Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 260431
AFDIND

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
1131 PM EST WED FEB 25 2015

.UPDATE...
THE AVIATION SECTION HAS 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 /REST OF TONIGHT THROUGH THURSDAY/...

ISSUED AT 942 PM EST WED FEB 25 2015

UPDATE...
CURRENT RADAR MOSAIC IS SHOWING RETURNS OVER NORTHWEST AND WESTERN
PORTIONS OF CENTRAL INDIANA...BUT SURFACE OBS ARE ONLY REPORTING
SNOW ACROSS THE NORTHWEST QUADRANT. LOW LEVEL DRY LAYER SEEMS TO
BE INHIBITING SNOW ALREADY IN THE TERRE HAUTE AREA AS MENTIONED IN
EARLIER DISCUSSION. SNOW WILL SPREAD FROM NORTHWEST TO SOUTHEAST
THROUGH THE NIGHT...WITH THE HIGHEST ACCUMULATIONS STILL EXPECTED
TO BE NORTH OF A TERRE HAUTE...CRAWFORDSVILLE...KOKOMO LINE. AREAS
NORTH OF THAT LINE CAN STILL EXPECT 1 TO 2 INCHES OF SNOW
ACCUMULATION. ELSEWHERE...UP TO AN INCH OF SNOWFALL CAN BE
EXPECTED ACROSS THE CENTRAL PORTIONS OF THE FORECAST AREA WITH
LESSER AMOUNTS ACROSS THE SOUTHERN COUNTIES.

OVERNIGHT LOWS ARE EXPECTED TO FALL INTO THE TEENS. CURRENTLY...TEMPS
ARE GENERALLY IN THE 20S WITH NORTHEAST WINDS OF 5 TO 10 MPH.
UPDATED GRIDS HAVE BEEN SENT.

PREVIOUS DISCUSSION...
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 260600 TAF ISSUANCE/...

ISSUED AT 1126 PM EST WED FEB 25 2015

VFR CONDITIONS QUICKLY HAVE/HAD DETERIORATED TO MVFR...POSSIBLY IFR
AT TIMES THROUGH THIS MORNING. BACK TO MVFR FOR MAJORITY OF THE
REST OF THE DAY AND POSSIBLY A RETURN TO VFR AFTER 06Z FRIDAY.

ANOTHER CLIPPER SYSTEM WILL MOVE ACROSS CENTRAL INDIANA THROUGH
EARLY TODAY. BEST FORCING WITH THE SHORT WAVE APPROACHES
IN THE NEXT FEW HOURS...SNOW IS EXPECTED TO CONTINUE TO DEVELOP
AND CIGS WILL BECOME MVFR AS THIS AREA DRIFT FARTHER TO THE SOUTH.
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...HOWEVER MVFR CEILINGS APPEAR LINGER ON INTO
THIS EVENING AS DEPICTED IN THE TAFS NOW...AND POSSIBLY MAY LIFT
BACK TO VFR SOMETIME AROUND 06Z FRIDAY.

&&

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

$$

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

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