344
FXUS63 KLOT 010522
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE, IL
1222 AM CDT THU JUN 1 2023
SHORT TERM
ISSUED AT 304 PM CDT WED MAY 31 2023
THROUGH THURSDAY NIGHT...
THUNDERSTORMS CONTINUE TO DEVELOP ACROSS MUCH OF NORTHEASTERN AND
CENTRAL ILLINOIS THIS AFTERNOON AND ARE EXPECTED TO LINGER
THROUGH EARLY EVENING. WHILE INSTABILITY IS MORE THAN SUFFICIENT
(AROUND 1000 J/KG MLCAPE AND 9+ C/KM LOW-LEVEL LAPSE RATES), THE
LACK OF SYNOPTIC SCALE FORCING HAS CONFINED THE THUNDERSTORM
ACTIVITY TO A VARIETY OF MESOSCALE SURFACE BOUNDARIES (LAKE BREEZE
AND OUTFLOW) SCATTERED ACROSS THE AREA. THE EXPECTATION IS FOR
STORMS TO CONTINUE TO PULSE ALONG THESE BOUNDARIES INTO THE EARLY
EVENING HOURS WHERE THE WANING INSTABILITY SHOULD ALLOW CONVECTION
TO FINALLY COME TO AN END. GIVEN THAT THESE BOUNDARIES ARE FLUID,
THE COVERAGE OF STORMS WILL CONTINUE TO BE OF AN ISOLATED TO
WIDELY SCATTERED NATURE MEANING THAT SOME AREAS MAY NOT SEE RAIN.
HOWEVER, ANY AREAS THAT DO SEE STORMS COULD SEE PERIODS OF HEAVY
RAINFALL AND POSSIBLY SOME SMALL HAIL AND/OR GUSTY WINDS UPWARDS
OF 40 MPH ESPECIALLY FROM MORE ROBUST CORES. REGARDLESS,
WIDESPREAD SEVERE WEATHER IS NOT EXPECTED GIVEN THE AFOREMENTIONED
LACK OF UPPER-LEVEL DYNAMICS AND WIND SHEAR.
ONCE STORMS FIZZLE THIS EVENING, DRY AND CLEARING CONDITIONS ARE
EXPECTED FOR TONIGHT WITH TEMPERATURES DROPPING INTO THE MID-60S.
TEMPERATURES WILL ONCE AGAIN WARM INTO THE UPPER 80S TO LOWER 90S
ON THURSDAY WITH PARTLY CLOUDY SKIES. CHANCES FOR STORMS ARE
EXPECTED TO MATERIALIZE THURSDAY AFTERNOON GIVEN THE SIMILAR
ENVIRONMENT TO TODAY, HOWEVER; DRIER AIR IS EXPECTED TO BE
ADVECTING INTO THE AREA FROM THE EAST. THIS DRY ADVECTION SHOULD
HELP KEEP THUNDERSTORM ACTIVITY CONFINED TO AREAS NEAREST THE I-39
CORRIDOR WHERE BETTER MOISTURE AND SOME UPPER-LEVEL INFLUENCE IS
FORECAST TO ESTABLISH. REGARDLESS, I HAVE MAINTAINED AN ISOLATED
TO SCATTERED MENTION OF STORMS FOR THE ENTIRE REASON GIVEN THIS
POTENTIAL BUT SUSPECT THAT EASTWARD EXTENT SHOULD BE SOMEWHAT
LIMITED. ANY STORMS THAT DO DEVELOP ON THURSDAY ARE EXPECTED TO
TAPER DURING THE EARLY EVENING AS INSTABILITY WANES LEAVING US
WITH DRY CONDITIONS OVERNIGHT ONCE AGAIN.
YACK
LONG TERM
ISSUED AT 304 PM CDT WED MAY 31 2023
FRIDAY THROUGH WEDNESDAY...
KEY FORECAST MESSAGES:
* VERY WARM/HOT INLAND FRIDAY THROUGH THE WEEKEND BUT WITH LOWER
HUMIDITY LEVELS
* CONTINUATION OF THE PRIMARILY DRY PATTERN
ON FRIDAY, DRIER EASTERLY LOW LEVEL FLOW UP TO 850 MB AND INLAND
FOOTPRINT OF DRYING INFLUENCE OF HIGH PRESSURE CENTERED OVER THE
GREAT LAKES WILL SHUNT THE INSTABILITY AXIS WELL INLAND AND LIKELY
PRECLUDE THE THREAT FOR ANY SHOWERS OUTSIDE OF THE CWA. LIMITED
ANY SLIGHT CHANCE POPS TO FAR INTERIOR SECTIONS AND WITH THE
THUNDER THREAT LOOKING EVEN LOWER THAN THE CHANCE FOR MEASURABLE
RAIN, REMOVED THUNDER MENTION FROM THE GRIDDED DATABASE. THE MAIN
STORY WILL BE THE HOT TEMPERATURES INLAND, REACHING THE LOWER TO
LOCALLY MID 90S. SAVING GRACE WILL BE LOWER HUMIDITY LEVELS, AS
DEW POINTS MIX OUT THE UPPER 40S AND LOWER 50S DURING THE AFTERNOON.
LAKESIDE LOCALES WILL REACH THE LOWER TO MID 70S THANKS TO ONSHORE
FLOW THROUGH THE DAY.
SATURDAY WILL BE QUITE SIMILAR TO FRIDAY TEMPERATURE WISE, EXCEPT
WITH NO PRECIP. CHANCES EVEN FAR INLAND AND SOMEWHAT STRONGER
NORTHEAST FLOW, POSSIBLY FEATURING GUSTS UP TO 20 TO 25 MPH. THE
SEMI-PERMANENT REX BLOCK PATTERN WILL THEN RETURN INTO NEXT WEEK
AS A CLOSED UPPER LOW PARKS OVER THE NORTHEAST. GRADUAL "COOL"
ADVECTION EMANATING FROM THE HUDSON BAY TO GREAT LAKES SURFACE
HIGH WILL BRING SLIGHTLY LOWER TEMPERATURES SUNDAY, AND ESPECIALLY
NEXT WORK WEEK, THOUGH INLAND HIGHS SHOULD STILL GENERALLY AVERAGE
ABOVE NORMAL. OVERNIGHTS WILL GO FROM MILD TO COMFORTABLY COOL
OUTSIDE OF CHICAGO LATER IN THE WEEKEND INTO NEXT WEEK.
UNFORTUNATELY FOR AREAS THAT MISS OUT ON THE POP-UP CONVECTION
TODAY (WEDNESDAY) AND THURSDAY, THERE'S LITTLE HOPE FOR MEANINGFUL
DROUGHT RELIEF THROUGH DAY 7 (NEXT WEDNESDAY). OTHER THAN MAYBE A
FEW SPOTTY DIURNAL SHOWERS WITH A BACKDOOR FRONT SOMETIME IN THE
TUESDAY-WEDNESDAY TIMEFRAME, DRY CONDITIONS WILL PREVAIL.
LONGER RANGE PATTERN GUIDANCE OFFERS *SOME* HOPE OF A MORE ACTIVE
PATTERN ARRIVING BY MID JUNE, BUT UNTIL THEN, EXPECT DROUGHT
CONDITIONS TO WORSEN FOR MOST AREAS.
CASTRO
AVIATION
FOR THE 06Z TAFS...
1222 AM...FORECAST CONCERNS INCLUDE...
CHANCE OF THUNDERSTORMS THIS AFTERNOON.
LAKE BREEZE/WIND DIRECTIONS THIS AFTERNOON.
ISOLATED THUNDERSTORMS WILL BE POSSIBLE AGAIN THIS AFTERNOON,
LIKELY AIDED BY A LAKE BREEZE. CONFIDENCE IS LOW REGARDING
COVERAGE, WHICH MAY END UP LESS THAN ON WEDNESDAY AFTERNOON. BUT
INSTABILITY IS SUFFICIENT FOR ANYTHING THAT DOES FORM TO HAVE
THUNDER AND INCLUDED PROB THUNDER MENTION FOR ALL THE TERMINALS.
THERE MAY BE A BETTER CHANCE FOR THUNDERSTORMS TO PROPAGATE
INLAND BY MID/LATE AFTERNOON, WITH A POSSIBLE SHORTER DURATION AT
ORD/MDW. ANY STORMS THAT FORM WILL LIKELY PRODUCE OUTFLOW
BOUNDARIES, MAKING FOR PROBLEMATIC AND SHIFTING WIND DIRECTIONS.
PREVAILING LIGHT SOUTHEAST WINDS OVERNIGHT WILL INCREASE TOWARD
10KTS LATER THIS MORNING, WITH THE LAKE BREEZE TURNING WINDS MORE
EASTERLY FOR ORD/MDW/GYY. WIND DIRECTIONS WILL SETTLE TO LIGHT
EAST/NORTHEAST THIS EVENING. CMS
LOT WATCHES/WARNINGS/ADVISORIES
IL...NONE.
IN...NONE.
LM...NONE.
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