR ceilings may occur as early as Sunday night,
but may hold off until late Monday or Monday night.

&&

.FIRE WEATHER...
Coordination with neighboring NWS offices and the North Carolina
Forestry Service has led to the issuance of Increase Fire Danger
statement today across sections of western and central NC, and
across the bulk of the state for Thursday.

Across central NC, the most critical fire weather parameters today
will be across sections of the southern Piedmont into the Sandhills
as lower dewpoints and warm afternoon temperatures will yield late
afternoon humidity values in the 25-30 percent range. This will
occur at about the same time the strongest wind gusts will occur
(19Z-22Z) with gusts 22-25kts.

On Thursday, minimum humidity values in the afternoon will bottom
out between 25 to 35 percent areawide with gusty westerly-nw sfc
winds of 25 to 30 kts developing in the wake of the exiting cold
front from mid morning into the afternoon hours. Based on what fire
activity occurs today, and if model dewpoint guidance comes in
lower, cannot rule out the possibility of a short-fused Red Flag
Warning for parts of central NC on Thursday.

&&

.RAH WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$
SYNOPSIS...CBL
NEAR TERM...CBL
SHORT TERM...CBL
LONG TERM...ELLIS
AVIATION...CBL
FIRE WEATHER...WSS



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