191
FXUS63 KIND 201131
AFDIND
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
631 AM EST SAT DEC 20 2025
KEY MESSAGES
- WIND GUSTS BETWEEN 30-40 MPH LATER THIS MORNING INTO THE
AFTERNOON.
- MODERATING PATTERN THROUGH THE MIDDLE OF NEXT WEEK WITH
UNSEASONABLY MILD CONDITIONS EXPECTED WEDNESDAY-FRIDAY
- NEAR RECORD HIGH TEMPERATURES IN THE 60S POSSIBLE ON CHRISTMAS DAY.
SHORT TERM (TODAY AND TONIGHT)
ISSUED AT 300 AM EST SAT DEC 20 2025
A STRONG VORT MAX IS CURRENTLY MOVING EASTWARD WITHIN ZONAL UPPER-
LEVEL FLOW OVER THE NORTHERN GREAT LAKES. ITS CORRESPONDING SURFACE
CYCLONE IS POTENT, AT ROUGHLY 990MB. THIS SYSTEM IS MODELED TO RACE
EASTWARD TODAY, DRAGGING A COLD FRONT ACROSS INDIANA THIS EVENING.
SURFACE HIGH PRESSURE THEN BUILDS IN BRINGING QUIET WEATHER TONIGHT
INTO SUNDAY.
BEFORE THAT HAPPENS, HOWEVER, STRONG MASS RESPONSE HAS ALLOWED A
POTENT LOW-LEVEL JET TO FORM. THIS JET, SITUATED AT 925 TO 850 MB,
WILL RAPIDLY BRING WARM AIR BACK NORTHWARD THROUGH THE MORNING AND
AFTERNOON. DESPITE AN ARCTIC FRONT PASSING BY ONLY 24 TO 36 HOURS
AGO, WE'LL SEE HIGHS CLIMB QUICKLY INTO THE 40S AND LOW 50S.
ADDITIONALLY, SOME GUSTY WINDS ARE POSSIBLE TODAY AS WEAK MIXING
ALLOWS SOME OF THE MOMENTUM ASSOCIATED WITH THE LLJ TO MIX DOWNWARD.
MODEL SOUNDINGS SHOW A FAIRLY SHALLOW PBL AND WARM NOSE ALOFT, SO
WIND GUSTS WILL BE LIMITED DESPITE THE STRONG (50-60KT) LLJ JUST
ABOVE THE SURFACE. STILL, A TIGHT MSLP GRADIENT AT THE SURFACE
SHOULD PROMOTE GUSTS BETWEEN 25-35KT AT TIMES UNTIL THE COLD FRONT
ARRIVES DURING THE AFTERNOON.
VERY LITTLE MOISTURE ADVECTION IS SHOWN IN GUIDANCE, THOUGH DEW
POINTS SHOULD GRADUALLY PUSH INTO THE LOW/MID 30S DURING THE
AFTERNOON. ALL THE BEST FORCING ASSOCIATED WITH THE TROUGH/LOW WILL
PASS FAR TO OUR NORTHEAST. THUS, NO PRECIPITATION IS EXPECTED TODAY.
BY TONIGHT, THE COLD FRONT IS EXPECTED TO PASS THROUGH BETWEEN 00Z-
06Z. COOLER AIR WILL SLOWLY SEEP SOUTHWARD BEHIND THE FRONT,
ALLOWING FOR LOWS IN THE 20S (LOW 20S NORTH, UPPER 20S SOUTH).
LONG TERM (SUNDAY THROUGH FRIDAY)
ISSUED AT 319 AM EST SAT DEC 20 2025
BELLY OF H500 ZONAL TROUGH TO SLIDE EAST ACROSS THE MIDWEST SUNDAY
WITH CORRESPONDING SURFACE POLAR HIGH PRESSURE KEEPING A QUICKER
PACE WHILE CROSSING THE CWA THROUGH THE LATTER HALF OF THE WEEKEND.
DRY AND MOSTLY CLEAR CONDITIONS AMID LIGHTER BREEZES WILL OVERSEE
NEAR TO SLIGHTLY BELOW NORMAL TEMPERATURES INTO SUNDAY NIGHT.
PROGRESSIVE PATTERN WILL SEND NEXT, WEAKER, AREA OF SURFACE LOW
PRESSURE ACROSS NORTHERN PLAINS/GREAT LAKES MONDAY INTO MONDAY
NIGHT...PLACING INDIANA WITHIN A LESS INTENSE GRADIENT OF VEERING
SOUTHERLY BREEZES, BRINGING MILDER CONDITIONS AND SCATTERED
DRIZZLE/LIGHT RAIN SHOWERS FOR MOST LOCATIONS.
THE MIDDLE OF THE LONG TERM WILL FEATURE A BROAD AND BUILDING UPPER
LEVEL RIDGE THAT WILL TREND MID-WEEK HIGHS UPWARD THROUGH THE 50S
INTO POSSIBLY THE 60S ON CHRISTMAS DAY. FURTHER CHANCES FOR
OCCASIONAL ISOLATED/SCATTERED RAIN SHOWERS WITH LOW-LEVEL FLOW MOST
OFTEN FROM A SOUTHERLY HEADING AROUND 10-20 MPH...WITH COVERAGE
OF SHOWERS LIKELY GREATEST AROUND THE LATE WEDNESDAY/WEDNESDAY
NIGHT TIMEFRAME WHEN DEEP MOISTURE OVER 1.00 INCH OF PRECIPITABLE
WATER WILL BE MOST PREVALENT. LIKELY A DOWNWARD TREND IN POPS
AROUND CHRISTMAS DAY WHEN THE UPPER RIDGE'S HEIGHTS AND ASSOCIATED
DIFFERENTIAL NVA ARE MOST LIKELY PEAKING. NEAR RECORD HIGH AND
LOW READINGS ARE POSSIBLE ON CHRISTMAS DAY.
SEASONABLY STRONG DOME OF POLAR SURFACE HIGH PRESSURE TO GRACE THE
NORTH-CENTRAL US WITH ITS SOUTHERN QUADRANTS BY THE END OF THE
WORKWEEK/PERIOD, BRINGING A MORE SEASONABLE TREND THAT SHOULD EQUATE
TO SLIGHTLY ABOVE NORMAL READINGS. ADEQUATE DEEP GULF MOISTURE AND
UNSEASONABLY HIGH SURFACE THETA-E VALUES WILL PROMOTE AT LEAST
SCATTERED RAIN SHOWERS, ALTHOUGH APPEARS UPSTREAM ZONAL UPPER
PATTERN WOULD NOT SUPPORT ANY SUBSTANTIVE INSTABILITY. THE NORMAL
MAX/MIN AT INDIANAPOLIS THROUGH THE LONG TERM ARE 38/24.
AVIATION (12Z TAF ISSUANCE)
ISSUED AT 631 AM EST SAT DEC 20 2025
IMPACTS:
- LOW LEVEL WIND SHEAR THIS MORNING.
- GUSTY S/SW WINDS PEAKING BETWEEN 25 AND 30KT THIS MORNING INTO
THE AFTERNOON.
- WIND SHIFT TO NW AROUND 00Z.
DISCUSSION:
PASSING HIGH AND SOME MID CLOUDS WILL CONTINUE THROUGH THE PERIOD.
A STRONG LOW-LEVEL JET IS DEVELOPING WHICH WILL CAUSE A PERIOD OF
LOW-LEVEL WIND SHEAR BETWEEN 45-50KT. SHEAR WILL PERSIST INTO THE
MORNING HOURS.
SURFACE WINDS ARE CURRENTLY OUT OF THE SOUTHEAST, BUT WILL
GRADUALLY BECOME SOUTHWESTERLY AND THEN WESTERLY THIS AFTERNOON.
SOME GUSTS NEAR 25KT WILL BE COMMON AFTER ABOUT 16Z WITH PERHAPS A
GUST TO 30KT POSSIBLE.
A COLD FRONT IS EXPECTED TO ARRIVE AROUND 00Z, WHICH WILL CAUSE
WINDS TO BECOME NORTHWESTERLY. SPEEDS MAY INCREASE A BIT BEHIND THE
FRONT, BUT SHOULD GRADUALLY DIMINISH AFTER 06Z AS SURFACE HIGH
PRESSURE MOVES IN.
IND WATCHES/WARNINGS/ADVISORIES
NONE.
SHORT TERM...ECKHOFF
LONG TERM...AGM
AVIATION...ECKHOFF
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