Hail in Missouri, April 27, 2002

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
330 PM CDT SAT APR 27 2002

AFTER WAITING AND WATCHING THINGS ARE FINALLY BGNG TO GET GOING OUT
WEST.  THE MID LVL DRY SLOT CONTS TO SURGE EWD ACRS THE FA ON THE
HEALS OF THE ERN MO IMPULSE HELPING ALG WITH WAA GENERATE THE SECOND
WV OF SHRA AND EMBDD -TSRA NOW MOVG EAST OF THE MS RVR.  SCT CNVCTN
IS NOW DVLPG ALG DRYLN FM SE NEB INTO ERN KS WHERE CLDS HV CLRD AND
DIURNAL HTG AND PBL MSTR ADVCTN HAS RESULTED IN A SWATH OF SFC BASED
INSTABILITY.  THE BIG QUESTION IS HOW FAR EWD THE INSTABILITY WL
SPRD DURING THE COURSE OF THE EVNG AND THE EXTENT OF THE CNVRGNC
ALG THE DRYLN.  WRMFNT WAS LCTD FM SRN IL ACRS THE LAKE OF THE
OZARKS INTO NW MO AT 20Z AND XTNSV LOW CLDS RMND OVR ALL OF THE
BI-STATE.  STILL ALL THE MDLS INCLUDING THE LAST SVRL RUC RUNS ARE
INDCG BOTH AN INCRS IN SFC DPTS AND TMPS THRU THE RMNDR OF THE AFT
AND INTO THE EVNG IN ADVANCE OF EWD SURGING DRYLN.  THIS INCRS IN
PBL MSTR/HEAT AND GOOD MID LVL CAA RESULTS IN THE MDLS MAINTAINING
THE SWATH OF UNSTBL AIR WELL PAST SUNSET INTO THE NGT IN ADVANCE OF
THE STG SYS.  DP LYR SHEAR IS IMPRSV TO SAY THE LEAST WITH LATEST
LAPS 0-6KM BULK SHEAR AT 70-80 KTS...AND VALUES CLOSE TO THESE SHUD
BE MAINTAINED DURING THE EVNG AS THE MID LVL JET CONTS TO PROP EWD
IN ASSOCN WITH THE STG SHRTWV TROF.  THUS SVR THREAT STILL LOOKS
GOOD IF PROGGED DESTABILIZATION IS INDEED CORRECT.  NATURE TO THE
FRCG SUGGESTS THAT COVERAGE OF STRMS SHUD BE SCT AND WL WORD AS
SUCH...ENDING WEST TO EAST DURING THE TNGT PD.

FAIRLY GOOD DRYING BHD THIS SYS AND MDLS ARE ALL NOW A BIT COOLER
THAN PRVS RUNS FOR SUN/SUN NGT.  HV TRENDED THE NEW FCST DOWNWARD A
TAD MORE BASICALLY SPLITTING THE DIF IN THE MAV/FWC NUMBS.  WL PRBLY
SEE SOME WRAP ARND CLDS WORK INTO THE FAR NORTH LATE TNGT AND AT
LEAST SCT INSTABILITY CU FRM SUN MRNG IN THE CYCLONIC FLOW IN THE
WAKE OF THE LOW OVR THE NRN/ERN SXNS.  BREEZY AS WELL.

SFC HI BLDS ACRS SUN NGT WITH ANY LINGERING INSTAB CU DSIPTG AND LVG
MCLR SKIES FOR A WHILE.  MDLS HOWEVER BGN SPRDG WAA CLDS ACRS THE
NRN HALF OF THE CWFA LATE SUN NGT IN ADVANCE OF A QUICK MVG
IMPULSE.  HV KEPT THE FCST DRY BUT WL HV TO WATCH TO SEE IF A FEW
SHRA MAY DVLP FM MID LVL MSTR DECK.

FM MON AND BYD THE FCST DETAILS BCM LESS CLR.  THE NEW AVN IS MUCH
DIF THAN THE PRVS RUN AND HAS TRENDED TWDS YDAS CANADIAN AND THE
LATEST UKMET/ECMWF SHWG MORE NRN STRM AMPLIFICATION AND THUS THE SWD
FNT PROGRESSION ON MON/MON NGT IS ABT 24H FASTER THAN PRVSLY FCST.
I HV KEPT SOME POPS GOING WITH IT AND HV TAILORED TMPS A BIT.  THE
EXACT PSN AND WAVERING IN RSPNS TO SHRTWVS STILL RMNS QUESTIONABLE
INTO WED.  ATTM AVN SUGGESTS THREAT OF ELEVATED TRW TUE NGT INTO
ERLY WED THEN SFC BASED STRMS LATE WED/WED NGT WITH SFC WV
TRANSLATING ALG THE E/W BNDRY.

.STL...NONE
GLASS