Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
FXUS62 KRAH 290600
Area Forecast Discussion
National Weather Service Raleigh NC
200 AM EDT FRI JUL 29 2016
An upper level disturbance will track just to the north of the
region tonight around the hot high pressure over the
Southeastern US. A surface trough of low pressure will stall across
the area through the weekend.
.NEAR TERM /THROUGH TONIGHT/...
As of 845 pm Thursday...
The excessive heat warning and heat advisory have been allowed to
expire as heat index values have dropped below critical limits.
The Subtropical ridge in place over the SE U.S. has kept the
afternoon/evening showers and storms to the west and north of
central NC. Expect this will generally continue, though an isolated
shower and/or storm is still possible across far northern and
western reaches of the area (via outflow boundaries possibly making
it into the area from ongoing convection to the north and west of
central nc) for the next several hours. Otherwise, expect dry
conditions overnight, with low temps generally in the lower to mid
70s, with a few locations across the far SE/E remaining in the upper
.SHORT TERM /FRIDAY AND FRIDAY NIGHT/...
As of 320 PM Thursday...
Low-level thicknesses and heights aloft fall slightly on Friday as
the subtropical high shifts just east of the area and broad troughiness
begins to settle into the area from the west. However of more significance,
is the potential for dewpoints to mix out into the upper 60s and lower 70s
Friday afternoon owing to the low-level westerly flow that
develops in the wake of the surface low exiting off the Mid-Atlantic
Coast. So despite similar afternoon temperatures in the lower 90s NW to upper
90s SE, the drier air will suppress heat indices with current forecast
grids showing only the far SE zones close to advisory criteria.
Confidence is too low at this time to warrant the issuance of an
advisory with this package so will let midnight shift re-evaluate.
Expect the westerly low-level flow east of the mountains to also suppress
convection Friday afternoon, maintaining isolated/slight chance of diurnally
Lows Friday night in the lower to mid 70s.
.LONG TERM /SUNDAY THROUGH THURSDAY/...
-- Changed Discussion --As of 200 AM Friday...
Broad troughing aloft over the central MS river valley will progress
eastward over the Carolinas and Mid-Atlantic through early next
week, followed by a period of NW flow aloft mid-week as an upper
level ridge re-strengthens over the lower MS river valley and Deep
South, followed by a ridging aloft late next week as the
aforementioned ridge builds E/NE over the Carolinas and Mid-Atlantic.
With the above in mind, expect a cooling trend late the weekend
through early next week with temperatures becoming near normal,
followed by an increase in temperatures by late week as ridging
aloft returns to the region. With broad troughing aloft, expect
above-normal chances for convection sunday and early next week, with
chances somewhat more ambiguous in NW flow aloft by mid-week,
followed by below normal chances for convection late-week. With
central NC situated on the southern periphery of the westerlies and
eventually a period of NW flow aloft, an above normal potential for
severe weather will exist if small amplitude waves and/or upstream
convection /MCVs/ progress into/across the region, particularly in
vicinity of peak heating. -Vincent
-- End Changed Discussion --
.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
As of 815 PM Thursday...
VFR conditions are expected with some patchy early morning ground
fog possible late tonight. Scattered to isolated storms are possible
again tomorrow afternoon, but chances of a storm occurring at a TAF
site are too low to include.
Outlook: Outside of isolated to scattered storms each
afternoon/evening and some patchy early morning fog, expect
predominately VFR conditions through Friday. Rain chances are
expected to increase by the weekend and into early next week.