Area Forecast Discussion
Issued by NWS Columbia, SC

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FXUS62 KCAE 201050
AFDCAE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
650 AM EDT SUN JUL 20 2014

.SYNOPSIS...
AN UPPER-LEVEL TROUGH AND AN ASSOCIATED FRONTAL SYSTEM WILL REMAIN
IN CONTROL OF THE FORECAST AREA/S WEATHER THROUGH EARLY THIS WEEK.
THE WEATHER WILL REMAIN UNSETTLED.

&&

.NEAR TERM /THROUGH TONIGHT/...
TODAY...
A WARM FRONT EXTENDED THROUGH THE SOUTH PART OF THE FORECAST
AREA EARLY THIS MORNING. MOISTURE HAS BECOME SOMEWHAT SHALLOW BEHIND
A MID-LEVEL SHORTWAVE TROUGH. RADAR SHOWED SCATTERED SHOWER
COVERAGE. THE SHOWERS WERE MAINLY ASSOCIATED WITH WEAK ISENTROPIC
LIFT AND CONVERGENCE NEAR THE FRONT.

THE NAM WAS MORE PROGRESSIVE LIFTING THE WARM FRONT NORTHWARD TODAY
COMPARED TO THE GFS. THERE IS LOW CONFIDENCE IN THE TEMPERATURE
FORECAST TODAY BECAUSE OF THE MODEL INCONSISTENCY BUT WE LEANED
TOWARD THE COOLER GUIDANCE BECAUSE OF CLOUDINESS AND SHOWERS.

THE NAM AND GFS DISPLAY THE H5 FLOW BACKING LATER TODAY AHEAD OF
ANOTHER SHORTWAVE TROUGH WITH INCREASED MOISTURE MAINLY IN THE
SOUTHEAST SECTION OF THE FORECAST AREA. THIS SUPPORT PLUS DIURNAL
HEATING SHOULD BRING INCREASED SHOWER COVERAGE THIS AFTERNOON. THE
SPC WRF INDICATED SCATTERED COVERAGE TODAY BECOMING MORE
CONCENTRATED IN THE CSRA LATE THIS AFTERNOON.

DIURNAL HEATING PLUS COOLING ALOFT ASSOCIATED WITH THE UPPER TROUGH
SHOULD HELP SUPPORT THUNDERSTORMS AS WELL. THE AMOUNT OF INSTABILITY
IS QUESTIONABLE BECAUSE OF CLOUDINESS AND UNCERTAINTY WITH THE
PLACEMENT OF THE WARM FRONT. THE NAM DISPLAYS SURFACE-BASED LI/S
LOWERING TO AROUND -4. WATER VAPOR IMAGERY TRENDS INDICATE THERE MAY
BE LINGERING MID-LEVEL DRYNESS WHICH WOULD AID DOWNDRAFTS. THERE
SHOULD ALSO BE ADDED SHEAR ASSOCIATED WITH THE WARM FRONT.
THUNDERSTORMS WITH DAMAGING WIND MAY OCCUR BUT THE THREAT APPEARS
LOW AT THIS TIME BECAUSE OF LIKELY WEAK INSTABILITY MAINLY BECAUSE
OF CLOUDINESS. PRECIPITABLE WATER VALUES NEAR 2 INCHES PLUS A SLOW
STORM MOVEMENT INDICATE LOCALLY HEAVY RAIN MAY OCCUR WITH SOME OF
THE THUNDERSTORMS.

TONIGHT...
THE NAM AND GFS SHOW DEEP MOISTURE AHEAD OF THE UPPER
TROUGH IN THE FORECAST AREA TONIGHT. THE MODELS DISPLAY A SURFACE
TROUGH GENERALLY SHIFTING INTO THE COASTAL PLAIN OR JUST OFF THE
COAST. THERE MAY BE ENHANCED LIFT ASSOCIATED WITH THE RIGHT ENTRANCE
REGION OF THE H25 JET. WE LEANED TOWARD THE HIGHER GUIDANCE POPS
BECAUSE OF THIS PATTERN. PRECIPITABLE WATER NEAR 2 INCHES AND A SLOW
STORM MOVEMENT INDICATE LOCALLY HEAVY RAIN MAY OCCUR WITH SOME OF
THE SHOWERS OR THUNDERSTORMS. USED THE GUIDANCE CONSENSUS FOR THE
TEMPERATURE FORECAST.

&&

.SHORT TERM /MONDAY THROUGH MONDAY NIGHT/...
THE NAM AND GFS DISPLAY AN INVERTED TROUGH NEAR THE COAST THROUGH
MONDAY NIGHT WITH HIGH MOISTURE INLAND. THE NAM IS MORE
PRONOUNCED WITH THE H5 TROUGH BECOMING A CUT-OFF LOW WITH A
DIFLUENT PATTERN OVER THE FORECAST AREA. THERE MAY ALSO BE LIFT
ASSOCIATED WITH THE RIGHT ENTRANCE REGION OF AN H25 JET. THE
MODELS INDICATE PRECIPITABLE WATER AROUND 2 INCHES. HEAVY RAIN MAY
OCCUR ALTHOUGH THE HEAVIER AMOUNTS MAY OCCUR CLOSER TO THE TROUGH
NEAR THE COAST. THE PATTERN SUPPORTS THE HIGHER GUIDANCE POPS. THE
HIGH TEMPERATURE GUIDANCE WAS CLOSE BUT MAY BE TOO WARM BECAUSE OF
CLOUDINESS. USED THE GUIDANCE CONSENSUS FOR THE LOW TEMPERATURE
FORECAST.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
THE GFS AND ECMWF SHOW UPPER TROUGHING CONTINUING OVER THE
FORECAST AREA DURING THE MEDIUM-RANGE PERIOD. THE MODELS DISPLAY A
SURFACE TROUGH NEAR THE AREA DURING MUCH OF THE PERIOD WITH A COLD
FRONT NEAR THE REGION FRIDAY AND SATURDAY. THE GFS AND ECMWF MOS
SUPPORT CHANCE POPS THROUGH THE PERIOD WITH TEMPERATURES NEAR
CLIMATOLOGY.

&&

.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
VARIABLE CONDITIONS EXPECTED THROUGH THE TAF PERIOD.

SURFACE OBS INDICATE AREAS OF MVFR/IFR CONDITIONS WITH WSR-88D
RADARS SHOWING SCATTERED SHOWERS ACROSS THE AREA. EXPECT MVFR/IFR
CONDITIONS CURRENTLY AT TAF SITES TO IMPROVE TO VFR BY 14Z. UPPER
LEVEL DISTURBANCE MOVING INTO THE AREA FROM THE WEST WILL RESULT
IN INCREASING CHANCES OF SHOWERS AND THUNDERSTORMS THIS AFTERNOON
INTO TONIGHT. HAVE INCLUDED VCSH FOR ALL TAF SITES AS CONFIDENCE
IN TIMING AND COVERAGE REMAINS TOO LOW TO INCLUDE IN TAFS ATTM.
EXPECT CONVECTIVE ACTIVITY TO PERSIST INTO TONIGHT AS THE
DISTURBANCE STALLS OVER THE AREA. WINDS THROUGH THE TAF PERIOD
WILL BE SOUTHEASTERLY AT VARIABLE AT 5 KNOTS OR LESS.

EXTENDED AVIATION OUTLOOK....CIG/VSBY RESTRICTIONS POSSIBLE MONDAY
THROUGH THURSDAY DUE TO PLENTY OF LOW-LEVEL MOISTURE ACROSS THE
AREA.  ANOTHER COLD FRONT WILL APPROACH THE REGION ON
THURSDAY...WHICH COULD BRING ADDITIONAL STORMS TO THE REGION.

&&

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

$$







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