Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 251114
AFDIND

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
614 AM EST SUN JAN 25 2015

.UPDATE...
THE NEAR TERM SECTION HAS BEEN UPDATED BELOW.

&&

.SYNOPSIS...
ISSUED AT 357 AM EST SUN JAN 25 2015

AN ALBERTA CLIPPER WILL MOVE QUICKLY THROUGH THE OHIO VALLEY TODAY
AND TONIGHT...BRINGING A WINTRY MIXTURE OF RAIN AND SNOW. SOME LIGHT
ACCUMULATIONS ARE POSSIBLE AS PRECIPITATION CHANGES TO ALL SNOW LATE
TODAY INTO TONIGHT WITH COLDER AIR WRAPPING IN. PRECIPITATION
CHANCES WILL COME MONDAY NIGHT...WEDNESDAY NIGHT/THURSDAY AND AGAIN
OVER THE WEEKEND AS UPPER LEVEL WAVES TRACK THROUGH THE AREA. AFTER
A COLD START ON MONDAY...TEMPERATURES WILL WARM TO SEASONABLE LEVELS
FOR THE SECOND HALF OF THE WEEK.

&&

.NEAR TERM /TODAY AND TONIGHT/...
ISSUED AT 614 AM EST SUN JAN 25 2015

CLOUDS STEADILY EXPANDING ACROSS THE FORECAST AREA EARLY THIS
MORNING AS LOW PRESSURE MOVES ACROSS IOWA AND NORTHERN MISSOURI.
LOWS HAVE BEEN REACHED ALREADY AS WARM ADVECTION AND CLOUDS ARE
SERVING TO KEEP TEMPS STEADY OR SLOWLY RISING. ENTIRE FORECAST AREA
AT OR WARMER THAN THE 32F MARK AT 08Z.

DOWN INTO NOWCAST MODE WITH THE APPROACHING ALBERTA CLIPPER POISED
TO ROTATE INTO THE OHIO VALLEY BY THIS EVENING. TEMPERATURE TRENDS
AT GROUND LEVEL AND IN THE NEAR SURFACE LAYER PROVING TO BE A
CRITICAL FACTOR IN DETERMINING POTENTIAL SNOW ACCUMULATIONS LATER
TODAY AND THIS EVENING AS HAS BEEN EXPECTED. SEEMS EVERY STORM SO
FAR THIS WINTER HAS HAD MARGINAL TEMP ISSUES THAT INITIALLY HAVE NOT
BEEN CAPTURED WELL BY THE MODEL SUITE...ONLY TO RECOVER SOMEWHAT
WITHIN 24 HOURS OF STORM IMPACT. NEEDLESS TO SAY...ITS FRUSTRATING
FOR METEOROLOGISTS. THIS EVENT APPEARS TO BE FOLLOWING THAT TREND AS
00Z GUIDANCE...AND ESPECIALLY THE HI-RES WRF/HRRR/RAP...WHICH HAVE
INGESTED WARMER TEMP OBSERVATIONS TO THE NORTHWEST AND ADJUSTED
ACCORDINGLY. THE RESULT WILL BE A LOWERING OF SNOWFALL TOTALS ACROSS
THE BOARD AS WARMER AIR IN THE LOW LEVELS WILL BE SLOWER TO DEPART
DURING THE AFTERNOON. MORE ON THE SPECIFICS SHORTLY.

TEMPS BACK ACROSS THE MID MISSISSIPPI VALLEY ARE WARMER THAN ALMOST
ALL MODEL GUIDANCE INDICATED ON SATURDAY...WITH 40S ALL THE WAY
NORTH INTO SOUTHERN IOWA. SURFACE TEMPS ACROSS THE FORECAST AREA ARE
ALREADY RUNNING A FEW DEGREES WARMER THAN PROGGED AS WELL...WITH
WARM ADVECTION AHEAD OF THE SYSTEM ENABLING TEMPS TO CONTINUE TO
RISE THROUGH MIDDAY. UTILIZED A BLEND OF WRF/RAP HOURLY TEMPS TO
POPULATE THE GRIDS AND PRODUCE HIGHS FOR TODAY WHICH NOW LOOK TO
RANGE FROM THE MID 30S FAR NORTH TO LOWER 40S SOUTH. ALL AVAILABLE
GUIDANCE IS NOW DELAYING THE PUSH OF COLDER AIR IN THE NEAR SURFACE
LAYER WITH SUBFREEZING TEMPS SWEEPING SOUTH BEGINNING AFTER 20-21Z
INTO THE EVENING HOURS.

PRECIP WILL OVERSPREAD CENTRAL INDIANA AFTER DAYBREAK...IMPACTING
THE NORTHERN HALF OF THE FORECAST AREA FIRST AND THE REMAINDER OF
THE REGION BY EARLY AFTERNOON. MAY SEE A BRIEF PERIOD OF RA/SN MIX
ACROSS FAR NORTHERN COUNTIES AT PRECIP ONSET AS THE BOUNDARY LAYER
MOISTENS BUT BASED ON MODEL SOUNDINGS AND SURFACE TEMP THOUGHTS
ABOVE...EXPECT PRECIP TO FALL AS RAIN ACROSS THE ENTIRE FORECAST
AREA FOR AT LEAST 3-5 HOURS THROUGH ABOUT 18Z. THE BOUNDARY LAYER
WILL OUTPACE THE GROUND/NEAR SURFACE LAYER IN COOLING THROUGH THE
REST OF THE AFTERNOON...WITH THE MAIN PRECIP TYPE GRADUALLY
TRANSITIONING TO SNOW AN HOUR OR TWO AHEAD OF TEMPS FALLING TO 32F
OR LOWER. BY 00Z...EXPECT SNOW NORTH OF A TERRE HAUTE TO SHELBYVILLE
LINE WITH RAIN BEGINNING TO MIX WITH SNOW FURTHER SOUTH. AS COLDER
AIR CONTINUES TO SWEEP INTO THE REGION BEHIND THE SURFACE
WAVE...PRECIP TYPE WILL CHANGE TO ALL SNOW ACROSS ALL OF THE
SOUTHERN COUNTIES BY LATE EVENING. PRECIP WILL THEN END FROM
NORTHWEST TO SOUTHEAST AFTER MIDNIGHT.

AS MENTIONED ABOVE...THE IMPACTS OF THE WARMER AIR IN THE NEAR
SURFACE LAYER REQUIRES TRIMMING SNOWFALL TOTALS ACROSS THE BOARD AS
IMPACTS WILL BE MITIGATED TO SOME DEGREE. POTENTIAL FOR MID LEVEL
DEFORMATION AND BANDING REMAINS DURING THE LATE AFTERNOON AND EARLY
EVENING ACROSS THE NORTHEAST FORECAST AREA...AND THIS REMAINS THE
LOCATION WHERE HIGHEST AMOUNTS OF SNOW AND GREATEST IMPACTS MAY BE
AS THESE FEATURES COULD SUPPORT A BRIEF PERIOD OF HIGHER INTENSITY
SNOWFALL RATES AND COMPENSATE FOR THE MARGINAL SURFACE TEMPS.
ELSEWHERE ACROSS THE FORECAST AREA HOWEVER...BEST FORCING ALOFT
COMES THROUGH PRIOR TO EARLY EVENING WITH BULK OF THE PRECIP FALLING
AS RAIN OR A MIX. ACCUMS ARE POSSIBLE INTO THE EVENING BUT SNOWFALL
SHOULD BE LIGHTER AS DEEPER FORCING WILL ALREADY BE MOVING AWAY TO
THE EAST WITH THE SURFACE WAVE.

HIGHEST SNOWFALL TOTALS NOW EXPECTED TO BE CONFINED FROM KOKOMO E/SE
THROUGH MUNCIE AND WINCHESTER WHERE 2 TO 3 INCHES WITH LOCALLY
HIGHER AMOUNTS REMAIN POSSIBLE BY LATE TONIGHT. EXPECT SNOWFALL
TOTALS TO DROP OFF QUICKLY TO THE SOUTHWEST OF THIS LINE...WITH THE
ONE INCH ACCUM LINE FOLLOWING INTERSTATE 74 FAIRLY CLOSELY. AMOUNTS
WILL DROP TO A FEW TENTHS AT BEST OVER THE SOUTHWEST HALF OF THE
FORECAST AREA. THIS REQUIRES SOME CHANGES TO THE ADVISORY...AND WILL
BE CUTTING IT BACK TO THE FAR NORTHEAST FORECAST AREA. ALSO PLAN ON
DELAYING THE START TIME TO 20-21Z. NORTHERLY WINDS WILL BECOME GUSTY
DURING THE EVENING BUT BLOWING/DRIFTING OF SNOW SHOULD BE LARGELY
MINIMIZED TO LOCALIZED AREAS. SLICK AND SNOW COVERED ROADS WILL
INCREASINGLY BECOME AN ISSUE DURING THE EVENING AND OVERNIGHT AS
TEMPS TUMBLE. IF TEMP FALLS ARE EVEN SLOWER...FURTHER CHANGES TO THE
ADVISORY MAY BE NEEDED.

TEMPS...AS MENTIONED...USED WRF/RAP AS A GUIDE FOR TEMPS INTO THE
EVENING. RESULTANT HIGH TEMPS WERE NEAR OR JUST UNDER MOS. MAVMOS
LOOKED REASONABLE FOR LOWS TONIGHT WITH TEMPS FALLING INTO THE TEENS
AND LOWER 20S IN MOST AREAS BY DAYBREAK MONDAY.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
ISSUED AT 357 AM EST SUN JAN 25 2015

FORECAST CHALLENGES FOCUS ON LIGHT SNOW CHANCES MONDAY NIGHT AS A
WEAK WAVE ALOFT TRAVERSES THROUGH THE REGION.

LIGHT SNOW WILL END PRIOR TO DAYBREAK MONDAY...WITH POTENTIAL FOR
SOME CLEARING AS MUCH DRIER AIR WRAPS INTO THE REGION FROM THE
NORTH. DRY BUT CHILLY WEATHER IS EXPECTED MONDAY AS A SURFACE RIDGE
TRACKS QUICKLY ACROSS THE OHIO VALLEY. ANOTHER PIECE OF ENERGY ALOFT
WILL DROP THROUGH THE GREAT LAKES MONDAY AFTERNOON AND EVENING AND
INTO THE BACK SIDE OF THE DEPARTING UPPER TROUGH OFF TO OUR EAST.
NICE AXIS OF FORCING ALOFT WITH THIS FEATURE CONTINUES TO SUPPORT
POTENTIAL FOR SCATTERED SNOW SHOWERS TO IMPACT CENTRAL INDIANA
MONDAY NIGHT...ESPECIALLY ACROSS THE EASTERN HALF OF THE FORECAST
AREA IN CLOSER PROXIMITY TO THE UPPER WAVE. SNOW RATIOS SHOULD BE AT
OR JUST ABOVE CLIMO IN THE 12-1 RANGE WITH POTENTIAL FOR A FEW
TENTHS OF AN INCH TO FALL. SYSTEM WILL DEPART OFF TO THE SOUTHEAST
PRIOR TO DAYBREAK TUESDAY.

REMAINDER OF THE SHORT TERM WILL SEE A RETURN TO QUIET WEATHER WITH
HIGH PRESSURE BUILDING ACROSS THE REGION BY TUESDAY NIGHT. LOW
CLOUDS AGAIN ARE LIKELY TO BE QUITE STUBBORN TO BREAK UP TUESDAY
WITH COLD ADVECTION AND CYCLONIC FLOW LINGERING. KEPT SKIES MOSTLY
CLOUDY WITH MORE SUBSTANTIAL CLEARING HOLDING OFF UNTIL LATE TUESDAY
AND TUESDAY NIGHT.

TEMPS...GENERALLY UNDERCUT MAVMOS ON HIGHS MONDAY/TUESDAY WITH COLD
ADVECTION ACROSS THE AREA. NORTHERN HALF OF THE FORECAST AREA
EXPECTED TO STAY BELOW FREEZING ON MONDAY. A MOS BLEND LOOKED
REASONABLE FOR LOWS MONDAY/TUESDAY NIGHTS.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
ISSUED AT 238 AM EST SUN JAN 25 2015

MODELS ARE CLOSE ENOUGH THAT THE SUPERBLEND INITIALIZATION WAS
ACCEPTED FOR MOST ITEMS.

WEDNESDAY WILL BE DRY...BUT AN AREA OF LOW PRESSURE WILL BRING A
COLD FRONT THROUGH THE AREA WEDNESDAY NIGHT INTO THURSDAY. THIS WILL
KEEP A CHANCE FOR PRECIPITATION DURING THAT PERIOD. LOOKS LIKE
TEMPERATURES WILL BE JUST COLD ENOUGH FOR MAINLY SNOW WEDNESDAY
NIGHT...THEN READINGS WILL WARM ENOUGH FOR RAIN ON THURSDAY.

COULD STILL BE SOME LINGERING CHANCES FOR LIGHT SNOW BEHIND THE
SYSTEM THURSDAY NIGHT AS COLDER AIR MOVES IN...SO ACCEPTED
SUPERBLEND/S SLIGHT CHANCE POPS.

MODELS DIFFER ON TIMING OF NEXT SYSTEM AND THE ARRIVAL OF MUCH
COLDER AIR. ECMWF IS FASTER...GFS SLOWER. WITH THE UNCERTAINTIES
THAT FAR OUT DECIDED TO SIMPLY GO WITH THE INITIALIZATION FOR NOW
AND KEEP LOW POPS ON SATURDAY.

TEMPERATURES WILL COOL TOWARD THE END OF THE LONG TERM...WITH THE
POTENTIAL FOR MUCH COLDER AIR MOVING IN FOR THE SECOND HALF OF THE

&&

.AVIATION /DISCUSSION FOR THE 251200Z TAF ISSUANCE/...
ISSUED AT 531 AM EST SUN JAN 25 2015

IFR OR LOWER CONDITIONS EXPECTED BY 17Z MOST AREAS WITH IFR OR WORSE
CONTINUING THROUGH AT LEAST 00Z. RAIN WILL GIVE WAY TO SNOW BY 00Z.

AS AN AREA OF LOW PRESSURE MOVES INTO THE AREA TODAY...CONDITIONS
WILL QUICKLY DETERIORATE TO IFR OR WORSE. RAIN WILL DEVELOP ACROSS
THE AREA THIS MORNING...MIXING WITH AND THEN CHANGING TO SNOW BY
LATE AFTERNOON. SNOW WILL END DURING THE EVENING.

IN ADDITION TO THE POOR FLYING CONDITIONS...WINDS WILL GUST TO OVER
20KT AFTER 21Z.

CONFIDENCE IS MEDIUM TO LOW ON TIMING OF PRECIPITATION TYPES DUE TO
UNCERTAINTIES IN LOW LEVEL TEMPERATURES.

&&

.IND WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO MIDNIGHT EST
TONIGHT FOR INZ031-038-040>042-049.

&&

$$

SYNOPSIS...RYAN
NEAR TERM...RYAN
SHORT TERM...RYAN
LONG TERM....50
AVIATION...50

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