Special Weather Statement, NWS Columbia, SC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
530 PM EDT SUN JUL 22 2012

.SYNOPSIS...
UPPER LEVEL RIDGE OVER THE CENTRAL PART OF THE COUNTRY WILL REMAIN
ENTRENCHED AND BUILD SLIGHTLY EAST THROUGH THE WEEK. THIS WILL
BRING MORE SUMMER LIKE CONDITIONS WITH HIGH TEMPERATURES IN THE
MIDDLE 90S THROUGH MUCH OF THE WORK WEEK. THE ONLY RELIEF WILL
COME IN THE FORM OF ONLY A SLIGHT CHANCE OF LATE AFTERNOON OR
EARLY EVENING SHOWERS OR THUNDERSTORMS.

&&

.NEAR TERM /TONIGHT/...
ISOLATED TO SCATTERED SHOWERS/THUNDERSTORMS WILL CONTINUE ACROSS
PORTIONS OF THE MIDLANDS AND CSRA THROUGH THE LATE AFTERNOON AND
EARLY EVENING HOURS. THE MAIN THREAT FROM ANY STORMS WOULD BE
SOME STRONG GUSTY DOWNBURST WINDS WITH A BIT OF AN INVERTED V
SOUNDING NEAR THE SURFACE AND LOCALLY HEAVY RAIN WITH PW VALUES
JUST UNDER 2 INCHES. OVERNIGHT...LOWS WILL ONCE AGAIN FALL ONLY
INTO THE MIDDLE 70S.

&&

.SHORT TERM /MONDAY THROUGH WEDNESDAY NIGHT/...
NORTHWESTERLY FLOW ALOFT WILL DOMINATE THROUGH THIS PERIOD OF THE
FORECAST AS THE CENTER OF THE UPPER RIDGE REMAINS OVER THE CENTRAL
PLAINS AND UPPER LEVEL TROUGHING DEVELOPS OVER THE GREAT LAKES
INTO THE NORTHEASTERN STATES. THIS PATTERN WILL ALLOW FOR SEVERAL
SHORTWAVES TO DIVE SOUTHEASTWARD THROUGH THE OHIO VALLEY INTO THE
MID ATLANTIC...TRIGGERING AND SUSTAINING DIURNAL CONVECTION
THROUGH MID WEEK.

THE 850MB NORTHWEST FLOW WILL ADD A DOWNSLOPING COMPONENT TO THE
WIND AND HELP RAISE AFTERNOON TEMPERATURES INTO THE MID AND UPPER
90S THROUGH THE PERIOD. PRECIPITABLE WATER VALUES CONTINUE TO
HOVER AROUND THE 2 INCH MARK...PROVIDING AMPLE MOISTURE AND
WHEN COMBINED WITH THE HOT TEMPERATURES WILL SUPPORT A MODERATE TO
STRONGLY UNSTABLE ATMOSPHERE. HAVE DECIDED TO INCREASE LATE
AFTERNOON AND EARLY EVENING POPS FOR MONDAY TO CHANCE ACROSS THE
NORTHERN MIDLANDS WHERE BOTH THE NAM/GFS SHOW A LINE OF CONVECTION
DEVELOPING OVER THE PIEDMONT OF NC AND SLIDING SOUTHEASTWARD.

DIURNAL CONVECTION IS EXPECTED BOTH TUE/WED WITH THE POSSIBILITY
OF SHORTWAVE ENERGY TRIGGERING AND SUSTAINING THE
CONVECTION...DESPITE 700MB TEMPERATURES AROUND +10C WHICH WOULD
TYPICALLY CAP STORM DEVELOPMENT. OVERNIGHT LOWS WILL BE IMPACTED
BY POTENTIAL CONVECTIVE DEBRIS CLOUDS AND A NIGHTLY NOCTURNAL LOW
LEVEL JET WHICH WILL HELP KEEP THE BOUNDARY LAYER MIXED. HEAT
INDICES WILL ALSO SURPASS 100 DEGREES EACH DAY AND IN SOME
LOCATIONS EXCEED 105 DEGREES.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
MEDIUM RANGE MODELS CONTINUE TO BE IN FAIR AGREEMENT REGARDING THE
OVERALL UPPER PATTERN.  ON THURSDAY...UPPER RIDGING DOMINATES OVER
THE SOUTHEASTERN PART OF THE COUNTRY AND CONTINUES INTO EARLY
FRIDAY. UPSTREAM AMPLIFICATION OF 500 MB FLOW RESULTS IN A SHORTWAVE
TROUGH PUSHING ACROSS THE GREAT LAKES REGION AND OHIO VALLEY LATE
FRIDAY INTO EARLY SATURDAY AS THE UPPER RIDGE BECOMES SUPPRESSED.
THE UPPER TROUGH AXIS SWINGS ACROSS THE FORECAST AREA SATURDAY AND
SATURDAY NIGHT...THEN PUSHES EAST OF THE FORECAST AREA BY SUNDAY AS
UPPER RIDGING BUILDS IN FROM THE WEST.  A FRONTAL BOUNDARY
APPROACHES THE AREA WITH THE UPPER TROUGH ON SATURDAY BUT LIKELY
WILL NOT REACH THE FORECAST AREA AND INSTEAD WILL STALL OUT TO THE
NORTH.

TEMPERATURES DURING THIS PERIOD SHOULD BE ABOVE NORMAL WITH HIGHS IN
THE MID TO UPPER 90S THURSDAY AND FRIDAY AND COOLING SLIGHTLY TO THE
MID 90S OVER THE WEEKEND. THE HOT TEMPERATURES COMBINING WITH
PRECIPITABLE WATER VALUES CLOSE TO 2 INCHES DURING THIS PERIOD WILL
YIELD DIURNAL CHANCES OF CONVECTION THROUGH THE PERIOD WITH POSSIBLY
HIGHER CHANCES FRI/SAT AS SHORTWAVE ENERGY APPROACHES THE REGION.

&&

.AVIATION /22Z SUNDAY THROUGH FRIDAY/...
VFR CONDITIONS EXPECTED THROUGH THE TAF PERIOD.

CUMULUS AROUND 5K FT WILL CONTINUE THROUGH THE AFTERNOON
HOURS. THE CUMULUS WILL BE MOSTLY SCATTERED BUT BROKEN AT TIMES.
ALTHOUGH THUNDERSTORMS SHOULD REMAIN SCATTERED...THEY ARE FORMING
CLOSE ENOUGH TO MOST TAF SITES TO INCLUDE MENTION OF
SHOWERS/STORMS FOR THE NEXT FEW HOURS. STRONG GUSTY WINDS AND
BRIEF MVFR CONDITIONS MAY BE ENCOUNTERED IN THE STRONGER STORMS IF
THEY IMPACT A TAF SITE.

EXTENDED AVIATION OUTLOOK...RESTRICTIONS POSSIBLE EACH DAY IN
EARLY MORNING FOG AND AFTERNOON CONVECTION AS A MOIST AIR MASS
REMAINS OVER THE REGION.

&&

.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&