Severe Thunderstorm Warning 73, NWS Columbia, SC

FXUS62 KCAE DDHHMM
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
155 PM EDT WED JUN 16 1999

MODELS ARE NOT QUITE ON THE SAME PAGE WITH THE DETAILS OF THIS
FORECAST. THE GIVENS ARE THAT THE WARM MOIST UNSTABLE AIR MASS IN
PLACE OVER SC WILL REMAIN OVER THE STATE THROUGH TNGT. A COLD FRONT
WILL MOVE INTO THE STATE ON THU SLOWLY USHERING IN DRIER AIR BEHIND
IT. THE DETAILS IN QUESTION ARE THE TIMING AND LOCATION OF ANY MINOR
SHORTWAVES MOVING ACROSS THE AREA TNGT...THE TIMING AND MOVMENT OF
THE FRONT AS IT MOVES ACROSS THE STATE ON THU AND THU NGT...AND WHAT
HAPPENS TO THE FRONTAL ZONE ON FRI. WILL GO WITH AT LEAST LIKELY
POPS FOR TNGT TEMPS NEAR FWC.

THE RUC SEEMS TO PICK UP AND HANDLE THE MOVEMENT OF MINOR UPPER
LEVEL WAVES QUITE WELL IN THE SHORT TERM. IT INDICATES SOME NEUTRAL
TO WEAK PVA OVER CENTRAL SC THROUGH THE FIRST HALF OF TNGT. LO LVL
BOUNDARY LIES DIRECTLY OVER THE THE CWA WITH SFC STREAMLINE
CONVERGING ALONG THE BOUNDARY. AIR MASS IS MODERATELY UNSTABLE AND
CONVECTION IS CURRENTLY FIRING UPSTREAM OF OUR CWA OVER CENTRAL GA.
VIS INDICATES SOME BREAKS IN THE CLDS MOVING ALONG THE BOUNDARY.
THUS EXPECT CONVECTION TO AGAIN MOVE FROM SW TO NE ACROSS CENTRAL SC
THIS AFTN INTO THIS EVNG. BY 12Z THU...THE AVN HAS THE LO LVL
CYCLONIC CIRCULATION CENTER JUST N OF CHESTERFIELD WHILE THE ETA HAS
THE CENTER FURTHER WEST NEAR NEWBERRY. NOT A BIG DIFFERENCE. BY 18Z
BOTH MODELS MOVE THIS FEATURE OF INTO THE NC WITH THE FRONTAL
BOUNDARY TRAILING S BEHIND IT. BOTH THE AVN AND ETA HAVE THE FRONT
AS DEPICTED IN THE LI AND STREAMLINE FIELD OVER THE CWA IN A
MODERATELY UNSTABLE AIRMASS (SBLI AROUND -5). THUS THE MOISTURE,
INSTABILITY, AND FORCING ARE THERE AGAIN FOR ANOTHER ROUND OF
CONVECTION ABOUT MID-DAY ON THU. BEST CHC THOUGH LOOKS TO BE COASTAL
SECTIONS. WILL GO WITH LIKELY POPS AGAIN ON THU WITH TEMPS NEAR FWC.

AT THIS POINT MODELS BEGIN TO DIVERGE. THE ETA DEVELOPS ANOTHER
CYCLONIC CIRCULATION ALONG THE FRONT IN ERN GA THU NGT WHICH RETARDS
ITS EWRD PROGRESS. THIS LOOKS TO BE RELATED TO THE ETA/S HANDLING OF
THE VORT MAX CROSSING NRN FL INTO THE LOW COUNTRY LATE THU NGT. THE
AVN IS MUCH MORE PROGRESSIVE WITH THIS FEATURE AND AS A RESULT PLOWS
THE FRONT WELL OFFSHORE BY FRI MORNING. EVEN IF THE ETA SOLN IS
CORRECT, THIS FEATURE SHOULD PHASE WITH THE NRN STREAM ON FRI AND
MOVE QUICKLY E DURING THE DAY. MAIN EFFECT ON FCST WILL BE WITH
TEMPS AND WINDS THU NGT AND FRI. WILL GO WITH A 20 TO 30 POP ON THU
NIGHT BASED ON ETA/S HANDLING OF FRONT AND VORT TOGETHER WITH FWC
POP OF 40. MIGHT BE SOMTHING TO IT. AT THIS TIME...DO NOT PLAN TO
MENTION POP FOR FRI.

FOR THE EXTENDED PERIOD, THE 061600 MRF DROPS A VIGOROUS SHORTWAVE
SE OVER THE SRN GT LKS REGION AND CUTS THIS FEATURE OFF OVER SRN
IN/OH BY 00Z TUE. A SHORTWAVE MOVES N AROUND THE WRN PERIPHERY OF
THE BERMUDA HI TOWARD THE SE US OVER THE WEEKEND INTO MON. AT THE
SFC, HI PRES MOVES ACROSS THE NE STATES OVER THE ATLANTIC. A MOIST
RETURN FLOW OFF THE ATLANTIC SETS UP LATE SUN INTO MON. A LOOK AT
THE LAST THREE MODEL RUNS SHOWS THE RUNS IN GENERAL AGREEMENT AS TO
THE BROAD SCALE PATTERN...I.E., A MEAN TROF POSN OVER THE ERN US.
THEY DISAGREE AS TO THE DETAILS. FOR THE CAE CWA, WILL CONTINUE
TREND FOR AFTN TSTMS ON SUN AND MON INCREASING RH IN RETURN FLOW AND
APPROACHING VORT MAX. WILL USE SCT OR WIDELY SCT TERMINOLOGY. FMR
TEMPS LOOK OK, LOWS IN THE MIDDLE 60S AND HIGHS IN THE UPPER 80S.

.CAE...NONE.

CAMMARATA

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE COLUMBIA SC
406 PM EDT WED JUN 16 1999

TIME (EDT) .....CITY LOCATION....... ST   ...EVENT/REMARKS...
           .....COUNTY LOCATION.....

400 PM4     15 SW CAE                 SC   .75 INCH HAIL
06/16/99   LEXINGTON                      HIGHWAY PATROL AT I20 AND
                                          HIGHWAY 178

CDL