100
FXUS63 KPAH 151721 AAA
AFDPAH
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PADUCAH KY
1121 AM CST SUN DEC 15 2024
KEY MESSAGES
- THE NEXT ROUND OF WIDESPREAD MODERATE TO HEAVY RAINFALL MOVES
THROUGH LATE TONIGHT INTO MONDAY WITH ANOTHER 0.5 TO 1.5 INCHES
OF RAINFALL. A STRONGER STORM WITH SMALL HAIL IS POSSIBLE
MONDAY MORNING IN SOUTHEAST MISSOURI.
- AFTER A DRY DAY ON TUESDAY, MORE RAIN MOVES THROUGH TUESDAY
NIGHT INTO WEDNESDAY. ANOTHER 0.5 TO 1.0 INCHES OF RAINFALL
IS POSSIBLE.
- AN ARCTIC COLD FRONT MOVES THROUGH WEDNESDAY NIGHT.
TEMPERATURES WILL PLUMMET AND REMAIN BELOW NORMAL THROUGH NEXT
WEEKEND, WITH WIND CHILL VALUES FALLING INTO THE TEENS. A FEW
SNOW FLURRIES MAY EVEN RETURN FRIDAY AS AN ALBERTA CLIPPER
PASSES BY TO THE NORTH.
DISCUSSION
ISSUED AT 243 AM CST SUN DEC 15 2024
GOES-16 SATELLITE IMAGERY SHOWS A VERTICALLY STACKED LOW NOW LIFTING
NORTHEAST ACROSS ILLINOIS THIS MORNING AS THE LAST BROKEN LINE OF
SHOWERS IS NOW BEGINNING TO EXIT PORTIONS OF SOUTHWEST INDIANA AND
WESTERN KENTUCKY. LINGERING AREAS OF DRIZZLE WILL CONTINUE TO REMAIN
POSSIBLE ALONG AND EAST OF I-57 THROUGH THIS MORNING AS THE BOUNDARY
LAYER REMAINS SATURATED. IN THE MID-LEVELS, WATER VAPOR SHOWS
THE DRY-CONVEYOR BELT ADVECTING IN AS THE REST OF TODAY WILL END
UP BEING A RELATIVELY DRY DAY WITH A WEAK RIDGE AXIS BUILDING
ALOFT. HOWEVER, THERE WILL BE ENOUGH OF INVERSION TO KEEP A LOW
STRATUS DECK IN PLACE FOR MOST OF THE DAY WITH THE EXCEPTION OF
MAYBE THE FAR NW WHERE SOME BREAKS OF SUN ARE MORE LIKELY. HIGH
TEMPS WILL BE MILDER IN THE UPPER 50S TO NEAR 60.
A HIGHLY PROGRESSIVE SYNOPTIC FLOW ALOFT MEANS THE NEXT CHANCE OF
UNSETTLED WEATHER QUICKLY ARRIVES TONIGHT AS ANOTHER SHORTWAVE
TROUGH DIGS SOUTHEAST FROM THE NORTHERN PLAINS. WHILE THE BETTER
LARGE- SCALE FORCING AT 500 MB WILL BE WELL TO THE NORTHEAST, A
LEADING SUBTLE IMPULSE COMBINED WITH SOME BETTER FORCING AT 850 MB
WILL CAUSE A CLUSTER OF SHOWERS AND EMBEDDED ELEVATED
THUNDERSTORMS TO DEVELOP LATE TONIGHT INTO MONDAY MORNING FROM
SOUTHWEST TO NORTHEAST. MEANWHILE, PWATS MAY NOW NEAR 1.5 INCHES,
WHICH IS ABOUT 3 STANDARD DEVIATIONS ABOVE NORMAL. WHILE THE HREF
IS SHOWING ABOUT A 60% PROBABILITY OF GREATER THAN 1 INCH OF
RAINFALL OVER A 3 HOUR PERIOD, FFG REMAINS ABOVE 2 INCHES FOR MOST
AREAS DESPITE THE POTENTIAL FOR TORRENTIAL DOWNPOURS. AT MOST,
SOME RUNOFF WILL BE POSSIBLE IN MORE PRONE LOCATIONS, BUT OVERALL
THE FLOODING RISK REMAINS LOW. ADDITIONAL TOTAL QPF BETWEEN 0.5 TO
1.5 INCHES IS EXPECTED.
AS FOR THE LOW CONDITIONAL SEVERE RISK THAT HAS PREVIOUSLY BEEN
MENTIONED, THE THERMODYNAMICS LOOK ABOUT THE SAME WITH THE
HRRR/RAP SUPPORTING ABOUT 400-700 J/KG OF MUCAPE, IN LINE WITH
WHAT THE ECMWF HAS BEEN ADVERTISING THE LAST COUPLE OF DAYS.
MID-LEVEL LAPSE RATES ARE STILL ABOUT 6.5-7.0 C/KM AT BEST AS
MODEST HEIGHT FALLS CAUSES SOME COOLING ALOFT. WHILE THE SFC
PARAMETERS ARE STILL LACKING DUE TO A CAPPING INVERSION JUST
ABOVE THE SFC, 25 KTS OF EFFECTIVE BULK SHEAR IS ENOUGH TO
SUPPORT AT LEAST ISOLATED SMALL HAIL IN SOUTHEAST MISSOURI. IF
MOISTURE AND INSTABILITY WERE TO SLIGHTLY OVERACHIEVE, A
STRONGER STORM WOULD NOT BE OUT OF THE QUESTION. FOR NOW, THE
SEVERE RISK STILL REMAINS FAIRY MUTED WITH "GENERAL THUNDER"
PROGGED BY THE SPC IN THEIR D1/D2 CONVECTIVE OUTLOOK.
WHILE INSTABILITY WANES BY MONDAY AFTERNOON, A LINE OF SHOWERS
WITH EMBEDDED RUMBLES OF THUNDER WILL CONTINUE EAST OF THE
MISSISSIPPI BEFORE EXITING MONDAY EVENING. IN THE WAKE OF A
COLD FRONT MONDAY NIGHT, HIGH TEMPS WILL BE UNSEASONABLY WARM IN
THE LOW TO MID 60S. COOLER AND DRIER CONDITIONS CAN BE EXPECTED
TUESDAY WITH HIGHS IN THE LOW TO MID 50S AS HIGH PRESSURE
BUILDS OVER THE REGION. ANOTHER TROUGH THEN DIGS ACROSS THE
PLAINS TUESDAY NIGHT AS WAA AND ISENTROPIC LIFT ALLOWS FOR
ANOTHER ROUND OF RAIN TO DEVELOP INTO THE DAY WEDNESDAY. AT THE
MOMENT, PCPN WILL BE QUICK TO EXIT WEDNESDAY AFTERNOON BEFORE
MUCH COLDER AIR ARRIVES AS A MORE POTENT COLD FRONT WILL BE
QUICK TO MOVE THROUGH. ADDITIONAL QPF IS PROGGED BETWEEN 0.5 TO
1.0 INCHES OF RAINFALL. HIGHS AGAIN WILL BE IN THE LOW TO MID
50S, FOLLOWED BY THE FIRST OF MANY FREEZING NIGHTS WITH LOW
TEMPS PLUMMETING INTO THE 20S DUE TO STRONG CAA.
THE PATTERN REMAINS HIGHLY TRANSIENT AS RISING HEIGHTS THURSDAY
QUICKLY GIVE WAY TO ANOTHER TROUGH THURSDAY NIGHT INTO FRIDAY.
BOTH THE GFS/ECMWF SHOW AN ALBERTA CLIPPER MOVING ACROSS THE
GREAT LAKES REGION FRIDAY MORNING THAT WILL REINFORCE TRUE
ARCTIC COLD AIR FOR THE UPCOMING WEEKEND. ALTHOUGH THE CLIPPER
MAY BE TOO FAR NORTH, THE NBM IS NOT PICKING UP ON THE
POTENTIAL FOR FLURRIES OR LIGHT SNOW SHOWERS FRIDAY INTO FRIDAY
EVENING. A TRAILING VORT MAX SHOULD SUPPORT SOME PRETTY STEEP
LOW-LEVEL LAPSE RATES WITH THE 1000-500MB THICKNESS LINES
FALLING BELOW 540. WITH THAT SAID, THE COLD BLAST STILL LOOKS
FAIRLY SIGNIFICANT WITH 850 MB TEMPS AROUND -5 TO -10C OVER THE
WEEKEND. HIGHS TEMPS IN THE 40S THURSDAY AND FRIDAY MAY STRUGGLE
TO REACH 40 OVER THE WEEKEND FOR THIS REASON, WITH LOW TEMPS
REMAINING WELL INTO THE 20S. WIND CHILL VALUES STILL LOOK TO
FALL INTO THE TEENS, AND POSSIBLY THE SINGLE DIGITS.
AVIATION /18Z TAFS THROUGH 18Z MONDAY/
ISSUED AT 1121 AM CST SUN DEC 15 2024
FOG CONDITIONS ARE SLOWLY IMPROVING OVER MISSOURI AND MOSTLY LOW
MVFR CIGS ARE FORMING UP. FURTHER EAST LOW MVFR CLOUD DECKS ARE
MORE BROKEN TO SCATTERED. A FEW HOURS OF VFR CONDITIONS ARE
POSSIBLE AT VARIOUS SITES AND TIMES BUT THE OVERALL THEME WILL
BE FOR AT LEAST SCATTERED CLOUDS AT 1200-2200 FT.
AFTER SUNSET MORE UNSETTLED CONDITIONS BEGIN TO MOVE BACK INTO
THE AREA. PREVAILING LOW MVFR/IFR CEILINGS WITH VISIBILITY
REDUCING IN RAIN AND MIST CAN BE EXPECTED AREA-WIDE ONCE THIS
SETS IN. AREAS OF HEAVIER RAIN AND THUNDERSTORMS ARE ALSO
EXPECTED AT TIMES WITH THIS ACTIVITY. LOW-LEVEL WIND SHEAR
CONDITIONS WILL ALSO BE POSSIBLE WITH SOUTHWESTERLY WINDS AT
2000-3000 FT EXPECTED TO BE NEAR 50 KTS FOR A FEW HOURS IN THE
OVERNIGHT.
A FRONT THEN MOVES TOWARDS THE AREA AFTER SUNRISE MONDAY BUT AT
LEAST FOR NOW IFR CEILINGS LOOK TO PERSIST ALONG AND BEHIND THE
FRONT THROUGH THE NEW TAF PERIOD.
PAH WATCHES/WARNINGS/ADVISORIES
IL...NONE.
MO...NONE.
IN...NONE.
KY...NONE.
DISCUSSION...DW
AVIATION...JGG
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