143
FXUS63 KIND 181503
AFDIND
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
1003 AM EST THU DEC 18 2025
KEY MESSAGES
- WIDESPREAD RAIN LIKELY TODAY WITH QPF AMOUNTS GENERALLY RANGING
FROM 0.25 TO 0.75 INCHES.
- WIND GUSTS UP TO 40 MPH POSSIBLE TODAY AND TONIGHT, SLIGHTLY
HIGHER GUSTS UP TO 45 MPH CANNOT BE RULED OUT DURING THE
AFTERNOON.
- SLICK/ICY SPOTS LIKELY FRIDAY MORNING AS TEMPERATURES DROP QUICKLY
BELOW FREEZING.
- SNOW SHOWERS AT TIMES LATE TONIGHT INTO THE EARLY MORNING HOURS ON
FRIDAY.
- WIND CHILLS INTO THE SINGLE DIGITS POSSIBLE FRIDAY MORNING.
FORECAST UPDATE
ISSUED AT 1002 AM EST THU DEC 18 2025
THE FORECAST REMAINS IN GOOD SHAPE WITH ONLY MINOR ADJUSTMENTS MADE
TO POPS AND SKY COVER TO MATCH OBSERVATIONS. CURRENT SURFACE ANALYSIS
DEPICTS A STRONG SURFACE LOW CENTERED NEAR NORTHEAST PORTIONS OF
MINNESOTA WHILE AN ASSOCIATED COLD FRONT STRETCHES SOUTH TOWARDS THE
OZARKS AND EVEN TO LOCATIONS FURTHER SOUTHWEST. INCREASING WARM AIR
ADVECTION IS PROMOTING SCATTERED SHOWERS AT THIS TIME, PRIMARILY
FOCUSED OVER SOUTH-CENTRAL INDIANA. THESE SHOWERS WILL CONTINUE TO
PUSH NORTHEASTWARD OVER THE NEXT FEW HOURS.
LOOK FOR MORE WIDESPREAD PRECIPITATION THIS AFTERNOON THROUGH THE
EARLY EVENING HOURS ONCE THE AFOREMENTIONED COLD FRONT APPROACHES
ALONG WITH STRONGER MID-UPPER LEVEL FORCING. A TIGHTENING PRESSURE
GRADIENT AND INTENSE LLJ MOVING ACROSS INDIANA WILL ALSO PROMOTE
STRONG WIND GUSTS BETWEEN 35-45 MPH. LATEST HREF STILL SHOWS A VERY
HIGH POTENTIAL FOR WIND GUSTS AROUND OR SLIGHTLY HIGHER THAN 45 MPH,
BUT CAMS ARE LIKELY TOO BULLISH REGARDING DIURNAL MIXING.
FORECAST SOUNDINGS MOSTLY SHOW VERY MARGINAL MIXING LATER TODAY DUE
TO EXTENSIVE CLOUDS LIMITING DESTABILIZATION. WHILE THE HREF DOES
APPEAR TO BE BULLISH, UPSTREAM TRENDS WILL BE MONITORED CLOSELY
OVER THE NEXT FEW HOURS IN CASE A WIND ADVISORY IS WARRANTED.
WINDY CONDITIONS ARE LIKELY EITHER WAY TODAY. THE STRONGEST WINDS
MAY OCCUR WITH AN EXPECTED ORGANIZED LINE OF SHOWERS ALONG THE
APPROACHING COLD FRONT LATER TODAY WHICH COULD HELP TRANSFER
STRONGER WINDS ALOFT TO THE SURFACE.
SHORT TERM (TODAY AND TONIGHT)
ISSUED AT 308 AM EST THU DEC 18 2025
STRONG SURFACE LOW PRESSURE, ROUGHLY 984MB, OVER NORTH DAKOTA WILL
MOVE EASTWARD TODAY. STRONG SOUTHERLY FLOW AHEAD OF THE APPROACHING
LOW WILL DRIVE A POTENT LOW-LEVEL JET (LLJ) NORTHWARD. STRONG WARM
AIR AND MOISTURE ADVECTION ARE ONGOING, WITH STRATUS STREAMING IN
FROM THE SOUTH AS OF 2AM. TWO COLD FRONTS EXTEND SOUTH FROM THE LOW,
BOTH OF WHICH WILL MOVE ACROSS INDIANA WITH DIFFERENT ASSOCIATED
IMPACTS.
RAINFALL...
DESPITE THE LOW PASSING WELL TO OUR NORTH, ROUGHLY ACROSS LAKE
SUPERIOR, STRONG LARGE-SCALE FORCING WILL BE PRESENT FROM THE
SYSTEM'S PARENT TROUGH. COMBINED WITH ISENTROPIC ASCENT, WIDESPREAD
SHOWER ACTIVITY IS EXPECTED TO DEVELOP LATER THIS MORNING INTO THE
AFTERNOON. THE FIRST OF THE TWO AFOREMENTIONED COLD FRONTS WILL HELP
FOCUS THIS PRECIPITATION INTO A RELATIVELY NARROW BAND. HEAVY
RAINFALL RATES ARE LIKELY AS THIS BAND PASSES THROUGH ALONG WITH THE
POTENTIAL FOR A RUMBLE OR TWO OF THUNDER. RAINFALL TOTALS FROM 0.25"
TO ABOUT 0.75" ARE MOST PROBABLE. FLOODING IS NOT EXPECTED, GIVEN
THE GENERALLY MODEST RAINFALL TOTALS AND FAST-MOVING NATURE OF THE
HEAVIEST RAIN BAND.
ADDITIONALLY, THE BAND MAY PROVIDE ENOUGH DOWNWARD MOMENTUM TO BRING
SOME OF THE STRONG LLJ WINDS TO THE SURFACE. A FEW WIND GUSTS OVER
40KT WOULD NOT BE OUT OF THE QUESTION IF THIS WERE TO HAPPEN.
WINDS...
ONE OF THE MORE CHALLENGING PART OF TODAY'S FORECAST WILL BE SURFACE
WIND POTENTIAL THIS MORNING AND AFTERNOON. WITH A STRONG (UP TO 60KT
AT 925MB) LLJ JUST ABOVE THE SURFACE, ANY MIXING WOULD BE ENOUGH TO
BRING STRONG WIND GUSTS TO THE SURFACE. HOWEVER, MODEL SOUNDINGS ALL
SHOW FAIRLY STABLE LOW-LEVELS WHICH MAY LIMIT SUCH MIXING. MODEL
SOUNDINGS DESTABILIZE SOMEWHAT DURING THE COURSE OF THE DAY WHICH
MAY ALLOW MECHANICAL MIXING TO OVERCOME RESIDUAL BOUNDARY LAYER
STABILITY.
FOR NOW, WE'LL SPLIT THE DIFFERENCE AND RAISE WIND GUSTS FROM
BLENDED GUIDANCE TO AROUND 35-40KT. THIS PUTS GUSTS JUST BELOW
ADVISORY THRESHOLDS, WHICH MAY BE NEEDED LATER IF OBSERVATIONS SHOW
A TREND TOWARDS GREATER MIXING. UNDER SUCH A SCENARIO, A FEW WIND
GUSTS TO 45KT MAY BE POSSIBLE AT TIMES.
SNOW AND ARCTIC AIR...
THE FIRST COLD FRONT CLEARS THE AREA BY AROUND 00Z, WITH COOLER AIR
FLOWING IN FROM THE WEST. THE AIR MASS BEHIND THE FIRST FRONT IS NOT
THE ARCTIC AIR MASS, WITH TEMPERATURES FALLING FROM THE LOW 50S INTO
THE UPPER 30S. THE SECOND FRONT IS NOT FAR BEHIND, HOWEVER, ARRIVING
ACROSS OUR NORTHWEST AS EARLY AS 03Z. STRONG COLD AIR ADVECTION
QUICKLY PUSHES TEMPERATURES BELOW FREEZING, AND THEN DOWNWARD INTO
THE TEENS BY SUNRISE FRIDAY. GUSTY WINDS RETURN AS WELL WHICH MAY
RESULT IN WIND CHILL VALUES INTO THE SINGLE DIGITS FRIDAY MORNING.
SLICK/ICY SPOTS ARE LIKELY AS ANY WATER REMAINING ON ROADWAYS
QUICKLY FREEZES.
GUIDANCE SHOWS LOW-LEVEL INSTABILITY ALONG AND WITHIN THE POST-
FRONTAL AIR MASS, WHICH MAY LEAD TO SNOW SHOWERS AT TIMES BETWEEN
06Z-12Z. SNOW SHOWERS MAY BE CONVECTIVE IN NATURE AND ORGANIZE INTO
BANDS, WHICH MAY LEAD TO A BRIEF REDUCTION IN VISIBILITY AND
HAZARDOUS TRAVEL CONDITIONS. MOST OF THE SNOW SHOWER ACTIVITY WILL
BE LIGHT, HOWEVER. A COUPLE OF TENTHS TO A HALF OF AN INCH OF SNOW
IS POSSIBLE IN THE HEAVIER SNOW SHOWERS.
LONG TERM (FRIDAY THROUGH WEDNESDAY)
ISSUED AT 308 AM EST THU DEC 18 2025
ON FRIDAY, A QUICK SHOT OF COLD WEATHER WILL BE PUSHING ACROSS
CENTRAL INDIANA IN THE WAKE OF THE PASSAGE OF A COLD FRONT. THE CORE
OF THE COLD AIR WILL BE OVER INDIANA AS WE START THE DAY, AND WARM
AIR ADVECTION WILL BEGIN, BUT 850MB TEMPS ARE SUGGESTED TO ONLY RISE
TO NEAR -6C BY THE END OF THE DAY. HIGHS WILL STRUGGLE TO REACH THE
MIDDLE AND UPPER 20S AMID THE COLD AIR MASS. OTHERWISE, A STRONG
RIDGE OF HIGH PRESSURE WILL BE IN PLACE WITHIN THE LOWER LEVELS,
PASSING ACROSS INDIANA THROUGH THE DAY. FORECAST SOUNDINGS THROUGH
SATURDAY SHOW A DRY COLUMN, WITH SUBSIDENCE ON FRIDAY AND A SLOW
TREND TOWARD SATURATION ON SATURDAY THAT NEVER QUITE GETS THERE LATE
IN THE DAY. THUS DRY WEATHER WILL BE EXPECTED ON BOTH FRIDAY AND
SATURDAY.
ON SATURDAY NIGHT INTO SUNDAY, MODELS SUGGEST A QUICK MOVING SHORT
WAVE PASSING WITHIN THE FLOW ALOFT. BEST FORCING REMAINS WELL NORTH
OF INDIANA, OVER ONTARIO AND THE NORTHERN GREAT LAKES. THIS ARRIVES
NEAR 00Z, BUT SUBSIDENCE QUICKLY ARRIVES LATER IN THE EVENING AS THE
WAVE ALOFT AND WHAT IS EXPECTED TO BE A DRY COLD FRONT PASSES FAST.
ANOTHER STRONG HIGH PRESSURE SYSTEM IS THEN EXPECTED TO ARRIVE FOR
SUNDAY. THUS A DRY FORECAST LOOKS LIKE THE WAY TO GO HERE THROUGH
SUNDAY NIGHT, ALTHOUGH WE WILL KEEP AN EYE TO THE MOISTURE STARVED
FRONT AND WAVE PASSING TO THE NORTH FOR POSSIBLE CHANGES.
ON MONDAY THROUGH WEDNESDAY...WEAK RIDGING OVER THE CENTRAL CONUS
WILL STRENGTHEN THROUGH WEDNESDAY INTO A STRONGER RIDGE WITH A
RIDGE AXIS SETTLING JUST WEST OF THE MISSISSIPPI VALLEY. THIS WILL
PLACE CENTRAL INDIANA WITHIN NORTHWEST FLOW ALOFT. LITTLE IN THE WAY
OF FORCING DYNAMICS IS SUGGESTED TO PASS, WHILE HIGH PRESSURE PASSES
THROUGH THE AREA AT THE SURFACE. THIS WILL RESULT IN DRY AND MILD
WEATHER FOR MONDAY AND TUESDAY WITH ABOVE NORMAL TEMPERATURES.
BY WEDNESDAY WITHIN THE LOWER LEVELS A WARM FRONT IS SUGGESTED TO
SET UP NEAR THE OHIO RIVER AND SETTLE OVER CENTRAL INDIANA THROUGH
THE DAY. A STRONG BLOCKING HIGH PRESSURE SYSTEM WILL BE FOUND TO THE
SOUTH, PREVENTING MUCH IN THE WAY OF MOISTURE ARRIVING WHILE RIDGING
WILL BE IN PLACE ALOFT. THUS CONFIDENCE FOR ANY PRECIP AT THIS TIME
IS LOW ON WEDNESDAY, ALTHOUGH THE NBM MAY TRY TO INCLUDE SOME LOW
POPS.
AVIATION (12Z TAF ISSUANCE)
ISSUED AT 630 AM EST THU DEC 18 2025
IMPACTS:
- MVFR CEILINGS DEVELOPING AFTER 12Z, IFR CEILINGS DEVELOPING AFTER
15Z
- LOW-LEVEL WIND SHEAR INCREASING AFTER 12Z
- RAIN ARRIVES THIS MORNING, BECOMING MODERATE TO HEAVY DURING
AFTERNOON.
- GUSTY SURFACE WIND DEVELOPING TOWARDS 12Z, STRONGEST (40 KT) WITH
THE BAND OF CONVECTIVE RAIN SHOWERS FROM 18-21Z.
DISCUSSION:
A POTENT SYSTEM WILL BRING A VARIETY OF IMPACTS TO AVIATION THROUGH
THE PERIOD.
A LOW LEVEL JET WILL BRING NON-CONVECTIVE LLWS LATER THIS EVENING
AND WILL CONTINUE INTO THURSDAY MORNING. GUSTY SURFACE WINDS WILL
DEVELOP THURSDAY, WITH THE MOST INTENSE GUSTS DURING THE AFTERNOON
IN SHOWERS ALONG A COLD FRONT.
CLOUDS WILL GRADUALLY THICKEN AND LOWER, REACHING IFR AT TIMES ON
THURSDAY. THERE WILL BE SOME BRIEF IMPROVEMENT LATE IN THE PERIOD
WITH A DRY SLOT IN THE SYSTEM.
RAIN WILL BECOME WIDESPREAD THURSDAY. EMBEDDED THUNDER IS POSSIBLE,
BUT EXPECTED COVERAGE WILL BE TOO LOW TO MENTION. SNOW SHOWERS ARE
LIKELY BEHIND THE COLD FRONT AFTER 04Z, PERSISTING THROUGH ABOUT
12Z. LINGERING MVFR STRATUS IS LIKELY TO PERSIST INTO THE
AFTERNOON HOURS FRIDAY.
IND WATCHES/WARNINGS/ADVISORIES
NONE.
UPDATE...MELO
SHORT TERM...ECKHOFF
LONG TERM...PUMA
AVIATION...ECKHOFF
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