803
FXUS63 KIND 171647
AFDIND
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
1147 AM EST TUE DEC 17 2024
KEY MESSAGES
- RAINFALL CHANCES RETURN TONIGHT INTO WEDNESDAY, WITH TOTAL QPF
AMOUNTS LESS THAN 1/2 AN INCH
- COOLER THAN NORMAL TEMPERATURES WILL BE AROUND LATER IN THE WEEK
THROUGH THE WEEKEND
- LIGHT SNOW POSSIBLE THURSDAY NIGHT INTO FRIDAY
FORECAST UPDATE
ISSUED AT 900 AM EST TUE DEC 17 2024
- MOSTLY SUNNY AND MILD
SURFACE ANALYSIS THIS MORNING SHOWS HIGH PRESSURE IN PLACE OVER
SOUTHERN IL AND WESTERN KY. THIS HIGH WAS PROVIDING WESTERLY SURFACE
FLOW TO CENTRAL INDIANA. THE HIGH WAS ALSO PROVIDING SUBSIDENCE AND
MOSTLY CLEAR SKIES ACROSS CENTRAL INDIANA. LOOKING ALOFT, A MAINLY
ZONAL FLOW WAS IN PLACE ACROSS CENTRAL INDIANA, EXTENDING WEST TO
THE HIGH PLAINS. AN UPPER LEVEL DISTURBANCE WAS EXITING THE ROCKIES,
PUSHING TOWARD THE PLAINS. THIS FEATURE WAS RESULTING IN SOME LIFT
ACROSS KS AND NB, AND WILL LEAD TO INCREASING CLOUD COVER THIS
EVENING ACROSS OUR AREA.
MODELS SUGGEST CONTINUED SUBSIDENCE ACROSS CENTRAL INDIANA AND ALSO
SHOW SOME MID LEVEL RIDGING DEVELOPING OVER INDIANA AS THE SYSTEM
OVER THE PLAINS BEGINS TO DEEPEN AS IT PUSHES EAST. FORECAST
SOUNDINGS SHOW THIS MID LEVEL DRYING THROUGH THE AFTERNOON AND KEEP
A DRY COLUMN ACROSS THE FORECAST AREA THROUGH THE EARLY EVENING.
THIS WILL LEAD TO A MOSTLY SUNNY DAY ACROSS CENTRAL INDIANA. HRRR
SUGGESTS HIGHS IN THE UPPER 40S TO AROUND 50, WITH MINIMAL
TEMPERATURE ADVECTION TODAY. OVERALL, ONGOING FORECAST REMAINS ON
TRACK.
SHORT TERM (TODAY AND TONIGHT)
ISSUED AT 304 AM EST TUE DEC 17 2024
TODAY:
SURFACE HIGH PRESSURE IS CONTINUING TO BUILD ACROSS THE REGION EARLY
THIS MORNING AS THE SOUTHERN GREAT LAKES FALL BENEATH MODERATE AVA.
THIS HAS LEAD TO CLEARING SKIES AND FAIRLY EFFICIENT DIURNAL
COOLING, WITH TEMPERATURES THIS MORNING FALLING 3-5 DEGREES BELOW
GUIDANCE. THE EXPECTATION IS FOR THIS TO BEGIN TO CURTAIL (NEARING
SATURATION) OVER THE NEXT FEW HOURS WITH LOWS JUST ABOVE FREEZING
FOR MOST OF THE I-70 CORRIDOR AND NORTHWARD. DURING DAYLIGHT HOURS,
WINDS WILL BEGIN TO VEER TOWARDS THE SE, AIDING DIURNAL WARMING
THROUGH WEAK WAA. THIS SHOULD RESULT IN WELL ABOVE NORMAL HIGHS THIS
AFTERNOON; CURRENT FORECAST IS UPPER 40S TO LOW 50S ACROSS CENTRAL
INDIANA. AS WE APPROACH DUSK, SOME MID LEVEL MOISTURE WILL BE
NEARING CENTRAL INDIANA FROM THE SW, THIS WILL LIKELY LEAD TO SOME
SCATTERED TO BROKEN CLOUD COVER.
TONIGHT:
MOISTURE WILL CONTINUE TO INCREASE EARLY TONIGHT AS LOW LEVEL WSW
FLOW STRENGTHENS. EVENTUALLY, THE 850-700MB LAYER WILL SATURATE
(WHERE MODEST LIFT IS EXPECTED) LEADING TO NUMEROUS SHOWERS. HREF
MEMBERS ARE BEGINNING TO SHOW SOME CONTINUITY, BUT QPF GUIDANCE IS
STILL VARIED, DESPITE ONLY 24 HOURS UNTIL PRECIPITATION ONSET.
GENERALLY, THE MAIN PRECIPITATION AXIS AND GREATEST LIFT IS EXPECTED
TO REMAIN SOUTH OF CENTRAL INDIANA, KEEPING TOTAL QPF BELOW 0.5"
(MOST AREAS BELOW 0.25") FOR THIS SYSTEM, OF WHICH WILL ALSO
INCLUDE A MODEST SOUTH TO NORTH QPF GRADIENT ACROSS CENTRAL IN.
WITH THAT SAID, 00Z HREF MEMBERS DISAGREE ON PRECIPITATION ONSET
AND COVERAGE TUESDAY NIGHT. GIVEN THE ANTECEDENT DRY AIRMASS, THE
CURRENT FORECAST FAVORS HREF MEMBERS THAT DEPICT LATER ONSET TIMES
AND A STEEPER COVERAGE GRADIENT FROM SOUTH TO NORTH. THE
EXPECTATION IS FOR LIGHT SHOWERS TO BEGIN BETWEEN 03-06Z ACROSS SW
CENTRAL INDIANA AND PUSH ENE THROUGH THE NIGHT.
THE LIFT IN THIS INITIAL PRECIPITATION WILL BE MOSTLY DUE TO A STRONG
AREA OF 850-700MB WAA AND ISENTROPIC LIFT. THIS AREA OF WAA IS
EXPECTED TO CREATE A ROBUST WARM NOSE, OF WHICH SHOULD KEEP ALL
PRECIPITATION AS RAIN DESPITE WETBULB SURFACE TEMPERATURES NEARING
FREEZING LATE TUESDAY NIGHT. IF SNOW DOES OCCUR, IT WOULD LIKELY BE
ASSOCIATED WITH THE MID LEVEL WAVE WEDNESDAY MORNING (DISCUSSED IN
THE LONG TERM SECTION).
LONG TERM (WEDNESDAY THROUGH MONDAY)
ISSUED AT 304 AM EST TUE DEC 17 2024
WEDNESDAY...
FORCING FROM THE UPPER IMPULSE TO THE SOUTH OF CENTRAL INDIANA WILL
DIMINISH WEDNESDAY MORNING AS THE IMPULSE MOVES OFF TO THE EAST.
MEANWHILE, AN UPPER TROUGH WILL MOVE IN FROM THE NORTHWEST. MOISTURE
THOUGH WILL BE MAINLY CONFINED TO THE MID LEVELS AS LOW LEVEL
MOISTURE IS TIED UP WITH THE IMPULSE TO THE SOUTH.
THE END RESULT WILL BE MAINLY CHANCE POPS ACROSS CENTRAL INDIANA
WEDNESDAY MORNING, WITH THE AFTERNOON DRY AS FORCING EXITS THE AREA.
TEMPERATURES WILL BE NEAR NORMAL.
WEDNESDAY NIGHT INTO THURSDAY...
QUIET WEATHER WILL CONTINUE ACROSS THE FORECAST AREA AS HIGH
PRESSURE MOVES THROUGH. TEMPERATURES WILL BE A LITTLE COOLER THAN
NORMAL.
THURSDAY NIGHT INTO FRIDAY...
A CLIPPER SYSTEM WILL MOVE INTO THE LOWER GREAT LAKES REGION DURING
THIS PERIOD, WITH AN UPPER TROUGH MOVING THROUGH ALOFT. BETTER
MOISTURE WILL BE CONFINED TO THE NORTHERN PART OF THE SYSTEM, AS IS
TYPICAL WITH CLIPPER SYSTEMS. WILL GO WITH SOME CHANCE POPS ACROSS
THE NORTHEASTERN TWO-THIRDS OF THE AREA OR SO.
TEMPERATURES WILL BE COLD ENOUGH FOR SNOW AS THE PRECIPITATION TYPE.
WITH MOST OF THE MOISTURE NORTH OF THE AREA, ANY SNOW ACCUMULATION
WOULD BE PRETTY LIGHT.
A LITTLE COOLER THAN NORMAL TEMPERATURES WILL CONTINUE.
SATURDAY THROUGH MONDAY...
SURFACE HIGH PRESSURE WILL BE IN CONTROL OF THE LOW LEVELS DURING
THIS PERIOD. SOME WEAK UPPER ENERGY WILL MOVE THROUGH ON SATURDAY,
BUT AT THE MOMENT FEEL THAT FORCING/MOISTURE WILL BE TOO LIMITED FOR
ANY PRECIPITATION. WILL GO DRY THROUGH THIS ENTIRE PERIOD.
COLDER AIR BROUGHT IN BEHIND FRIDAY'S CLIPPER WILL KEEP
TEMPERATURES BELOW NORMAL TEMPERATURES THROUGH THIS PERIOD.
MONDAY NIGHT AND BEYOND...
AN UPPER WAVE COULD BRING SOME PRECIPITATION MONDAY NIGHT INTO
TUESDAY, BUT CONFIDENCE IN THE DETAILS THAT FAR OUT IS LOW.
COLDER AIR LOOKS TO BE LOCKED UP TO THE NORTHWEST BY MID-WEEK NEXT
WEEK, MAKING FOR THE POTENTIAL OF A CHRISTMAS WITH ABOVE NORMAL
TEMPERATURES.
AVIATION (18Z TAF ISSUANCE)
ISSUED AT 1147 AM EST TUE DEC 17 2024
IMPACTS:
- MVFR THROUGH AT LEAST 06Z.
- MVFR WITH RAIN SHOWERS POSSIBLE AFTER 09Z, CONTINUING THROUGH 18Z
WEDNESDAY
DISCUSSION:
VFR CONDITIONS ARE EXPECTED THIS AFTERNOON AND EVENING AS HIGH
PRESSURE SOUTH OF INDIANA REMAINS IN CONTROL OF OUR WEATHER.
SUBSIDENCE ACROSS THIS AREA WILL LEAD TO MOSTLY CLEAR SKIES AS
FORECAST SOUNDINGS SHOW A DRY COLUMN THROUGH THE DAY.
TONIGHT, CLOUDS OVER THE PLAINS STATES ARE EXPECTED TO INVADE
CENTRAL INDIANA. THESE CLOUDS WILL BE AHEAD OF A DEEPENING SHORT
WAVE PUSHING OUT OF THE PLAINS TOWARD INDIANA. GOOD ISENTROPIC LIFT
ARRIVES ACROSS THE FORECAST AREA AFTER 09Z. THIS SHOULD LEAD TO SOME
MVFR CIGS AMID SOME RAIN SHOWERS. BEST CHANCES FOR RAIN SHOWERS WILL
BE FOUND ACROSS THE SOUTHERN TAF SITES, BMG, AS THE BEST LIFT WILL BE
FOUND THERE.
COLD AIR ADVECTION IN THE WAKE OF THE DEPARTING SYSTEM WILL LEAD TO
CONTINUED MVFR STRATOCU CIGS ON WEDNESDAY AFTERNOON.
IND WATCHES/WARNINGS/ADVISORIES
NONE.
UPDATE...PUMA
SHORT TERM...UPDIKE
LONG TERM...50
AVIATION...PUMA
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