Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 250237
AFDLSX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ST LOUIS MO
937 PM CDT FRI JUL 24 2015

.UPDATE:
ISSUED AT 934 PM CDT FRI JUL 24 2015

WEATHER LOOKS PRETTY TRANQUIL FOR THE REMAINDER OF THE EVENING AND
INTO THE FIRST PART OF THE OVERNIGHT PERIOD. THE CLUSTER OF STORMS
WHICH REGENERATED OVER CENTRAL MO EARLY THIS EVENING HAS REMAINED
WELL TO THE WEST, TRACKING SOUTH/SOUTHWEST ALONG THE INSTABILITY
GRADIENT AND LARGELY STEERED BY NORTHERLY CLOUD LAYER FLOW. THE THREAT
OF ADDITIONAL STORMS OVERNIGHT SHOULD BE PRIMARLY AFTER 200-300
AM. THE COMBINATION OF SUBTLE WEAK MID LEVEL DISTURBANCES TRACKING
ALONG THE PERIPHERY OF THE HIGH ALOFT ALONG WITH WEAK LOW-LEVEL
WAA AND MOISTURE CONVERGENCE, SUPPORT A THREAT OF POTENTIALLY
MAINTAINING A FEW OF THE STORMS ACROSS SOUTHEAST IA/NW MO, BUT
MORE LIKELY NEW STORM DEVELOPMENT ACROSS NORTHEAST MO INTO CENTRAL
MO.

GLASS

&&

.SHORT TERM:  (THROUGH LATE TONIGHT)
ISSUED AT 356 PM CDT FRI JUL 24 2015

MCS WILL CONTINUE TO WORK SOUTHWARD ALONG THE CAPE GRADIENT DURING
THE NEXT FEW HOURS.  THIS IS ALSO IN THE SAME DIRECTION AS THE
FORWARD PROPAGATING CORFIDI VECTORS.  THERE REMAINS THE POTENTIAL
FOR SOME SEVERE WIND GUSTS WITH THIS SYSTEM AS THE RAP FORECAST
SOUNDINGS AHEAD OF IT AT KCOU ARE SHOWING INVERTED-V PROFILES.  THE
LATEST OBJECTIVE ANALYSIS WHICH SHOWS MLCAPES BETWEEN 3000-4000 J/KG
AND 0-6KM SHEAR NEAR 40KTS.  HAVE INCREASE POPS EARLY THIS EVENING
OVER THE EASTERN OZARKS AS THIS SYSTEM MOVES SOUTHWARD ACROSS
EASTERN MISSOURI.  HAVE ALSO KEPT CHANCES OVER NORTHEAST AND CENTRAL
MISSOURI INTO WEST CENTRAL ILLINOIS LATE THIS EVENING INTO THE
OVERNIGHT HOURS AS BOTH THE NAM AND GFS ARE SHOWING A SHORTWAVE
TROUGH MOVING EAST SOUTHEAST INTO THE AREA WHICH SHOULD PROVIDE SOME
ASCENT, AND THE RAP IS SHOWING AND INCREASE IN LOW LEVEL MOISTURE
CONVERGENCE OVER THE NORTHERN HALF OF THE CWA.  GOING TEMPERATURES
LOOK GOOD FOR LOWS.

BRITT

.LONG TERM:  (SATURDAY THROUGH NEXT FRIDAY)
ISSUED AT 356 PM CDT FRI JUL 24 2015

THUNDERSTORM TRENDS REMAIN THE KEY QUESTION FOR THE WEEKEND.  HAVE
BASICALLY ONLY TWEAKED THE MIDNIGHT SHIFT`S POPS FOR THE WEEKEND.
THIS BREAKS DOWN TO 30-50% CHANCES FOR THE ENTIRE AREA SATURDAY
THROUGH SUNDAY.  HIGHER DEWPOINT TEMPERATURES OVER WESTERN AND
CENTRAL MISSOURI SHOULD OVERSPREAD MUCH OF THE AREA PUSHING CAPE
VALUES OVER 3000 J/KG.  LINGERING BOUNDARY IN THE VICINITY OF THE
MISSISSIPPI RIVER SHOULD PROVIDE ENOUGH FOCUS FOR AFTERNOON
CONVECTION TO FIRE THOUGH COVERAGE IS UNCERTAIN DUE TO A DECENT CAP.
NOT OVERLY IMPRESSED WITH THE DEEP LAYER SHEAR, BUT WITH THE HIGH
INSTABILITY THERE IS CERTAINLY ENOUGH TO BE CONCERNED WITH MULTI-
CELL CLUSTERS CAPABLE OF PRODUCING STRONG WINDS.

TEMPERATURES ON SATURDAY ARE UNCERTAIN DUE TO THE CHANCES FOR
CONVECTION.  HOWEVER, IT DOES APPEAR THAT WE`LL GET WARM ENOUGH TO
REACH HEAT ADVISORY CRITERIA OVER PARTS OF CENTRAL AND SOUTHEAST
MISSOURI WHERE THUNDERSTORM COVERAGE LOOKS TO BE MORE WIDELY
SCATTERED TO ISOLATED.  WILL GO AHEAD AND ISSUE AN ADVISORY FOR
THESE AREAS FOR SATURDAY FOR HEAT INDEX VALUES AROUND 105.  ADVISORY
MAY NEED TO BE EXPANDED IF STORMS DO NOT DEVELOP AS EXPECTED...OR
POSSIBLY DROPPED IF THE THUNDERSTORM COVERAGE IS GREATER THAN
EXPECTED.

ANOTHER SHORTWAVE IS FORECAST TO MOVE OVERHEAD SATURDAY NIGHT
ASSOCIATED WITH A MODEST LOW LEVEL JET WILL CONTINUE THE THREAT FOR
STORMS OVER MUCH OF THE AREA SUNDAY LOOKS TO BE A REPEAT OF OF
SATURDAY WITH THE SYNOPTIC BOUNDARY CONTINUING TO BE REINFORCED BY
THUNDERSTORMS.  THUNDERSTORM CHANCES SHOULD BE WANING QUICKLY THOUGH
FOR SUNDAY NIGHT INTO THE BEGINNING OF NEXT WEEK AS A STRONG UPPER
LEVEL RIDGE BUILDS ACROSS THE AREA.  THINK THE VAST MAJORITY OF THE
AREA SHOULD BE DRY BY LATE SUNDAY NIGHT AND MONDAY WITH ONLY SLIGHT
CHANCE POPS MONDAY AND TUESDAY.  MEDIUM RANGE MODELS HAVE A WEAK COLD
FRONT MOVING THROUGH THE AREA WEDNESDAY NIGHT INTO THURSDAY WITH
ANOTHER CHANCE FOR STORMS.

CARNEY

&&

.AVIATION:  (FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 610 PM CDT FRI JUL 24 2015

MAIN QUESTION OVERNIGHT WILL BE DEVELOPMENT OF FG. CURRENT TRENDS
SHOW BEST CHANCES OF DEVELOPMENT WILL BE AT COU/SUS/CPS WHERE
WINDS WILL BE LIGHTER. ATTM, THREAT LOOKS MINIMAL BUT TRENDS WILL
BE MONITORED. OTHERWISE, THREAT FOCUS TURNS TO CHANCES FOR TSRA
LATE TONIGHT INTO SAT MORNING. MDLS CONTINUE TO SHOW A THREAT FOR
UIN AROUND SUNRISE, WHICH MAY THEN DEVELOP SWD IMPACTING SUS/CPS
AND PERHAPS COU LATE IN THE MORNING AND INTO THE AFTN HRS.
HOWEVER, CONFIDENCE IN THIS SOLN IS TOO LOW TO ADD TO TAFS ATTM.

SPECIFICS FOR KSTL: HAVE KEPT TAF VFR AND DRY THRU THE PERIOD FOR
NOW. TSRA MAY DEVELOP INTO THE REGION LATE SAT MORNING INTO THE
AFTN HRS. HOWEVER, CONFIDENCE IN THIS SOLN IS TOO LOW ATTM.

TILLY

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...HEAT ADVISORY FROM NOON TO 7 PM CDT SATURDAY FOR BOONE MO-
     CALLAWAY MO-COLE MO-CRAWFORD MO-FRANKLIN MO-GASCONADE MO-
     IRON MO-MONITEAU MO-MONTGOMERY MO-OSAGE MO-REYNOLDS MO-
     WARREN MO-WASHINGTON MO.

IL...NONE.
&&

$$

WFO LSX


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