Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 241035
AFDIND

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
535 AM EST SAT JAN 24 2015

.UPDATE...
THE AVIATION SECTION HAS BEEN UPDATED BELOW.

&&

.SYNOPSIS...
ISSUED AT 353 AM EST SAT JAN 24 2015

AFTER A DRY DAY TODAY...LOW PRESSURE WILL TRACK QUICKLY ACROSS THE
REGION SUNDAY. THIS FEATURE WILL BRING A MIXTURE OF RAIN AND SNOW
INITIALLY...WITH PRECIPITATION CHANGING TO ALL SNOW SUNDAY AFTERNOON
AND EVENING. SNOW ACCUMULATIONS ARE EXPECTED...ESPECIALLY ACROSS THE
NORTHERN HALF OF CENTRAL INDIANA. COLD AND DRY WEATHER WILL START
OUT THE NEW WEEK...WITH TEMPERATURES RETURNING TO NEAR SEASONABLE
LEVELS BY WEDNESDAY. THE PASSAGE OF A COLD FRONT ON THURSDAY WILL
BRING A RETURN TO COLDER WEATHER BY THE END OF THE WEEK.

&&

.NEAR TERM /TODAY/...
ISSUED AT 353 AM EST SAT JAN 24 2015

LOW CLOUDS SLOWLY CLEARING FROM THE WEST EARLY THIS MORNING AS LOW
PRESSURE TRACKS INTO THE MID ATLANTIC REGION. WHERE SKIES HAVE
CLEARED...08Z TEMPS HAD FALLEN INTO THE LOWER AND MIDDLE 20S.

QUIET DAY EXPECTED WITH THE MAIN FOCUS ON CLOUDS RETURNING AS
ANOTHER UPPER LEVEL WAVE TRACKS INTO THE REGION IN THE NORTHWEST
FLOW. SUNNY START WITH SURFACE RIDGING THIS MORNING. THIS WILL SHIFT
EAST BY MIDDAY WITH LOWER CLOUDS OVER THE WESTERN GREAT LAKES POISED
TO GRADUALLY OVERSPREAD MUCH OF THE REGION DURING THE AFTERNOON AS
THE UPPER WAVE TRACKS THROUGH THE AREA.

TEMPS...MOS HAS BEEN TOO WARM IN GENERAL RECENTLY AND CONSIDERING
THE CLOUD EXPANSION LATER TODAY WITH NO SUBSTANTIAL WARM
ADVECTION...WOULD PREFER TO UNDERCUT GUIDANCE FOR HIGHS AGAIN TODAY.
EXPECT HIGHS RANGING FROM THE UPPER 30S NORTH TO LOWER/MID 40S
SOUTH.

&&

.SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/...
ISSUED AT 353 AM EST SAT JAN 24 2015

PRIMARY FOCUS FOR THE SHORT TERM REMAINS ON THE POTENTIAL FOR SNOW
ACCUMS AS A QUICK MOVING BUT POTENT CLIPPER SYSTEM SWEEPS THROUGH
THE REGION SUNDAY AND SUNDAY NIGHT.

MODEL CONSENSUS HAS CONTINUED TO SHIFT THE SURFACE LOW TRACK FURTHER
SOUTH/WEST OVER THE LAST 24 HOURS...SOMETHING THAT WAS EXPECTED WITH
THE AMPLIFIED RIDGE ALOFT PRESENT ALONG THE PACIFIC COAST. THE
CONSENSUS TRACK TAKES THE SURFACE WAVE FROM CENTRAL IOWA TONIGHT
INTO CENTRAL KENTUCKY SUNDAY NIGHT...BEFORE PIVOTING EAST OFF THE
CAROLINA COAST BY MONDAY AFTERNOON. 00Z NAM CONTINUES TO PLAY
CATCHUP AND REMAINS FURTHEST NORTH WITH A TRACK ACROSS CENTRAL
INDIANA...BUT EVEN THIS IS A GOOD 150-200 MILES SOUTHWEST OF ITS
FORECAST TRACK FROM 24 HOURS AGO. NEXT TWO SETS OF PRIMARY MODEL
RUNS THROUGH TONIGHT WILL HELP DETERMINE IF THIS SHIFT IS LARGELY
FINISHED OR IF THE TRACK NUDGES EVEN FURTHER SOUTH...BUT DO EXPECT
ANY ADDITIONAL ADJUSTMENTS TO BE MORE SUBTLE THAN WHAT WE HAVE SEEN
OVER THE LAST 24-36 HOURS. MODEL CONSENSUS IN GENERAL HAS COME IN A
BIT WETTER WITH THIS SYSTEM AS WELL. COMBINED WITH THE SOUTHWARD
SHIFT TO THE SURFACE LOW TRACK...THE POTENTIAL FOR SNOW ACCUMS HAVE
INCREASED ACROSS CENTRAL INDIANA.

LIGHT PRECIP IS EXPECTED TO MOVE INTO THE NORTHERN AND WESTERN
PORTIONS OF THE FORECAST AREA PRIOR TO DAYBREAK SUNDAY...QUICKLY
OVERSPREADING CENTRAL INDIANA BY MIDDAY AS THE SURFACE WAVE RAPIDLY
APPROACHES. MODEL SOUNDINGS SUGGEST THE POSSIBILITY OF A RAIN/SNOW
MIX INITIALLY AS TEMPS AT GROUND LEVEL THROUGH THE NEAR SURFACE
LAYER WILL BE RIGHT AROUND FREEZING. PRESENCE OF A BRIEF PERIOD OF
WARM ADVECTION DURING THE MORNING AHEAD OF THE SURFACE WAVE WILL
LIKELY PROMPT MOST OF THE PRECIP TO FALL IN THE FORM OF RAIN UP
THROUGH THE I-70 CORRIDOR WITH A RAIN/SNOW MIX MAINTAINING FURTHER
NORTH.

LOW LEVEL THERMALS AND BOUNDARY LAYER TEMPS BEGIN TO CRASH HOWEVER
BY LATE MORNING...STEADILY FALLING DURING THE AFTERNOON AS THE LOW
TRACKS INTO CENTRAL KENTUCKY BY LATE DAY. THIS WILL PROMOTE A FASTER
TRANSITION TO ALL SNOW FROM NORTH TO SOUTH THROUGH THE AFTERNOON...
WITH THE EXPECTATION THAT MOST ALL LOCATIONS NORTH OF A
CRAWFORDSVILLE-NORTHERN INDY SUBURBS-NEW CASTLE LINE SEE SNOW AS THE
MAIN PRECIP TYPE AFTER 18Z. THE TRANSITION TO SNOW WILL ENCOMPASS
THE REST OF THE FORECAST AREA THROUGH THE LATE AFTERNOON AND EARLY
EVENING. SNOW WILL CONTINUE SUNDAY NIGHT...GRADUALLY ENDING FROM
NORTHWEST TO SOUTHEAST AFTER MIDNIGHT AS THE LOW TRACKS EAST INTO
THE CENTRAL APPALACHIANS.

SEVERAL CHALLENGES TO CONTEND WITH FOR THIS SYSTEM...WITH A SHARP
SOUTHERN DELINEATION EXPECTED BETWEEN HIGHER SNOW ACCUMS AND LITTLE
TO NO ACCUM. SO MANY FACTORS WILL ULTIMATELY DETERMINE WHERE THIS
AXIS SETS UP...INCLUDING HOW QUICKLY THE NEAR SURFACE LAYER AND
GROUND TEMPS COOL SUNDAY AFTERNOON ALONG WITH SNOWFALL RATES AND
RATIOS...AND THE SPECIFIC SURFACE LOW TRACK. CONFIDENCE CONTINUES TO
GROW ON HIGHEST SNOW ACCUMS ACROSS THE NORTHEAST QUADRANT OF THE
FORECAST AREA... FROM CARROLL COUNTY SOUTHEAST THROUGH KOKOMO...
ANDERSON...MUNCIE AND WINCHESTER. DEFORMATION AXIS SETS UP IN THIS
AREA COMBINED WITH ISENTROPIC LIFT WHICH LINGERS THROUGH THE EVENING
EVEN AS THE SURFACE WAVE PASSES TO THE SOUTH. THIS ENHANCED FORCING
SHOULD HELP SNOWFALL ACCUMS SUNDAY AFTERNOON BY INCREASING RATES
WITH MARGINAL TEMPS IN THE LOWER 30S. RATES WILL DECLINE SUNDAY
EVENING BUT TEMPS WILL PLUMMET AND RATIOS WILL RISE...ENABLING
CONTINUED ACCUMULATION THROUGH THE EVENING. IN ADDITION...THE PIVOT
POINT TO THE SURFACE LOW WOULD PLACE BEST CHANCE AT AN EXTENDED
PERIOD OF STEADIER SNOWFALL FROM NORTH CENTRAL/EAST CENTRAL INDIANA
EAST INTO OHIO.

THINK THE POTENTIAL EXISTS FOR 3-4 INCHES WITH LOCALLY HIGHER
AMOUNTS IN THE AREA OUTLINED ABOVE. SNOWFALL AMOUNTS WILL DROP OFF
QUICKLY FURTHER SOUTH TO AN INCH OR LESS SOUTH OF A ROCKVILLE-
FRANKLIN-SHELBYVILLE LINE. THIS WILL ONCE AGAIN PLACE A GRADIENT
ACROSS THE INDY METRO AND AS IT STANDS AT THIS POINT...THINK ITS
ENTIRELY PLAUSIBLE THAT THE SOUTHERN SUBURBS SEE AN INCH OR SO WITH
2-3 INCHES NEAR FISHERS AND NOBLESVILLE. ANY ADDITIONAL TRACK
ADJUSTMENTS WOULD ALTER THAT FURTHER AND FRANKLY HIGHLIGHTS THE
CHALLENGES THIS SYSTEM WILL PROVIDE. VERY LIKELY THAT WE WILL NEED
TO CONSIDER AN ADVISORY LATER TODAY OR TONIGHT FOR THE NORTHEAST
FORECAST AREA CONSIDERING EXPECTED SNOWFALL AND A PERIOD OF BLOWING
SNOW WITH GUSTY WINDS SUNDAY EVENING INTO THE OVERNIGHT AS THE LOW
DEPARTS.

SNOW WILL BE OUT OF THE FORECAST AREA PRIOR TO DAYBREAK MONDAY WITH
A NARROW HIGH PRESSURE RIDGE BUILDING IN. YET ANOTHER SUBTLE PIECE
OF ENERGY WILL DROP THROUGH THE REGION MONDAY EVENING...FURTHER
CARVING OUT THE UPPER TROUGH TO OUR EAST. THIS FEATURE MAY PRODUCE A
FEW LIGHT SNOW SHOWERS MONDAY NIGHT AND EARLY TUESDAY.

TEMPS...TRENDED MUCH CLOSER TO THE COOLER MAVMOS FOR HIGHS BOTH
SUNDAY AND MONDAY. EXPECT HIGHS TO BE REACHED MOST AREAS BY 18Z
SUNDAY WITH FALLING TEMPS THEREAFTER AS COLDER AIR SWEEPS SOUTH.
GENERALLY TOOK A MOS BLEND ON LOWS THROUGH THE PERIOD. MAY SEE TEMPS
RISE A BIT FROM OVERNIGHT LOWS PRIOR TO DAYBREAK SUNDAY WITH WARM
ADVECTION AHEAD OF THE LOW. TEMPS WILL TUMBLE INTO THE TEENS SUNDAY
NIGHT BEHIND THE SYSTEM.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
ISSUED AT 250 AM EST SAT JAN 24 2015

MODELS ARE CLOSE ENOUGH THAT THE SUPERBLEND INITIALIZATION WAS
ACCEPTED FOR MOST ITEMS. A COUPLE OF SYSTEMS WILL MOVE THROUGH A
BROAD UPPER TROUGH ACROSS THE EASTERN PART OF THE COUNTRY.

MODELS TRY TO GENERATE SOME QPF WITH AN EXITING CLIPPER SYSTEM
TUESDAY. ECMWF/GFS DIFFER ON LOCATION AND HOW WIDESPREAD ANY
PRECIPITATION WOULD BE. SYSTEM LOOKS PRETTY WEAK AND MOISTURE IS
LIMITED. RATHER THAN INTRODUCE SLIGHT CHANCE POPS...DECIDED TO
KEEP FORECAST CONSISTENT AND DRY.

MODELS HAVE SPED UP NEXT CHANCE FOR PRECIPITATION.
GFS/ECMWF/CANADIAN AS WELL AS GFS ENSEMBLES NOW SHOW PRECIPITATION
ARRIVING WEDNESDAY NIGHT. THUS ADDED SOME LOW POPS IN FOR WEDNESDAY
NIGHT ALL AREAS. THE SYSTEM WILL MOVE THROUGH THE AREA ON THURSDAY
KEEPING CHANCE POPS IN THE FORECAST.

LOOKS LIKE TEMPERATURES WILL BE COLD ENOUGH FOR SNOW WEDNESDAY NIGHT
WITH READINGS WARMING ENOUGH FOR JUST RAIN FOR MOST OF THURSDAY.

HIGH PRESSURE WILL THEN PROVIDE DRY CONDITIONS ON FRIDAY...BUT MORE
CHANCES FOR PRECIPITATION MAY ARRIVE FOR THE FIRST HALF OF THE
WEEKEND.

TEMPERATURES WILL WARM UP TO ABOVE AVERAGE BY THURSDAY...BUT THEN
COOL TO BELOW AVERAGE AGAIN FOR FRIDAY.

&&

.AVIATION /DISCUSSION FOR 241200Z TAF ISSUANCE/...
ISSUED AT 535 AM EST SAT JAN 24 2015

MVFR RETURNING THIS MORNING...VFR THIS EVENING...MVFR LATE TONIGHT.

SATELLITE IMAGERY SHOWS ANOTHER AREA OF MVFR/LOW VFR CEILINGS
HEADING SOUTHEAST TOWARD THE SITES. SOME OF THE LEADING EDGE IS
DISSIPATING. WITH THIS IN MIND BROUGHT BACK MVFR CEILINGS TO ALL
SITES BY 14-16Z. KBMG/KHUF MAY BE CLOSER TO THE EDGE AND THUS CLOSER
TO VFR. WILL HAVE TO WATCH HOW THINGS DEVELOP.

THIS AREA OF MVFR CEILINGS SHOULD BREAK UP BY EARLY EVENING...BUT
MORE WILL RETURN LATE TONIGHT /CLOSER TO 12Z/ AS AN AREA OF LOW
PRESSURE APPROACHES. FOR KLAF AND THE 30 HOUR KIND TAF...INTRODUCED
VCSH AFTER 10-12Z SUNDAY.

WIDESPREAD PRECIPITATION WILL MOVE INTO THE AREA DURING SUNDAY.

&&

.IND WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

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

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