650
FXUS63 KIND 150509
AFDIND
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
1209 AM EST SUN DEC 15 2024
KEY MESSAGES
- MILDER TEMPERATURES THROUGH EARLY NEXT WEEK, ESPECIALLY MONDAY
- WIDESPREAD RAIN TONIGHT INTO SUNDAY, CHANGING TO DRIZZLE AS THE
DAY GOES ON SUNDAY; ONE HALF TO ONE INCH LIKELY, WITH LOCALLY HIGHER
AMOUNTS POSSIBLE
- A SECOND ROUND OF RAIN WITH THE POTENTIAL FOR EMBEDDED
THUNDERSTORMS ARRIVES EARLY ON MONDAY. UNCERTAINTY IS HIGH ON
SPECIFIC LOCATIONS, BUT LOCALLY HEAVY RAINFALL AMOUNTS BETWEEN 1
AND 3 INCHES ARE POSSIBLE
- COOLER TEMPERATURES ARRIVE FROM TUESDAY ONWARD
FORECAST UPDATE
ISSUED AT 1000 PM EST SAT DEC 14 2024
A LONG-AWAITED AND MUCH-NEEDED BAND OF LIGHT TO MODERATE RAIN IS
CURRENTLY STRETCHED NNW TO SSE ACROSS THE MIDDLE TWO-THIRDS OF THE
IND CWA...WITH LESS-ORGANIZED, YET NUMEROUS RW-'S ALONG ITS EDGES,
BOTH SOUTH OF TERRE HAUTE AND NORTH OF NEW CASTLE. PRECIPITATION
WILL CONTINUE TO STEADILY ADVANCE IN A NORTH-NORTHEASTERLY DIRECTION
THROUGH THE MIDDLE OF THE NIGHT...WHICH WILL BE REPLACED (FROM
SW TO NE) BY MORE SCATTERED SHOWERS CONNECTED BY AREAS OF DRIZZLE.
EXPECT TOTAL RAINFALL BY DAWN AROUND THE 0.40 TO 0.80 INCH RANGE,
WITH SOME LOCAL TOTALS POSSIBLY CLOSER TO 1.00 INCH.
MODERATE BREEZES WILL CONTINUE TO SLOWLY VEER THROUGH SOUTHEASTERLY
COMPONENTS TOWARDS THE SUPPORTING WAVE PASSING JUST TO OUR NORTH...
WITH A FEW GUSTS REACHING 20-25 MPH IN EMBEDDED STRONGER SHOWERS.
TEMPERATURES CURRENTLY AROUND 40F TO 45F WILL HOLD STEADY OR SLOWLY
INCREASE AMID THE WARM ADVECTIVE FLOW THROUGH DAWN.
SHORT TERM (THIS EVENING THROUGH SUNDAY)
ISSUED AT 304 PM EST SAT DEC 14 2024
A DAMP AND DREARY FINISH TO THE WEEKEND IS EXPECTED ACROSS CENTRAL
INDIANA.
A VERTICALLY STACKED LOW PRESSURE SYSTEM WILL STEADILY MAKE ITS WAY
FROM THE MID-MISSOURI VALLEY INTO THE LOWER GREAT LAKES/UPPER OHIO
VALLEY TONIGHT INTO SUNDAY. NATIONAL RADAR MOSAIC SHOWS A BROAD AREA
OF RAIN AHEAD OF THIS LOW ASSOCIATED WITH THE MAIN WARM CONVEYOR
BELT AND SOLID LOW LEVEL JET, WHICH WILL PASS ACROSS THE AREA
STARTING LATE THIS AFTERNOON THROUGH TONIGHT INTO EARLY SUNDAY.
FAIRLY DEEP SATURATION AND GOOD FORCING FOR ASCENT IS EXPECTED
THROUGHOUT MUCH OF THE NIGHT, AND THUS STEADY LIGHT TO MODERATE
RAINFALL CAN BE EXPECTED.
DESPITE A GRADUAL WEAKENING OF THE SURFACE LOW, A FAIRLY TIGHT
SURFACE PRESSURE GRADIENT WILL PROMOTE INCREASING BREEZES TONIGHT,
WITH OCCASIONAL GUSTINESS TO AROUND 20-25 MPH AT TIMES.
EVEN AS DEEPER SATURATION IS LOST BEGINNING LATE TONIGHT INTO SUNDAY
MORNING, WARM ADVECTION AND STEEP LOW LEVEL LAPSE RATES WILL
CONTINUE TO ALLOW FOR SHOWERS TO CONTINUE AT TIMES DURING THE
MORNING HOURS, BEFORE A LIKELY CHANGEOVER TO DRIZZLE IN THE
AFTERNOON AS PLENTIFUL LOW LEVEL MOISTURE SHALLOWS BUT LAPSE RATES
BELOW A FAIRLY STOUT INVERSION REMAIN STEEP.
EXPECT OVERCAST SKIES THROUGHOUT TONIGHT INTO SUNDAY AS A RESULT OF
THIS AMPLE MOISTURE AND THE AFOREMENTIONED INVERSION WHICH DEVELOPS
ON SUNDAY.
TOTAL RAINFALL AMOUNTS ARE LIKELY TO RANGE FROM ONE HALF TO ONE INCH
ACROSS THE AREA, WITH LOCALLY HIGHER AMOUNTS POSSIBLE. THIS IS
SUPPORTED WELL BY HREF LOCALIZED PROBABILITY MATCHED MEANS AND
DETERMINISTIC GUIDANCE WHICH HAS RAMPED UP A BIT IN RECENT RUNS.
PRECIPITATION AND CLOUD COVER, DESPITE MODEST LOW-MID LEVEL WARM
ADVECTION, WILL LIMIT DIURNAL RANGES. LOWS OVERNIGHT WILL LIKELY
RANGE FROM THE UPPER 30S TO NEAR 40 NORTH, TO THE MID 40S SOUTH -
THIS IS WELL SUPPORTED BY MODEL SURFACE WETBULB TEMPERATURES, WHICH
SHOULD BE A GOOD APPROXIMATION GIVEN PRECIPITATION IS EXPECTED MUCH
OF THE NIGHT. HIGHS ON SUNDAY GIVEN THE WARM ADVECTION WILL LIKELY
MANAGE TO RISE ABOUT 8-10 DEGREES, TOPPING OUT IN THE MID 40S TO MID
50S ACROSS THE AREA.
LONG TERM (SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 304 PM EST SAT DEC 14 2024
WITH NO AIR MASS CHANGE ANTICIPATED AFTER TONIGHT'S SYSTEM DEPARTS,
WE EXPECT ABUNDANT MOISTURE TO REMAIN WITHIN THE BOUNDARY LAYER
THROUGH SUNDAY INTO SUNDAY NIGHT. A BRIEF PERIOD OF RIDGING AND
SUBSIDENCE IS SHOWN BY GUIDANCE TO PASS THROUGH INDIANA BEFORE
ANOTHER SYSTEM ARRIVES ON MONDAY. ADDITIONALLY, MODEL SOUNDINGS SHOW
A SMALL POSITIVE AREA (CAPE) WITHIN THE BOUNDARY LAYER THROUGH
SUNDAY NIGHT. THIS, COMBINED WITH MODEST WARM AIR ADVECTION, SHOULD
LEAD TO BROAD LIFT BENEATH A SHARP INVERSION JUST ABOVE THE PBL.
GIVEN THE MOIST PROFILE, SUBSIDENT ATMOSPHERE ALOFT, AND BROAD PBL
LIFT... PATCHY FOG OR DRIZZLE IS LIKELY AT THE BEGINNING OF THE LONG
RANGE.
BY MONDAY, THE NEXT SYSTEM ARRIVES WITH ANOTHER ROUND OF RAINFALL.
THERE HAS BEEN SOME CHANGES WITHING GUIDANCE OVER THE PAST 24 HOURS,
HOWEVER, SO SOME DETAILS HAVE CHANGED. THE MOST APPARENT DEVIATION
WITHIN THE MODELS INVOLVES THE PARENT MID/UPPER LEVEL TROUGH. LATEST
GUIDANCE IS A BIT FLATTER AND FURTHER NORTH. THIS, IN TURN, LEADS TO
A MORE SUBDUED WARM CONVEYOR WHICH SHIFTS THE HEAVIER PRECIPITATION
AXIS FURTHER SOUTH. RAIN STILL APPEARS LIKELY ACROSS MUCH OF THE
CWA...BUT WE ARE A LITTLE LESS CONFIDENT ON 2 PLUS INCH AMOUNTS
NORTH OF BLOOMINGTON. GUIDANCE STILL SHOWS WEAK INSTABILITY MONDAY
AFTERNOON, AND WE MAINTAINED THE MENTION OF THUNDER SOUTH OF I-70.
A COOLING TREND BEGINS AFTER THE MONDAY'S SYSTEM DEPARTS AND ITS
ATTENDANT COLD FRONT SWINGS THROUGH. WHILE WE DO EXPERIENCE AN AIR
MASS CHANGE, DEEP ARCTIC AIR LIKE WE'VE SEEN EARLIER IN THE MONTH IS
NOT EXPECTED THIS TIME AROUND. INSTEAD, TEMPERATURES AT 850MB DROP
TO ONLY AROUND 0 TO 3C OR SO. COLDER, BUT NOT OVERLY SO. STILL,
THERE MAY BE JUST ENOUGH COLD AIR PRESENT TO CREATE PRECIPITATION
TYPE ISSUES FOR THE NEXT SYSTEM SLATED TO ARRIVE AROUND MID NEXT
WEEK. RIGHT NOW, THERE IS LITTLE IN THE WAY OF MODEL CONSISTENCY
REGARDING THIS SYSTEM. THOUGH MOST GUIDANCE DEPICTS THIS SYSTEM IN
ONE FORM OR ANOTHER WITH A VARIETY OF POSSIBLE OUTCOMES. UNTIL A
TREND BECOMES CLEAR/DOMINANT...WE WILL CARRY CHANCE POPS WITH RAIN
BECOMING A RAIN/SNOW MIX.
DAY 8-14: A SIGNAL FOR BROAD EAST COAST TROUGHING REMAINS WITHIN
ENSEMBLE GUIDANCE DURING THE SECOND HALF OF DECEMBER. SUCH A PATTERN
TYPICALLY LEADS TO A COOLER AND DRIER PATTERN IN INDIANA UNDER
NORTHWESTERLY FLOW. GUIDANCE DAMPENS THE TROUGHING SIGNATURE BY
ABOUT CHRISTMAS WHICH IS LIKELY DUE TO UNCERTAINTY BETWEEN THE
VARIOUS MEMBERS.
AVIATION (06Z TAF ISSUANCE)
ISSUED AT 1209 AM EST SUN DEC 15 2024
IMPACTS:
- CONDITIONS WILL DETERIORATE TO IFR OVERNIGHT
- IFR AND POTENTIALLY WORSE CONTINUING THROUGH AT LEAST MIDDAY
- WINDS TONIGHT OCCASIONALLY GUSTING TO 18-22KT INTO THE MORNING
DISCUSSION:
ALTHOUGH CEILINGS HAVE BEEN SLOW TO LOWER, STILL EXPECT THEM TO
REACH IFR CATEGORY OVERNIGHT FROM WEST TO EAST. THESE CONDITIONS
WILL PERSIST AT LEAST THROUGH MIDDAY, AND SOME LOWER CEILINGS ARE
POSSIBLE. MVFR CEILINGS MAY RETURN BY 21Z.
RAIN WILL CONTINUE AT TIMES THROUGH MID-MORNING OR SO BEFORE
TRANSITIONING TO DRIZZLE. VISIBILITY WILL DIP INTO MVFR AT TIMES.
IND WATCHES/WARNINGS/ADVISORIES
NONE.
UPDATE...AGM
SHORT TERM...NIELD
LONG TERM...ECKHOFF
AVIATION...50
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