889
FXUS62 KRAH 301909
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
309 PM EDT Thu May 30 2024

.SYNOPSIS...
A vigorous mid and upper-level disturbance will pivot across and
offshore the southern Middle Atlantic through early Friday. Canadian
high pressure will otherwise extend across the region through early
Saturday, then drift off the coast of the Carolinas by Saturday
night.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 300 PM Thursday...

A shortwave trough comprised of a couple of perturbations now over
wrn PA and Lake Erie will dig sewd and across and offshore the
Middle Atlantic through tonight. A combination of associated 30-50
meter/12 hr height falls mb and 3-5 C cooling at 500 mb will
contribute to the development of generally shallow convection across
sern VA/nern NC this evening-early tonight. A few, associated
showers may result over the far ne Piedmont and nrn Coastal Plain
generally between 00-06Z. After otherwise diurnally-enhanced cumulus
dissipates, it will be mainly clear and unseasonably cool, with low
temperatures ranging from mid 40s in the rural nrn Piedmont to mid
50s in the Sandhills and srn Coastal Plain (~5-10 F below average).

&&

.SHORT TERM /FRIDAY AND FRIDAY NIGHT/...
As of 235 PM Thursday...

Canadian cool and dry.

A longwave ridge extending from the MS Valley to cntl Canada today
will progress east and extend from QC to the South Atlantic states
by 12Z Sat. Accompanying strong, 100-120 meter/12 hr mid-level
height rises --and the center of an underlying, ~1025-1026 mb
Canadian high --will spread from the lwr Great Lakes to the srn
Middle Atlantic, with associated tropospheric-deep subsidence over
cntl NC.

The influence of the Canadian ridge will yield cooler than average
temperatures in the 70s (~5-10 F below average) Fri and in the
middle 40s to lwr 50s (~10-15 F below average) Fri night, the latter
still about 5-8 F shy of record lows (GSO: 42, RDU: 42, FAY: 45).

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
As of 200 AM Thursday...

A series of northern stream lows will track eastward through Canada
through the middle of next week, with a number of s/w disturbances
rotating about the lows potentially impacting the weather across the
mid-Atlantic and Carolinas. The sub-tropical ridge will progress
slowly eastward through the area Sat/Sat night as a s/w trough move
eastward through the MS Valley. This s/w will then continue
generally eastward across the Appalachians and through the mid-
Atlantic Sun/Mon, however the timing and track differ between the
medium-range guidance. Another s/w will follow behind it but,
similar to the first s/w, the model differences continue wrt timing
and track. A northern stream s/w ejecting eastward from a low over
western Canada will deepen as it moves along the US/Canada border
Tue/Wed, closing off over then tracking eastward through the Great
Lakes Wed/Wed night. At the surface, cool high pressure move slowly
esewd through the Carolinas Sat/Sat night. The high will move ese to
off the Carolina/Southeast US coast on Sun, where it should sit
through Mon then slowly drift eastward Tue/Wed. A warm front should
lift through the area Sun night/Mon, with southerly return flow once
again advecting warm, moist air into the area through early next
week. Surface flow should become increasingly swly as the high
shifts further offshore, with more of a Gulf influence by mid-week.
A bit of a low confidence precipitation forecast from Sun through
Wed given the uncertainty wrt the shortwaves. For now, expect
largely dry weather through Sun, with chances for precipitation
returning for Sun night through Wed. Temperatures should be near to
slightly below normal through Sun, then return to near/above normal
and moderate through mid next week.

&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
As of 155 PM Thursday...

Canadian high pressure will build from the Great Lakes swd and
across the Carolinas, with associated influence for light nly
surface winds and VFR conditions through Friday. There will,
however, be a slight chance of a shower near and northeast of RWI
early tonight, accompanying the passage of a vigorous mid/upr-level
disturbance.

Outlook: Return flow warmth and moisture, combined with a lee trough
or weak surface front, will result in a chance of mainly diurnal
showers/storms Sunday through the middle of next week.

&&

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

&&

$$
SYNOPSIS...MWS
NEAR TERM...MWS
SHORT TERM...MWS
LONG TERM...KC
AVIATION...MWS