FXUS62 KRAH 031038
AREA FORECAST DISCUSSION
National Weather Service Raleigh NC
638 AM EDT Wed Jun 3 2020
Subtropical high pressure near Bermuda will direct hot and humid
southwesterly flow across the Southeast for the rest of the week.
.NEAR TERM /THROUGH TONIGHT/...
As of 350 AM Wednesday...
The main branch of the mid-latitude westerlies will remain across
the nrn US and Great Lakes this period. Within a weaker, srn branch,
a couple of shortwave troughs centered this morning over sern
OK/nern TX and the nrn Gulf of Mexico will drift generally ewd and
extend from the srn Appalachians to the nrn Gulf of Mexico by 12Z
Thu, while a mid level ridge drifts across and offshore the
At the surface, a summer-like pattern of sub-tropical high pressure
centered near Bermuda and an Appalachian lee trough, the latter of
which will strengthen and drift ewd with diurnal heating across the
NC Foothills and wrn Piedmont, will favor hot and increasingly humid
conditions today, with high temperatures in the upr 80s to lwr 90s.
Scattered showers and storms will focus with terrain circulations
over the Blue Ridge, and perhaps on a more isolated basis within the
lee trough, including over the far wrn NC Piedmont late this
afternoon and evening. Muggy overnight, with temperatures mostly in
the 70s, to briefly upr 60s prior to daybreak.
.SHORT TERM /THURSDAY AND THURSDAY NIGHT/...
As of 400 AM Wednesday...
A trough aloft initially stretching from the srn Appalachians to the
nrn Gulf of Mexico will direct a series of associated vorticity
maxima newd across the Carolinas Thu afternoon and night. Associated
moisture and weak ascent characterized by 10-20 meter mid level
height falls will favor the development of primarily diurnal
convection over cntl NC Thu afternoon and evening, relatively
maximized along a couple of surface features: 1) a lee trough over
the nw NC Piedmont and 2) along the inland-migrating sea breeze.
While generally weak deep tropospheric flow will limit storm
organization to pulse/multi-cellular modes, moderate to pockets of
strong instability, with diurnal heating into the upr 80s to around
90 degrees, will favor strong to isolated damaging wind gusts from
precipitation-loaded/wet microbursts. Gradually increasing low level
moisture/humidity will also favor areas of stratus development Thu
night-Fri morning, with lows again in the upr 60s to lwr 70s.
.LONG TERM /FRIDAY THROUGH TUESDAY/...
As of 235 AM Wednesday...
Friday and Saturday: The weak upper trough sitting over the eastern
US will slowly migrate eastward Friday and offshore on Saturday as a
high builds out west. At the surface, a trough will slowly amplify
through Saturday, with increasing southerly flow into the area.
Expect the usual diurnal weather pattern of generally dry weather
overnight with showers/storms during the aft/eve with higher chances
for convection on Saturday than Friday. Expect highs in the upper
80s to low 90s and lows in the upper 60s to low 70s.
Saturday night through Tuesday: A shortwave swinging through the
upper trough will surge southward into the mid-Atlantic Saturday
night/Sunday. Meanwhile at the surface, a backdoor cold front will
push south into the area. The best chances for convection will be
along and south of the front Saturday and Sunday as it slides south
into and through the area. The extent and strength of the convection
will depend on the diurnal timing and available instability. The
front could stall over, or slowly drift south through central NC
Sunday into Monday, complicating the forecast of both temperatures
and precipitation as they will be highly dependent on the location
of the front. However, both should decrease overall for early next
week, especially across the north and northeast portions of the area
as the surface high slides southeast from the eastern Great Lakes to
off the mid-Atlantic coast.
Tropical Storm Cristobal will remain over the Bay of Campeche and
Mexico through late week, but is expected to strengthen as it
migrates north over the Gulf this weekend. It will likely move
inland over TX/LA Sunday or Monday while the sub-tropical ridge
extends north along the east coast and into the mid-Atlantic. No
impacts are expected for the Carolinas through Tuesday as the lower
Mississippi Valley will see the greatest impacts from Cristobal.
.AVIATION /11Z WEDNESDAY THROUGH SUNDAY/...
As of 635 AM Wednesday...
VFR. Light swly surface winds this morning will increase to between
10-15 kts with gusts up to 15-20 kts this afternoon, in the MSL
pressure gradient between high pressure near Bermuda and an
Appalachian-lee trough that will sharpen with diurnal heating. An
isolated storm will be possible along that lee trough in the
vicinity of INT/GSO around 00Z, but the probability of occurrence is
too low to include in the TAF at this time.
Outlook: Hot and humid swly flow will result in a chance of mainly
afternoon and evening showers and storms and late night-early
morning stratus through the weekend.
Back to Main Forecast Discussion Page