Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 252034
AFDIND

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
334 PM EST WED FEB 25 2015

.UPDATE...

THE SYNOPSIS...NEAR TERM AND SHORT TERM SECTIONS HAVE BEEN
UPDATED BELOW.

&&

.SYNOPSIS...
ISSUED AT 334 PM EST WED FEB 25 2015

A WEAKENING CLIPPER SYSTEM WILL PASS THROUGH THE AREA TONIGHT
INTO THURSDAY...BRINGING LIGHT SNOWFALL TO THE AREA...WITH A
REINFORCING SHOT OF COLD AIR IN ITS WAKE AS YET ANOTHER CANADIAN
HIGH DROPS INTO THE CENTRAL PART OF THE NATION. A FRONTAL ZONE IN
COMBINATION WITH A COUPLE OF ADDITIONAL DISTURBANCES WILL PROVIDE
OPPORTUNITIES FOR PRECIPITATION OVER THE WEEKEND AND AGAIN EARLY
NEXT WEEK. PRECIPITATION TYPES WITH THOSE SYSTEMS REMAIN HIGHLY
UNCERTAIN AT THIS TIME.

&&

.NEAR TERM /TONIGHT AND THURSDAY/...
ISSUED AT 334 PM EST WED FEB 25 2015

GRADUALLY WEAKENING CLIPPER SYSTEM WILL MOVE INTO THE AREA
TONIGHT INTO THURSDAY. WHILE THERE WILL LIKELY BE SOME MESOSCALE
FORCING IN THE FORM OF WEAK FRONTOGENESIS...IT IS UNREMARKABLE AND
WILL ALSO HAVE TO CONTEND WITH SUBSTANTIAL LOW LEVEL DRY LAYER
APPARENT ON ILX/ILN MORNING RAOBS. THUS...DO NOT EXPECT MORE THAN
A LIGHT ACCUMULATION OUT OF THIS EVENT...MAINLY ACROSS THE
NORTHERN HALF OR SO OF CENTRAL INDIANA. MOST ALL GUIDANCE LINES UP
WELL WITH THE FINAL FORECAST...AND SUGGESTS UP TO 1-2 INCHES
ACROSS THE NORTHWESTERN PORTION OF CENTRAL INDIANA...WITH UP TO AN
INCH ALONG A TERRE HAUTE TO INDY AND MUNCIE LINE...AND A HALF INCH
OR LESS ACROSS THE SOUTHERN PORTIONS OF CENTRAL INDIANA. THIS MAY
PRODUCE A FEW SLICK SPOTS FOR THE THURSDAY MORNING COMMUTE BUT
THAT SHOULD BE ABOUT THE EXTENT OF IT.

ON TEMPS...BUMPED UP CONSENSUS MINS AS BETWEEN CLOUD
COVER...INCOMING PRECIP...AND THE FACT THAT MORE SUBSTANTIAL COLD
ADVECTION DOES NOT BEGIN UNTIL DAYTIME THURSDAY...CONSENSUS MAX
TEMPS LOOKED REASONABLE.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
ISSUED AT 334 PM EST WED FEB 25 2015

EXPECT DRY CONDITIONS DURING THE SHORT TERM WITH THE EXCEPTION OF
A FEW FLURRIES EARLY THURSDAY EVENING. THIS LEAVES TEMPS AS THE
ONLY MAJOR FORECAST VARIABLE.

CONSENSUS NUMBERS APPEARED REASONABLE FOR MAX TEMPS FRIDAY AND
SATURDAY. MIN TEMPS REQUIRED A BIT MORE MASSAGING AS THEY APPEARED
A BIT WARM THURSDAY AND FRIDAY NIGHTS...BUT DID NOT MAKE HUGE
CHANGES AS GUIDANCE HAS STRUGGLED SIGNIFICANTLY WITH THE LAST
COUPLE OF ARCTIC INTRUSIONS. SUBZERO TEMPS WILL BE IN PLAY AGAIN
THURSDAY AND FRIDAY NIGHTS.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
ISSUED AT 203 PM EST WED FEB 25 2015

VERY ACTIVE WEATHER PATTERN ANTICIPATED DURING THIS PERIOD.

AFTER A DRY SATURDAY AS HIGH PRESSURE DEPARTS THE AREA GFS AND
ECMWF AGREE THAT A STRONG SHORT WAVE WILL PUSH THROUGH THROUGH THE
GREAT LAKES. STRONG HIGH PRESSURE OVER CAROLINAS WILL PROVIDE AN
FAVORABLE LOWER LEVEL FLOW TO BRING MOISTURE INTO THE SYSTEM ALONG
WITH WARMER AIR. MODELS SUGGEST A BAROCLINIC ZONE SETTING UP OVER
INDIANA ON SUNDAY AS THE SHORT WAVE PASSES. ULTIMATELY THIS LOOKS
LIKE A CLASSIC OVERRUNNING SITUATION WITH GOOD MOISTURE AND GOOD
FORCING. THUS HAVE RAMPED UP POPS TO THE LIKELY CATEGORY AS THESE
FEATURES PASS ON SUNDAY INTO SUNDAY NIGHT. ENOUGH WARM AIR MAY BE
PRESENT ACROSS THE SOUTHERN PARTS OF THE FORECAST AREA FOR PRECIP
TO FALL AS RAIN...HOWEVER AT THIS TIME FORECAST SOUNDINGS ARE
TRENDING TOWARD A BELOW FREEZING COLUMN FOR SUNDAY NEAR IND. LOTS
OF TIME AND FURTHER RUNS TO LOOK AT BEFORE THIS SYSTEM
ARRIVES...AND UNCERTAINTY WITH PRECISE POSITION OF THE HIGHLY
IMPACTFUL FREEZING LINE REMAINS HIGH AT THIS TIME.

QUIET WEATHER REMAINS ON MONDAY AS THE SHORT WAVE OVER THE GREAT
LAKES IS EXPECTED TO DEPART AS UPPER RIDGING BUILDS ACROSS THE
REGION. GFS THEN SUGGESTS A DEEPER TROUGH FOR TUESDAY OVER THE
WESTERN UNITED STATES EJECTING A SHORT WAVE TOWARD THE PLAINS
STATES AND OHIO VALLEY FOR TUESDAY NIGHT AND WEDNESDAY WITH
FAVORABLE WARMER SOUTHERLY SURFACE FLOW AHEAD OF THIS SYSTEM. WILL
ONCE AGAIN HAVE POPS IN THE FORECAST. HOWEVER THE HANDLING OF THIS
SECOND SYSTEM STILL SEEMS A BIT DEPENDENT UPON THE FIRST.

&&

.AVIATION /DISCUSSION FOR THE 25/21Z TAF UPDATE/...
ISSUED AT 334 PM EST WED FEB 25 2015

NO CHANGES REQUIRED. PREVIOUS DISCUSSION FOLLOWS.

ISSUED AT 1146 AM EST WED FEB 25 2015

VFR CONDITIONS DETERIORATING TO MVFR THIS OVERNIGHT.

SATELLITE SHOWS HIGH CLOUDS FROM A STORM SYSTEM OVER THE
MISSISSIPPI RIVER VALLEY SPREADING NORTHEAST. ANOTHER CLIPPER LOW
PRESSURE SYSTEM WAS FOUND ACROSS SE NEBRASKA...DIVING SOUTHEAST.
CLOUDS FROM THE SOUTH AND THE APPROACHING SYSTEM FROM THE
NORTHWEST ARE EXPECTED TO RESULT IN LOWERING CIGS THROUGH THE EVENING.
 AS BEST FORCING WITH THE SHORT WAVE APPROACHES OVERNIGHT...SNOW
IS EXPECTED TO DEVELOP AND CIGS WILL BECOME MVFR. TIME HEIGHTS AND
FORECAST SOUNDINGS REVEAL A SATURATED COLUMN BY 12Z
THURSDAY...WITH SOME IMPROVEMENT TOWARD 18Z AS THE SHORT WAVE AND
FORCING DEPARTS. THUS WILL TREND TOWARD ENDING THE SNOW WINDOW BY
MID/LATE MORNING.

&&

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

&&

$$

SYNOPSIS...NIELD
NEAR TERM...NIELD
SHORT TERM...NIELD
LONG TERM...PUMA
AVIATION...JP/TDUD

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