123
FXUS63 KLSX 082359
AFDLSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE SAINT LOUIS MO
559 PM CST THU DEC 8 2022
SHORT TERM
(THROUGH LATE FRIDAY NIGHT)
ISSUED AT 211 PM CST THU DEC 8 2022
CURRENT WATER VAPOR IMAGERY SHOWS SOUTHWESTERLY FLOW ACROSS THE
MIDDLE MISSISSIPPI VALLEY WITH A SHORTWAVE OVER THE CENTRAL PLAINS.
THE UPPER-LEVEL JET STREAK AND LOW-LEVEL JET MAINLY RESPONSIBLE FOR
THE EARLY DAY RAIN ACROSS SOUTHERN PORTIONS OF THE CWA HAVE MOVED
EASTWARD, SHIFTING THE AREA OF RAIN AWAY FROM THE AREA. IN ITS WAKE,
WEAK WARM AIR ADVECTION AHEAD OF THE SHORTWAVE AND CORRESPONDING
SURFACE LOW IS PRODUCING WIDELY SCATTERED AREAS OF LIGHT RAINFALL
ACROSS THE CWA. THIS IS EXPECTED TO CONTINUE THROUGH THE AFTERNOON
INTO THIS EVENING.
THE AFOREMENTIONED SURFACE LOW THAT CAN BE FAINTLY MADE OUT IN
SURFACE OBSERVATIONS OVER KANSAS WILL MOVE NORTHEASTWARD THIS
EVENING INTO NORTHERN MISSOURI AND IOWA. LIFT FROM THIS FEATURE AND
THE ASSOCIATED SHORTWAVE WILL INCREASE RAIN COVERAGE MAINLY OVER
NORTHEASTERN MISSOURI AND WEST-CENTRAL ILLINOIS TONIGHT AHEAD OF A
COLD FRONT. THIS COLD FRONT WILL SWEEP THROUGH THE AREA LATE TONIGHT
INTO TOMORROW MORNING, BRINGING AN END TO THE RAIN AT THE
LATEST SHORTLY AFTER SUNRISE TOMORROW MORNING.
THE POST-FRONTAL AIRMASS IS NOT PARTICULARLY POTENT IN TERMS OF
TEMPERATURES, BUT WILL USHER DRIER AIR INTO THE REGION. THIS WILL
RESULT IN TEMPERATURES PEAKING TOMORROW AFTERNOON AT TO JUST ABOVE
CLIMATOLOGICAL VALUES UNDER CLEARING SKIES FOR MUCH OF THE CWA. THE
EXCEPTION TO THIS WILL BE NORTHEASTERN MISSOURI AND WEST-CENTRAL
ILLINOIS WHERE DENSER CLOUD COVER IS EXPECTED TO LINGER.
ELMORE
LONG TERM
(SATURDAY THROUGH NEXT THURSDAY)
ISSUED AT 211 PM CST THU DEC 8 2022
OUR FOCUS FOR THIS PORTION OF THE FORECAST PERIOD REMAINS ON
MULTIPLE ROUNDS OF RAINFALL AND THE POTENTIAL FOR EARLY WEEK
THUNDERSTORMS.
ON SATURDAY, ENSEMBLE CONSENSUS IS THAT A SHORTWAVE WILL QUICKLY
PROGRESS THROUGH THE CENTRAL PLAINS AND MIDWEST. IN RESPONSE, A WEAK
SURFACE LOW WILL FORM ALONG A STALLED BOUNDARY TO OUR SOUTH AND
TRACK EASTWARD TOWARD THE CWA. AHEAD OF THIS LOW, AN UPPER-LEVEL JET
STREAK WILL PAIR WITH ISENTROPIC LIFT VIA A LOW-LEVEL JET
INTERACTING WITH THE BOUNDARY TO BRING ANOTHER ROUND OF RAINFALL TO
PORTIONS OF THE AREA. THE PROBABILITY FOR RAINFALL IS HIGHEST OVER
SOUTHEASTERN MISSOURI AND SOUTHWESTERN ILLINOIS WHERE NEARLY EVERY
ENSEMBLE MEMBER HAS RAINFALL OCCURRING SATURDAY MORNING INTO THE
DAY. HOWEVER, CONFIDENCE IN RAINFALL DECREASES FURTHER NORTHWARD
ALONG THE I-70 CORRIDOR, WITH A VERY SHARP GRADIENT EXPECTED IN
RAINFALL VS. LITTLE TO NO RAINFALL. RAIN CHANCES WILL DECREASE
THROUGH THE AFTERNOON AND EVENING AS THE BETTER FORCING ALOFT AND
SURFACE LOW MOVE EASTWARD.
THERE IS HIGH CONFIDENCE THAT SUNDAY THROUGH MUCH OF MONDAY WILL BE
RELATIVELY CALM AND DRY AS ENSEMBLE CONSENSUS IS THAT AN UPPER-LEVEL
RIDGE WILL BUILD INTO THE PLAINS AND MIDWEST. AT THE SURFACE, HIGH
PRESSURE WILL KEEP CONDITIONS CALM AND SURFACE FLOW TO SOME DEGREE
EASTERLY. THIS SURFACE FLOW WILL KEEP TEMPERATURES AROUND
CLIMATOLOGICAL NORMALS THROUGH THIS TWO-DAY STRETCH, WITH ENSEMBLE
GUIDANCE CONVERGING ON HIGHS IN THE UPPER 40S FOR MUCH OF THE AREA.
THROUGH MONDAY INTO TUESDAY, A TROUGH WILL DEEPEN ACROSS THE
INTERMOUNTAIN WEST, WITH A LEADING SHORTWAVE WITHIN THE TROUGH
EJECTING OUT INTO THE CENTRAL PLAINS ON TUESDAY. IN RESPONSE, A
SURFACE LOW WILL DEVELOP AND DEEPEN ACROSS THE CENTRAL PLAINS,
SWINGING A COLD FRONT INTO THE MIDWEST. AS THIS OCCURS, THE GENERAL
CONSENSUS IS THAT THE LOW WILL OCCLUDE AS THE UPPER-LEVEL TROUGH
BECOMES CUT OFF FROM THE MAIN FLOW, HOWEVER, THERE IS STILL
DISAGREEMENT ON THE TIMING AND PROGRESSION OF THE OCCLUSION. THIS
UNCERTAINTY HAS IMPLICATIONS IN HOW UNSTABLE THE AIRMASS IS ABLE TO
GET AHEAD OF THE COLD FRONT ON TUESDAY. THE NUMBER OF GLOBAL
ENSEMBLES THAT HAVE AT LEAST 100 J/KG OF SBCAPE CONTINUES TO
INCREASE, BUILDING CONFIDENCE IN AT LEAST THUNDERSTORMS OCCURRING
AMONG THE WIDESPREAD RAINFALL ASSOCIATED WITH THE FROPA. HOWEVER,
THE THREAT OF STRONG TO SEVERE STORMS REMAINS MORE UNCERTAIN, AS
ENSEMBLES STILL DISAGREE WITH HOW UNSTABLE WE BECOME OR IF THE
OCCLUDING LOW CUTS OFF THE WARM SECTOR SOUTH OF THE CWA. THEREFORE,
THE THREAT OF STRONG TO SEVERE STORMS REMAINS LOW AT THIS LEAD TIME,
BUT CONTINUES TO NEED MONITORING.
RAIN CHANCES MAY LINGER ACROSS PORTIONS OF THE CWA THROUGH THE
REMAINDER OF THE PERIOD AS MOISTURE WRAPS AROUND THE LOW AS IT
PROGRESSES SLOWLY EASTWARD. NORTHWESTERLY FLOW ALOFT ON THE
BACKSIDE OF THE UPPER-LEVEL CUTOFF WILL SUPPORT MORE SEASONABLE
AIR FILTERING INTO THE CWA BEHIND THE FRONT, WITH ENSEMBLE MEANS
HOVERING RIGHT AROUND CLIMATOLOGICAL NORMALS THROUGH THE END OF
THE WORKWEEK.
ELMORE
AVIATION
(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 558 PM CST THU DEC 8 2022
STRATUS AND OCCASIONAL DRIZZLE AND FOG ARE EXPECTED TO RESULT IN IFR
FLIGHT CONDITIONS AT ALL TERMINALS THROUGHOUT THE NIGHT AND INTO
FRIDAY MORNING. PASSING SHOWERS ARE ALSO EXPECTED AT TIMES,
PRIMARILY AT KUIN, BUT WILL HAVE LITTLE IMPACT GIVEN THE PREVAILING
IFR FLIGHT CONDITIONS. BRIEF VISIBILITIES BELOW 1SM CANNOT BE RULED
OUT WITH HEAVIER DRIZZLE AND DENSER FOG, BUT LOW CONFIDENCE IN
OCCURRENCE AND TIMING PRECLUDED ITS INCLUSION. A COLD FRONT IS
FORECAST TO TRAVERSE THE AREA FROM WEST TO EAST OVERNIGHT WITH
GRADUALLY VEERING WINDS, INITIALLY EASTERLY, VEERING MORE QUICKLY
FROM SOUTHERLY TO WESTERLY AT AND FOLLOWING ITS PASSAGE. IFR FOG AND
STRATUS, PERHAPS CONTINUED DRIZZLE, WILL LINGER BEHIND THE FRONT
BEFORE LIFTING AND CLEARING LATE MORNING/MIDDAY FRIDAY. CLEARING MAY
NOT OCCUR UNTIL MUCH LATER AT KUIN, BUT STRATUS SHOULD AT LEAST LIFT
TO MVFR DURING EARLY AFTERNOON.
PFAHLER
LSX WATCHES/WARNINGS/ADVISORIES
MO...NONE.
IL...NONE.
WFO LSX
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