878
FXUS63 KLSX 291725
AFDLSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE SAINT LOUIS MO
1225 PM CDT THU JUL 29 2021
SHORT TERM
(THROUGH LATE TONIGHT)
ISSUED AT 332 AM CDT THU JUL 29 2021
THE STRONG UPPER LEVEL RIDGE REMAINS IN PLACE ACROSS THE WESTERN TWO
THIRDS OF THE CONUS WITH A SHORTWAVE MOVING THROUGH THE NW FLOW OVER
THE GREAT LAKES. AT THE SURFACE, THE CENTER OF A BROAD HIGH IS
SITUATED NEAR THE MISSOURI BOOTHEEL. TO OUR NORTH, THERE IS A LOW
CENTERED NEAR THE WI/MN/IA BORDERS ASSOCIATED WITH THE SHORTWAVE,
A COLD FRONT EXTENDING TO THE WSW OF THE LOW, AND A RATHER ROBUST
QLCS MOVING SOUTH THROUGH NORTHERN ILLINOIS.
THE QLCS HAS FINALLY BEGUN TO WEAKEN, BUT IT IS MOVING IN A MUCH
FURTHER SOUTH THAN ANY GUIDANCE ANTICIPATED. WHILE THE ODDS OF
ANY OF THIS PRECIPITATION REACHING OUR CWA ARE LOW, WE'RE LIKELY
GOING TO SEE QUITE A BIT OF CLOUD COVERAGE THIS MORNING, ESPECIALLY
OVER OUR ILLINOIS COUNTIES. THESE CLOUDS WILL LIKELY LIMIT TEMPERATURES
A BIT, BUT WSW SURFACE AND LOW LEVEL WINDS WILL CONTINUE TO ADVECT
VERY WARM AND MOIST AIR INTO THE REGION. GIVEN A WARM START TO THE
DAY AND DEWPOINTS IN THE 70S, HEAT ADVISORY CRITERIA (HX OVER 105)
STILL SEEMS LIKE A SAFE BET DESPITE MORE CLOUDS THAN EXPECTED,
ESPECIALLY ALONG AND WEST OF THE MISSISSIPPI. THEREFORE WILL BE
KEEPING THE HEAT ADVISORY IN PLACE AS-IS.
THE ABOVE COLD FRONT IS EXPECTED TO PUSH INTO THE REGION SOMETIME
THIS EVENING AS THE UPPER RIDGE BEGINS TO BREAK DOWN. MOST OF THE
CAMS DEVELOP AT LEAST ISOLATED/SCATTERED STORMS ALONG THE FRONT,
WHICH SEEMS REASONABLE GIVEN THE FRONTAL FORCING AND MID/UPPER
LEVEL HEIGHT FALLS. WHILE STORM COVERAGE MAY BE LIMITED A BIT BY
VERY WARM TEMPS JUST ABOVE THE SURFACE, STORMS SEEM PRETTY LIKELY
AT THIS POINT. THESE STORMS WILL DEVELOP IN A VERY UNSTABLE AND
MODERATELY SHEARED ATMOSPHERE, WHICH MAY ALLOW A FEW STORMS TO
BECOME STRONG TO SEVERE. HOWEVER, WITH ONLY 20-25KT 0-3KM BULK
SHEAR, STORM ORGANIZATION AND SEVERE POTENTIAL WILL BE LIMITED,
WITH DAMAGING WINDS AND LARGE HAIL BEING THE INITIAL THREATS. AS
THE FRONT BEGINS TO STALL OVERNIGHT, WE MAY SEE SOME STORM
TRAINING. MOST STORMS SHOULD BE VERY EFFICIENT RAINFALL PRODUCERS
GIVEN PRECIPITABLE WATER NEAR 2" AND WARM CLOUD DEPTHS NEAR 4KM.
IF ANY AREAS ARE HIT BY MULTIPLE ROUNDS OF STORMS, SOME FLOODING
MAY BE POSSIBLE.
BSH
LONG TERM
(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 332 AM CDT THU JUL 29 2021
THE UPPER RIDGE WILL FINALLY BREAK DOWN AS WE MOVE INTO THE WEEKEND
THANKS TO AN AMPLIFYING TROUGH OVER THE EASTERN CONUS. A SERIES
OF SHORTWAVES WILL BRING REINFORCING SHOTS OF SEASONABLY COOL AIR
INTO THE REGION, KEEPING THE FRONT LAID OUT SOMEWHERE IN THE
VICINITY OF THE MIDDLE MISSISSIPPI/LOWER MISSOURI RIVER VALLIES.
WHILE UNCERTAINTY REMAINS REGARDING FRONTAL POSITIONING, THE
STALLED/SLOW MOVING FRONT MAY RESULT IN MULTIPLE ROUNDS OF SHOWERS
AND STORMS FOR SOME AREAS. WHILE THE LATEST GUIDANCE IS
HIGHLIGHTING SATURDAY WITH THE HIGHEST ODDS FOR PRECIPITATION,
THERE IS AT LEAST A CHANCE OF PRECIPITATION SOMEWHERE IN THE CWA
FROM FRIDAY THROUGH SATURDAY. ANY STORMS THAT DO DEVELOP WILL ALSO
LIKELY BE RATHER EFFICIENT RAINFALL PRODUCERS GIVEN AMPLE PRECIPITABLE
WATER ALONG AND SOUTH OF THE FRONT. THIS AGAIN MAY RESULT IN AT
LEAST ISOLATED FLASH FLOODING IN AREAS THAT DO SEE MULTIPLE ROUNDS
OF STORMS.
THE UPPER TROUGH TO OUR EAST WILL CONTINUE TO DEEPEN INTO NEXT WEEK,
EVENTUALLY PUSHING THE FRONT OUT OF THE REGION. THIS WILL PUT AN
END TO OUR RAINFALL CHANCES AND RESULT IN A CONTINUED PERIOD OF
COOLER CONDITIONS THROUGH MIDWEEK.
BSH
AVIATION
(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1224 PM CDT THU JUL 29 2021
THE MAIN FOCUS FOR IMPACTS THIS PERIOD WILL BE A SOUTHWARD MOVING
COLD FRONT AND ASSOCIATED STORM POTENTIAL. THIS FRONT IS CURRENTLY
ACROSS SOUTHERN IOWA AND NORTHERN MISSOURI, AND IS EXPECTED TO MOVE
OVER THE KUIN TERMINAL LATER THIS AFTERNOON. AT THAT TIME, STORMS
WILL FORM ALONG THE FRONT, BUT COVERAGE IS EXPECTED TO BE ISOLATED
TO SCATTERED, SO CONFIDENCE IS NOT HIGH ENOUGH TO HAVE DIRECT IMPACT
TO THE TERMINAL MENTIONED IN THE TAF AT THE MOMENT. AS THE FRONT AND
ASSOCIATED STORMS MOVE FURTHER SOUTH THIS EVENING, STORM COVERAGE IS
EXPECTED TO LESSEN, DECREASING CONFIDENCE FURTHER IN DIRECT IMPACTS
TO THE REMAINING LOCAL TERMINALS, INCLUDING KSTL. FOR ALL LOCAL
TERMINALS, STORMS THAT DO DIRECTLY IMPACT TERMINALS WILL BE CAPABLE
OF HEAVY RAINFALL AND GUSTY WINDS, SO SUB-VFR FLIGHT CONDITIONS ARE
POSSIBLE. THE FRONT IS ANTICIPATED TO CLEAR ALL LOCAL TERMINALS BY
TOMORROW MORNING EXCEPT KCOU AND KJEF WHERE THE FRONT MAY LINGER, SO
I'VE LEFT VCSH IN THE TAF FOR NOW. WITH THE FRONT'S PASSAGE, WINDS
WILL SHIFT TO OUT OF THE NORTH AND REMAIN LIGHT.
ELMORE
PRELIMINARY POINT TEMPS/POPS
SAINT LOUIS 98 74 86 67 / 5 40 30 40
QUINCY 93 71 82 64 / 40 50 20 70
COLUMBIA 96 74 87 70 / 0 20 30 40
JEFFERSON CITY 97 76 89 71 / 0 20 30 30
SALEM 97 70 84 63 / 20 40 10 20
FARMINGTON 97 72 88 67 / 0 20 40 10
LSX WATCHES/WARNINGS/ADVISORIES
MO...HEAT ADVISORY UNTIL 9 PM CDT THIS EVENING FOR AUDRAIN MO-BOONE
MO-CALLAWAY MO-COLE MO-CRAWFORD MO-FRANKLIN MO-GASCONADE MO-
IRON MO-JEFFERSON MO-KNOX MO-LEWIS MO-LINCOLN MO-MADISON MO-
MARION MO-MONITEAU MO-MONROE MO-MONTGOMERY MO-OSAGE MO-PIKE
MO-RALLS MO-REYNOLDS MO-SAINT CHARLES MO-SAINT FRANCOIS MO-
SAINT LOUIS CITY MO-SAINT LOUIS MO-SAINTE GENEVIEVE MO-
SHELBY MO-WARREN MO-WASHINGTON MO.
IL...HEAT ADVISORY UNTIL 9 PM CDT THIS EVENING FOR ADAMS IL-BOND IL-
BROWN IL-CALHOUN IL-CLINTON IL-FAYETTE IL-GREENE IL-JERSEY
IL-MACOUPIN IL-MADISON IL-MARION IL-MONROE IL-MONTGOMERY IL-
PIKE IL-RANDOLPH IL-SAINT CLAIR-WASHINGTON IL.
WFO LSX
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