Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 310403
AFDIND

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
1103 PM EST FRI JAN 30 2015

.UPDATE...

THE AVIATION SECTION HAS BEEN UPDATED BELOW.

&&

.SYNOPSIS...
ISSUED AT 348 PM EST FRI JAN 30 2015

THE MAIN FOCUS OF THE FORECAST PERIOD WILL BE A STORM SYSTEM
PROJECTED TO IMPACT THE AREA MAINLY EARLY SUNDAY THROUGH SUNDAY
NIGHT. MODELS HAVE THE SYSTEM APPROACHING FROM THE SOUTHWEST AND
IT IS EXPECTED TO BRING ACCUMULATING SNOWFALL BEGINNING LATE
SATURDAY NIGHT AND CONTINUING BEFORE EXITING THE REGION MONDAY
MORNING. IN THE WAKE OF THE SYSTEM...BELOW NORMAL TEMPERATURES WILL
PREVAIL ON MONDAY WITH HIGHS ONLY IN THE TEENS. ADDITIONAL
PRECIPITATION CHANCES WILL BE POSSIBLE ON TUESDAY NIGHT AND
WEDNESDAY AS A COLD FRONT MOVES THROUGH CENTRAL INDIANA.

&&

.NEAR TERM /TONIGHT/...
ISSUED AT 956 PM EST FRI JAN 30 2015

GOING FORECAST IN EXCELLENT SHAPE AND NO SIGNIFICANT CHANGES
REQUIRED. SHOULD REMAIN CLEAR OR MOSTLY CLEAR MOST OF THE NIGHT WITH
PERHAPS A FEW HIGH CLOUDS STREAMING ACROSS PORTIONS OF THE AREA
LATE. PREVIOUS DISCUSSION FOLLOWS.

ISSUED AT 348 PM EST FRI JAN 30 2015

FAIRLY QUIET NIGHT TONIGHT...AHEAD THIS LATE WEEKEND/S STORM. HIGH
PRESSURE WILL SLIDE TO THE EAST OF THE AREA. MOSTLY CLEAR SKIES
TONIGHT AND A BLEND OF GUIDANCE FOR TEMPERATURES SEEMS REASONABLE
FOR LOWS IN THE MID TEENS (NORTH) TO LOW 20S (SOUTH).

&&

.SHORT TERM /SATURDAY THROUGH MONDAY/...
ISSUED AT 348 PM EST FRI JAN 30 2015

AS MENTIONED IN UPDATE TO FORECAST EARLIER THIS AFTERNOON A WINTER
STORM WATCH WAS ISSUED FOR ALL COUNTIES ACROSS THE FORECAST
AREA...EXCEPT FOR THE SOUTHERN TWO TIER OF COUNTIES.

THERE IS MEDIUM CONFIDENCE IN THE FORECAST FOR THIS STORM.
YES...DEPENDING ON ANY GIVEN ONE LOCATION...SOME OF THE MODELS
DIFFER WIDELY ON PRECIP/SNOW AMOUNTS WITH ANYTHING FROM 1-2 INCHES
TO A FOOT OF SNOW. HOWEVER THERE IS STILL CONSENSUS AND SOME
CONSISTENCY WITH REGARD TO THE THE MOVEMENT OF THE LOW THROUGH THE
OHIO VALLEY AND THE TIMING OF THE EVENT.

THE MODEL GUIDANCE/SUITE AS A WHOLE HAS TRENDED NORTHWARD AND WETTER
FOR THE MOST PART...SAVE FOR THE GFS WHICH CAME IN SLIGHTLY DRIER
THIS RUN. TIMING LOOKS STILL TO BE BEGIN SATURDAY EVENING AND
LASTING UNTIL THE EARLY HOURS OF MONDAY MORNING...BEFORE THE SYSTEM
FINALLY PULLS AWAY FROM THE CWA. SO THIS IS A FAIRLY LONG DURATION
SNOW EVENT.

THERE IS A SHARP GRADIENT CUT-OFF WITH POPS WHICH ONCE AGAIN
MYSTERIOUSLY FALLS ROUGHLY ALONG/AROUND THE I-70 CORRIDOR...A
PHENOMENON IN WHICH FORECASTERS IN CENTRAL INDIANA ARE QUITE
FAMILIAR WITH. THE WINTER STORM WATCH WAS ISSUED FOR AROUND THIS
CUT-OFF ZONE AND NORTHWARD. AND THIS WAS BASED ON AN AVERAGE OF THE
THE EURO/SREF/NAM AND GFS AMOUNTS WHICH ARE IN GOOD/SIMILAR
AGREEMENT AND AMOUNTED TO A MEAN OF 6-9 INCHES BEING POSSIBLE
WITHIN THE WATCH AREA...AT THIS TIME OF ISSUANCE. WITH OF COURSE THE
HIGHEST AMOUNTS ACROSS THE NORTHERN COUNTY WARNING AREA.

OTHER THAN THE HEAVIER SNOW AMOUNTS BEING THE BIG STORY...THE
OTHER SIGNIFICANT STORY IS THE COUNTIES FOR SOUTH OF THE WATCH
AREA. AS THE GUIDANCE CAME IN THIS ROUND WITH A NORTHWARD
TREND...IT IS ALSO MUCH WARMER THAN PREVIOUSLY FORECAST. FIRST...A
FEW LIGHT RAIN SHOWERS MAY BE POSSIBLE BEFORE THIS SYSTEM EVEN
ARRIVES SATURDAY EVENING AND THE PRECIPITATION TYPE ON SATURDAY
NIGHT INTO EARLY SUNDAY LOOKS TO BE ALL SNOW. HOWEVER...SURFACE
TEMPERATURES AND THICKNESSES HAVE WARMED SO THAT A SNOW/RAIN MIX IS
NOW POSSIBLE ACROSS THE SOUTHERN COUNTIES MAINLY DURING SUNDAY
AFTERNOON. THIS WAS ACCOUNTED FOR AND THE FORECAST WAS UPDATED TO
REFLECT SNOW LIKELY WITH A CHANCE OF RAIN MIXING IN SUNDAY
AFTERNOON/EARLY EVENING. THIS WILL KNOCK DOWN SNOW TOTALS ACROSS
THIS AREA CONSIDERABLY...TO 1-4 INCHES...WHICH IS QUITE A DIFFERENCE
FROM THE SNOW TOTALS PREDICTED IN THE WATCH AREA...HENCE THE SHARP
SNOWFALL GRADIENT CUT-OFF MENTIONED EARLY. FOR NOW WILL MENTION THIS
IN THE HWO AND THE WX STORY AS THIS DOES NOT WARRANT ANY TYPE OF
STATEMENT AT THIS TIME.

FINALLY...THE SYSTEM LOOKS TO MOVE AWAY FROM THE AREA BY MONDAY
MORNING AND THE FORECAST FOR THE REST OF THE DAY LOOKS DRY. IT
DOES NOT APPEAR ANY WRAP AROUND SNOW SHOWERS OR FLURRIES ARE EVEN
POSSIBLE BY THE WAY THE THE SYSTEM APPEARS TO ACCELERATE FROM THE
AREA AND COLDER AND MUCH DRIER AIR (COLD AIR ADVECTION) BEGINS TO
FLOW OVER THE AREA IN EARNEST BY MONDAY AFTERNOON AND EVENING.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
ISSUED AT 204 PM EST FRI JAN 30 2015

ECMWF AND GFS AGREE ON A PERSISTENT COLD PATTERN AS NORTHWEST FLOW
IS PERSISTENT ALOFT. IN THE WAKE OF THE COLD FRONT ON MONDAY THE
FIRST OF TWO ARCTIC AIR MASSES IS EXPECTED TO SETTLE ACROSS THE
OHIO VALLEY...BRINGING DRY AND COLD WEATHER.

A WEAK COLD FRONT IS EXPECTED TO PUSH ACROSS THE AREA ON
WEDNESDAY...HOWEVER THE AIR MASS AHEAD AND BEHIND THIS SYSTEM
REMAIN QUITE DRY. FURTHERMORE...DYNAMICS ALOFT APPEAR VERY
LIMITED. THUS AS THIS SYSTEM PASSES ANY SNOWFALL THAT WILL OCCUR
SHOULD BE LIGHT. IN THE WAKE OF THE COLD FRONT YET ANOTHER ARCTIC
HIGH PRESSURE SYSTEM IS SET TO MOVE IN TO THE AREA...WITH ANOTHER
BLAST OF COLD AIR ADVECTION.

GIVEN THE COLD AIR ADVECTION THROUGH THE PERIOD AND THE
EXPECTATION OF SNOW ON THE GROUND FROM PREVIOUS SYSTEMS...HAVE
TRENDED TEMPS COOLER THAN MAVMOS.

&&

.AVIATION /DISCUSSION FOR THE 310600Z TAFS/...
ISSUED AT 1103 PM EST FRI JAN 30 2015

NO SIGNIFICANT CLOUD COVER AND UNRESTRICTED VISIBILITY EXPECTED AT
THE TAF SITES THROUGH 311800Z.

LIGHT SURFACE WINDS OVERNIGHT EXPECTED TO BECOME 200-220 DEGREES AT
8-12 KTS BY LATE MORNING SATURDAY.

&&

.IND WATCHES/WARNINGS/ADVISORIES...

WINTER STORM WATCH FROM SATURDAY EVENING THROUGH MONDAY MORNING
FOR INZ021-028>031-035>049-051>057.

&&

$$

SYNOPSIS...SMF
NEAR TERM...SMF/NIELD
SHORT TERM...SMF
LONG TERM...PUMA
AVIATION...JAS

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