815
FXUS63 KIND 181746
AFDIND
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
1246 PM EST WED DEC 18 2024
KEY MESSAGES
- RAIN ENDING THIS MORNING, LEADING TO A CLOUDY AND COOLER
AFTERNOON
- COOLER THAN NORMAL TEMPERATURES WILL RETURN THURSDAY THROUGH THE
WEEKEND
- LIGHT SNOW POSSIBLE THURSDAY NIGHT INTO FRIDAY. THE SNOW COULD
IMPACT THE FRIDAY MORNING COMMUTE.
- RAIN FOR CHRISTMAS EVE INTO CHRISTMAS DAY
FORECAST UPDATE
ISSUED AT 951 AM EST WED DEC 18 2024
GLOOMY MORNING IN PROGRESS AS THICK CLOUD COVER REMAINS ACROSS THE
REGION. THE LAST OF THE STEADIER RAINFALL WAS MOVING OUT OF FAR
EASTERN PORTIONS OF THE FORECAST AREA WITH A BROKEN...NARROW BAND OF
SPRINKLES PIVOTING EAST THROUGH THE AREA IN ADVANCE OF AN UPPER
LEVEL WAVE. 14Z TEMPS RANGED FROM THE MID 30S TO LOWER 40S.
DEEPER MOISTURE WILL CONTINUE ITS DEPARTURE EAST OVER THE NEXT
SEVERAL HOURS WITH ANY LINGERING DRIZZLE OR SPRINKLES DIMINISHING.
TO THIS POINT...THERE HAS NOT BEEN ANY FLURRIES NOTED ACROSS FAR
NORTHERN SECTIONS OF CENTRAL INDIANA AND OUTSIDE OF A SMALL AND
LOCALIZED OCCURRENCE THROUGH MIDDAY AM NOT EXPECTING ANY FLURRIES
GOING FORWARD.
COLD ADVECTION WILL SETTLE OVER THE REGION FOR THE AFTERNOON WITH
SHALLOW MOISTURE BECOMING TRAPPED BENEATH AN INVERSION AS DRIER AIR
ALOFT ADVECTS OVER THE OHIO VALLEY. WHILE A NARROW CLEARING AXIS IS
SET TO PIVOT ACROSS THE WABASH VALLEY OVER THE NEXT FEW HOURS...
EXPECT LOWER CLOUDS WILL LARGELY PERSIST ACROSS MUCH OF THE FORECAST
AREA THROUGH LATE DAY.
TEMPS ARE NOT LIKELY TO MOVE MUCH THROUGH THE AFTERNOON WITH HIGH
RANGING FROM THE UPPER 30S TO MID 40S FROM NORTH TO SOUTH. ZONE AND
GRID UPDATES OUT.
SHORT TERM (TODAY AND TONIGHT)
ISSUED AT 245 AM EST WED DEC 18 2024
LOW LEVEL MOISTURE WILL CONTINUE TO INCREASE OVER THE NEXT FEW
HOURS, AS LOW LEVEL WSW FLOW STRENGTHENS. THIS HAS LEAD TO A
WIDESPREAD 5-7KFT STRATUS DECK ACROSS MOST OF CENTRAL INDIANA.
WITHIN THIS CLOUD DECK, PRECIPITATION PROCESSES HAVE BEGUN, LEADING
TO FURTHER LOW LEVEL SATURATION, AND EVENTUALLY RAIN. THIS PROCESS
WILL WORK EASTWARD THROUGHOUT THE NIGHT AND INTO THE MORNING, WITH
NUMEROUS SHOWERS ACROSS THE THE I-70 CORRIDOR AND SOUTHWARD AFTER
09Z. A MAJORITY OF THE QPF WILL BE SOUTH OF THE I-70 CORRIDOR (0.2-
0.4"), WITH 0.05-0.1" EXPECTED NORTH OF I-70. A STATIONARY BOUNDARY
IS CURRENTLY LOCATED ALONG THE OHIO RIVER, OF WHICH IS EXPECTED TO
LEAD TO GREATER LOW LEVEL VERTICAL MOTION AND HIGHER PRECIPITATION
RATES FOR FAR SOUTHERN IN. THE CURRENT EXPECTATION IS FOR THESE
HIGHER RATES TO REMAIN SOUTH OF KNOX/DAVIESS/MARTIN COUNTIES, BUT
WITH THE MARGIN OF ERROR ONLY BEING IN THE TENS OF MILES, THIS IS
SOMETHING THAT WILL NEED TO BE MONITORED THIS MORNING.
THE LIFT IN THIS INITIAL PRECIPITATION WILL BE MOSTLY DUE TO A
STRONG AREA OF 900-750MB 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 EARLY THIS MORNING. WITH THAT SAID, THERE WILL BE A PUSH OF
COLDER 850-700MB TEMPERATURES ALONG THE MID LEVEL TROUGH POST 12Z
THIS MORNING. IF PRECIPITATION DOES OCCUR WITHIN THIS COOLER
CORRIDOR, SNOW WILL LIKELY MIX WITH RAIN. HREF MEMBERS CURRENTLY ARE
VARIED IN COVERAGE OF PRECIPITATION WITH THIS MID LEVEL WAVE
LEADING TO LOW CONFIDENCE IN OCCURRENCE. EITHER WAY, SNOW
ACCUMULATIONS WOULD BE CONFINED TO GENERALLY CRAWFORDSVILLE TO
MUNCIE AND AREAS NORTH, AND WOULD BE LESS THAT 0.2", WITH NO IMPACT
EXPECTED ON WARM ROADWAYS.
THE REST OF THE DAY WILL BE RATHER QUIET, WITH HIGH PRESSURE
BUILDING UNDERNEATH MODEST CAA. THIS WILL LEAD TO MUCH COOLER
TEMPERATURES TODAY WITH AFTERNOON HIGHS IN THE UPPER 30S TO LOW 40S.
GUIDANCE IS SUGGESTING SOME CLEARING IN CLOUD COVER THIS AFTERNOON,
BUT GIVEN HOW QUICKLY HIGH PRESSURE BUILDS IN, THERE IS LIKELY TO BE
A REMNANT SUPPRESSED SATURATED LAYER THOUGH MOST OF THE DAY AND
TONIGHT. THIS SHOULD ALSO BUOY OVERNIGHT TEMPERATURES A LITTLE,
KEEPING LOWS IN THE UPPER 20S TO LOW 30S. IF BREAKS/COOLER OVERNIGHT
LOWS DUE OCCUR, THEY WOULD BE MOST LIKELY OVER W/SW PORTIONS OF
CENTRAL IN.
LONG TERM (THURSDAY THROUGH TUESDAY)
ISSUED AT 245 AM EST WED DEC 18 2024
FOCUS IN THE LONG TERM IS ON A COUPLE OF PRECIPITATION EVENTS. ONE
IS A CLIPPER SYSTEM AROUND FRIDAY AND THE OTHER IS RAIN FOR
CHRISTMAS EVE/CHRISTMAS DAY.
THURSDAY WILL BE QUIET AHEAD OF AN APPROACHING UPPER TROUGH AND
SURFACE LOW. THURSDAY NIGHT INTO FRIDAY, THE UPPER TROUGH WILL MOVE
IN, AND AN AREA OF LOW PRESSURE WILL MOVE THROUGH NORTHERN INDIANA.
GOOD ISENTROPIC LIFT WILL ACCOMPANY THE SYSTEM, AND AN UPPER JET
WILL PROVIDE ADDITIONAL FORCING. BEST MOISTURE THOUGH WILL BE
CONFINED TO NEAR AND NORTH OF THE SURFACE LOW.
SOME MODEL FORECAST SOUNDINGS DO SHOW LIMITED MOISTURE IN THE ICE
FORMATION ZONE, SO THERE IS SOME CONCERN FOR SOME FREEZING DRIZZLE
WITH PRECIPITATION ONSET THURSDAY NIGHT. HOWEVER, GIVEN THE
UNCERTAINTY, WILL LEAVE MENTION OF THAT OUT FOR NOW.
WILL GO WITH LIKELY POPS ACROSS NORTH AND NORTHEAST PORTIONS OF THE
AREA THURSDAY NIGHT INTO FRIDAY MORNING, WITH SNOW AS THE
PRECIPITATION TYPE. AS COLD ADVECTION CONTINUES BEHIND THE SYSTEM
FRIDAY AFTERNOON, ADDITIONAL SCATTERED SNOW SHOWERS WILL BE AROUND.
WILL KEEP CHANCE POPS GOING THEN.
SNOWFALL AMOUNTS HAVE COME UP WITH THE SOUTHWARD TREND OF THE LOW,
BUT AMOUNTS WILL STILL BE RELATIVELY LIGHT. HIGHEST AMOUNTS NEAR AN
INCH WOULD BE ACROSS THE NORTHEAST FORECAST AREA WITH LIGHTER
AMOUNTS TO THE SOUTHWEST. THE FRIDAY MORNING COMMUTE COULD BE
AFFECTED BY THIS LIGHT SNOWFALL.
SATURDAY THROUGH MUCH OF THE DAY MONDAY LOOK TO BE QUIET AND
COLD WITH SURFACE HIGH PRESSURE IN CONTROL.
FOR CHRISTMAS EVE INTO CHRISTMAS DAY, AN UPPER TROUGH WILL MOVE INTO
THE AREA. AT THE SURFACE, AN INITIAL FRONT WILL STALL NEARBY, AND A
SURFACE WAVE WILL RIDE ALONG IT. PLENTIFUL MOISTURE WILL BE BROUGHT
INTO THE SYSTEM FROM THE SOUTH AND SOUTHWEST. TEMPERATURES WILL BE
WARM ENOUGH FOR ALL RAIN.
QUESTIONS REMAIN THOUGH ON TIMING OF FORCING, WHERE THE FRONT WILL
HANG UP, AND THE SURFACE LOW TRACKS. THESE WILL HAVE IMPACTS ON WHEN
THE HIGHEST POPS WILL OCCUR AND WHERE THE HEAVIEST RAIN WILL FALL.
00Z GFS HAS 48 HOUR RAINFALL AMOUNTS OVER 2 INCHES IN THE SOUTH, BUT
THE GEFS AND OTHER MODELS PLACE THIS AXIS SOUTH OF THE AREA. THIS
WILL BE SOMETHING TO KEEP AN EYE ON.
HIGH TEMPERATURES WILL WARM INTO THE MID 40S BY CHRISTMAS DAY.
AVIATION (18Z TAF ISSUANCE)
ISSUED AT 1243 PM EST WED DEC 18 2024
IMPACTS:
- VFR CEILINGS BECOMING MVFR THIS EVENING
- IFR TO MVFR CIGS OVERNIGHT WITH PATCHY FOG DEVELOPING
DISCUSSION:
LATEST SATELLITE IMAGERY SHOWS VFR CIGS FOR THE SOUTHEASTERN HALF OF
INDIANA WITH AN AREA OF LOW MVFR TO IFR STRATUS PUSHING IN FROM THE
NORTHWEST. KLAF HAS ALREADY REPORTED CIGS AROUND OVC009 WITH
UPSTREAM OBSERVATIONS INDICATING THESE LOW CEILINGS WILL LIKELY
PERSIST THROUGH THE REST OF THE AFTERNOON AND CONTINUE PUSHING SOUTH
AND EAST. HAVE CEILINGS LOWERING AT ALL TAF SITES TO LOW MVFR LEVELS
OVER THE NEXT FEW HOURS. CIGS WILL LIKELY BECOME BKN OVERNIGHT AS
DRIER AIR MOVES IN ALOFT; HOWEVER LEFTOVER MOISTURE TRAPPED AT THE
SURFACE UNDER A DEVELOPING INVERSION MAY KEEP A LOW BKN DECK AROUND
FOR MUCH OF THE OVERNIGHT HOURS.
ALSO CONCERNED WITH THE POSSIBILITY OF FOG DEVELOPMENT OVERNIGHT AS
HIGH PRESSURE BRIEFLY BECOMES CENTERED OVER THE REGION. ADDED PATCHY
FOG TO ALL TAF SITES WITHIN THE 08-15Z TIMEFRAME TONIGHT INTO
TOMORROW MORNING. THINKING LOWEST CIGS AND VIS WILL LIKELY BE IN THE
WABASH RIVER VALLEY AND AROUND KBMG. THERE MAY BE AREAS ACROSS THE
STATE THAT SEE LOW STRATUS WITH NO VIS RESTRICTIONS, WHILE OTHERS
SEE PATCHY FOG WITH LOWER VIS. CONFIDENCE IS LOWER PINPOINTING WHICH
AREAS SEE WHICH, SO THAT WILL BE SOMETHING TO WATCH CLOSELY TONIGHT.
CEILINGS MAY HAVE TROUBLE RECOVERING TOMORROW AS SOME SHORT-TERM
GUIDANCE SHOWS MOISTURE REMAINING TRAPPED NEAR THE SURFACE MUCH OF
THE DAY. THINKING CIGS WILL AT LEAST RISE TO MVFR LEVELS BY THE END
OF THE TAF PERIOD THOUGH.
OTHER THAN THAT, NW WINDS IN THE 09-13 KT RANGE THIS AFTERNOON WILL
BECOME NEARLY CALM DURING THE OVERNIGHT HOURS, THEN BECOME
SOUTHEASTERLY BY LATE MORNING.
IND WATCHES/WARNINGS/ADVISORIES
NONE.
UPDATE...RYAN
SHORT TERM...UPDIKE
LONG TERM...50
AVIATION...CM
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