Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 242030
AFDIND

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
330 PM EST TUE FEB 24 2015

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

&&

.SYNOPSIS...
ISSUED AT 247 PM EST TUE FEB 24 2015

A WEAK UPPER TROUGH IS EXPECTED TO MOVE ACROSS THE AREA LATE THIS
AFTERNOON AND INTO THE EVENING HOURS. ANOTHER WEATHER DISTURBANCE
IS EXPECTED TO PASS OVER THE AREA FROM WEDNESDAY NIGHT THROUGH
THURSDAY NIGHT. A THIRD SYSTEM MAY AFFECT THE AREA BY LATE IN THE
WEEKEND AND INTO EARLY NEXT WEEK.

&&

.NEAR TERM /REST OF THIS AFTERNOON AND TONIGHT/...
ISSUED AT 247 PM EST TUE FEB 24 2015

SHORT WAVE TROUGH CURRENTLY DROPPING THROUGH THE SOUTHERN GREAT
LAKES EXPECTED TO PASS OVER THE LOCAL AREA LATE THIS AFTERNOON AND
EVENING. BEEN SOME FLURRIES ASSOCIATED WITH THIS FEATURE...BUT NOT
MUCH ELSE. WILL KEEP A CHANCE OF FLURRIES GOING THROUGH ABOUT
250500Z. SKIES SHOULD CLEAR OFF RATHER RAPIDLY DURING THE PRE DAWN
HOURS OF WEDNESDAY IN THE WAKE OF THE TROUGH.

APPEARS THE GFS MOS LOWS FOR TONIGHT LOOK A BIT ON THE COOL SIDE
BASED ON PROGGED LOW LEVEL THICKNESSES. WILL NUDGE UP THE GUIDANCE A
BIT.

&&

.SHORT TERM /TUESDAY THROUGH FRIDAY/...
ISSUED AT 247 PM EST TUE FEB 24 2015

THE MAIN WEATHER MAKER DURING THIS PERIOD WILL BE A PAIR OF SHORT
WAVES TROUGH IN A SPLIT FLOW PATTERN DURING THE WEDNESDAY NIGHT TO
THURSDAY NIGHT TIME FRAME. THE SOUTHERN STREAM SYSTEM IS EXPECTED TO
MOVE OVER THE SOUTHERN PARTS OF THE COUNTRY...WHILE A NORTHERN
SYSTEM IS EXPECTED TO DROP INTO THE GREAT LAKES.

MODEL DATA SUGGEST MOST OF THE MOISTURE WILL BE TIED UP WITH THE
SOUTHERN STREAM SYSTEM. OPERATIONAL MODELS ARE LIMITED WITH THE
MOISTURE ASSOCIATED WITH THIS SYSTEM. HOWEVER THE ENSEMBLES ARE IN
GENERAL ARE A BIT WETTER THAN THE OPERATIONAL MODELS...SUGGESTING
LIGHT ACCUMULATIONS OF SNOW ARE POSSIBLE.

WILL GO WITH CHANCE POPS FOR SNOW STARTING LATE WEDNESDAY NIGHT INTO
THURSDAY. MOST OF THE MOISTURE/LIFT APPEARS TO EXIT THE AREA BY
THURSDAY EVENING...HOWEVER ENSEMBLES SUGGEST A LINGERING CHANCE
INTO THURSDAY NIGHT AS WELL. WILL KEEP SOME SMALL CHANCE POPS IN THE
FORECAST THURSDAY NIGHT TO COVER THE POTENTIAL FOR A SLOWER
SOLUTION.

BASED ON PROGGED LOW LEVEL THICKNESSES...THE GFS MOS TEMPERATURE
GUIDANCE IN THE WEDNESDAY THROUGH THURSDAY PERIODS LOOK TOO COOL.
WILL RAISE THE NUMBERS A FEW DEGREES IN THOSE PERIODS. THE GUIDANCE
LOWS BY THURSDAY NIGHT LOOK OK AT THIS TIME.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
ISSUED AT 242 PM EST TUE FEB 24 2015

PRIMARY FOCUS FOR THE EXTENDED CONTINUES TO BE ON COMPLEX AND
PROLONGED PERIOD OF PRECIPITATION SET TO IMPACT THE OHIO VALLEY AS
A SERIES OF WAVES TRACKS THROUGH THE REGION.

THE WEEKEND WILL START DRY AND BITTERLY COLD WITH STRONG HIGH
PRESSURE SLOWLY MOVING AWAY TO THE EAST. ONE MORE SUBZERO NIGHT
CERTAINLY APPEARS PLAUSIBLE FRIDAY NIGHT WITH THE HIGH CENTERED
JUST TO OUR EAST. CLOUDS WILL GRADUALLY INCREASE LATE SATURDAY
WITH LIGHT SNOW DEVELOPING SATURDAY NIGHT. EXTENDED MODELS
CONTINUE TO ADJUST TO A PATTERN SHIFT ALOFT AS UPPER WAVE TRACKING
OUT OF THE PACIFIC NORTHWEST CARVES OUT A DEEP TROUGH OVER THE
WESTERN U S. DOWNSTREAM OF THE TROUGH...QUASI- ZONAL TO SOUTHWEST
FLOW WILL DOMINATE EAST OF THE ROCKIES...PUMPING IN PROGRESSIVELY
DEEPER MOISTURE INTO THE OHIO AND TENNESSEE VALLEY BEGINNING
SATURDAY NIGHT AND CONTINUING INTO EARLY NEXT WEEK.

WHILE DETAILS REMAIN MURKY AT THIS EARLY STAGE...SOME NOTICEABLE
TRENDS HAVE STARTED TO DEVELOP OVER THE LAST COUPLE MODEL RUNS.
BULK OF THE MODELS ARE COLDER IN THE BOUNDARY LAYER FOR SUNDAY AND
MONDAY. A COUPLE OF REASONS FOR THIS...MORE ENERGY ALOFT IS BEING
HELD BACK IN THE WESTERN TROUGH...LEADING TO A BROAD OVERRUNNING
SETUP AS OPPOSED TO A STRONGER SYSTEM TRACKING THROUGH THE OHIO
VALLEY LATE WEEKEND. ADDITIONALLY...PRESENCE OF A SECONDARY AREA
OF HIGH PRESSURE POISED TO SINK INTO THE MID MISSISSIPPI VALLEY BY
THE END OF THE WEEKEND. BOTH OF THESE FACTORS SUPPORT MORE
SUPPRESSION AND CONSEQUENTLY A COLDER SCENARIO. HAVE TRENDED
TOWARDS MORE SNOW THROUGH MONDAY AND LIMITED ANY MIXING TO
SOUTHERN COUNTIES. CONSIDERING THE DIFFICULTY THE MODELS HAVE HAD
IN PROPERLY SAMPLING THE SNOWPACK AND ITS IMPACTS ON NEAR SURFACE
TEMPS...MAY SEE FURTHER ADJUSTMENTS TOWARDS COLDER BOUNDARY LAYER
CONDITIONS IN THE COMING DAYS.

A MORE ROBUST PIECE OF ENERGY EJECTS OUT MONDAY NIGHT AND IS
LIKELY TO DEVELOP A SURFACE WAVE INTO THE OHIO AND TENNESSEE
VALLEYS TUESDAY AS THE UPPER JETS PHASE. THIS SYSTEM DEPENDING ON
ITS TRACK HAS A MUCH BETTER OPPORTUNITY TO PULL WARMER AIR ALOFT
NORTH INTO THE REGION AND CREATE A SLOPPY WINTRY MIX. INTERESTING
TO NOTE AT THIS PRELIMINARY STAGE THAT MODEL CONSENSUS TAKES THE
WAVE JUST SOUTH OF THE FORECAST AREA. WILL CARRY A MIX FOR MOST OF
THE AREA TUESDAY BUT ANY SHIFT FURTHER SOUTH TO THE SYSTEM WOULD
INTRODUCE A GREATER THREAT FOR SNOW. STILL SEVERAL DAYS AWAY FROM
STARTING TO HONE IN ON SPECIFICS WITH THIS SYSTEM.

&&

.AVIATION /DISCUSSION FOR THE 24/2100Z TAF UPDATE/...

ISSUED AT 322 PM EST TUE FEB 24 2015

UPDATE...
NO CHANGES.

PREVIOUS DISCUSSION...
MVFR CEILINGS DEVELOPING THIS EVENING THROUGH EARLY TWEDNESDAY...
OTHERWISE VFR CONDITIONS EXPECTED.

FRONTAL BOUNDARY APPROACHING FROM THE NORTHWEST AS LOW PRESSURE
TRACKS INTO THE NORTHERN GREAT LAKES. MID AND HIGH LEVEL CLOUDS
WILL GRADUALLY EXPAND THROUGH THE AFTERNOON WITH VFR STRATOCU
DEVELOPING BY EARLY EVENING. HI RES GUIDANCE DOES INDICATE
POTENTIAL FOR A FLURRIES/FEW SNOW SHOWERS WITH KIND AND KLAF BEING
THE SITES WITH THE GREATEST CHANCE TO BE IMPACTED. EXPECT SNOW TO
BE LIGHT AND WIDELY SCATTERED AND CARRYING JUST A VCSH AT THESE
TERMINALS DURING THE EVENING. GUSTY SOUTHWEST WINDS WILL VEER TO
WEST/NORTHWEST BY LATE EVENING.

MODEL SOUNDINGS AND RH PROGS SUPPORT EXPANSION OF MVFR STRATOCU
LATE THIS EVENING INTO THE OVERNIGHT AS WEAK COLD ADVECTION
DEVELOPS. WEAK HIGH PRESSURE BUILDING IN LATE MAY HELP TO SCATTER
LOW CEILINGS AT BOTH KHUF AND KLAF. THE HIGH WILL SHIFT EAST
QUICKLY WEDNESDAY MORNING WITH MID LEVEL CLOUDS ARRIVING FROM THE
WEST BY MIDDAY IN ADVANCE OF A CLIPPER MOVING INTO THE MISSOURI
VALLEY. WINDS WILL SHIFT TO N/NW WEDNESDAY MORNING THEN BECOME
LIGHT AND VARIABLE.


&&

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

&&

$$

SYNOPSIS...JAS
NEAR TERM...JAS
SHORT TERM...JAS
LONG TERM....RYAN
AVIATION...RYAN/TDUD

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