Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 041846
AFDIND

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
146 PM EST WED MAR 4 2015

.UPDATE...
THE LONG TERM SECTION HAS BEEN UPDATED BELOW.

&&

.SYNOPSIS...
ISSUED AT 340 AM EST WED MAR 4 2015

PRECIPITATION WILL CONTINUE TODAY ACROSS THE SOUTHERN HALF OF
CENTRAL INDIANA AS LOW PRESSURE TRACKS ALONG A NEARLY STATIONARY
BOUNDARY OVER THE TENNESSEE VALLEY. ACCUMULATING SNOW IS POSSIBLE
SOUTH OF I-70 WITH SEVERAL INCHES OVER FAR SOUTHERN PORTIONS OF
CENTRAL INDIANA BY THURSDAY MORNING. STRONG HIGH PRESSURE WILL BRING
DRY WEATHER INTO NEXT WEEK. COLD TEMPERATURES THURSDAY AND FRIDAY WILL
WARM OVER THE WEEKEND...FINALLY RISING ABOVE NORMAL EARLY NEXT
WEEK.

&&

.NEAR TERM /TODAY/...
ISSUED AT 944 AM EST WED MAR 4 2015

CONTINUED TREND OF LOWERING POPS THIS MORNING AS PRECIPITATION HAS
LARGELY STAYED JUST SOUTH OF OUR SOUTHERN BORDER THUS FAR. THIS
WILL CUT DOWN ON EXPECTED SNOW AMOUNTS SLIGHTLY. HRRR BRINGS
SNOWFALL BACK TO THE AREA BY MIDDAY AND WILL BLEND MORNING
ADJUSTMENTS INTO THE AFTERNOON GRIDS. ADDITIONALLY...EXPECT
OVERNIGHT LOWS TO LIKELY REPRESENT OR BE VERY NEAR DAYTIME HIGHS
TODAY AND HAVE ADJUSTED GRIDS IN THAT MANNER. PREVIOUS DISCUSSIONS
FOLLOW.

ISSUED AT 628 AM EST WED MAR 4 2015

LOWERED POPS OVER SOUTHERN COUNTIES FOR MUCH OF THE MORNING BASED ON
CURRENT RADAR TRENDS. MOST OF THE SOUTHERN COUNTIES MAY ACTUALLY
HAVE A PERIOD OF DRY WEATHER BEFORE THE SNOW ARRIVES IN THE
AFTERNOON. ONE INTERESTING NOTE...RAP/HRRR ARE COMING IN FURTHER
SOUTH WITH MORE SUBSTANTIAL SNOWFALL LATER THIS AFTERNOON AND
EVENING. WILL CONTINUE TO MONITOR GOING FORWARD TO SEE IF THESE
TRENDS HOLD.

340 AM DISCUSSION FOLLOWS.

RAIN CONTINUES ACROSS MUCH OF THE SOUTHERN HALF OF THE FORECAST AREA
EARLY THIS MORNING. OBS AND DUAL POL DATA BOTH SHOWING SLEET MIXING
IN WITH THE RAIN ON THE NORTHERN FLANK OF THE PRECIP SHIELD AND EVEN
GETTING A FEW WET SNOWFLAKES MIXING IN AS WELL. TEMPS WERE IN THE
30S...RANGING FROM THE LOWER 30S NORTH TO UPPER 30S OVER THE
SOUTHEAST.

TWO PRIMARY ISSUES TO FOCUS ON OVER THE NEXT 24 HOURS. THE FIRST
DEALS WITH THE ONGOING PRECIP THIS MORNING AS SHALLOW SUBFREEZING
AIR SLOWLY ADVECTS SOUTH BEHIND THE FRONTAL BOUNDARY. THE SECOND
ISSUE THEN FOCUSES ON EXPECTED SNOWFALL AS A SECONDARY WAVE RIDES
ALONG THE BOUNDARY THROUGH THE TENNESSEE VALLEY LATER THIS AFTERNOON
AND TONIGHT. WE WILL DISCUSS EACH IN TANDEM.

STEADIER PRECIP AT 08Z NOW GENERALLY SOUTH OF I-70. LIGHTER ECHOES
EXTEND BACK TO THE NORTHWEST INTO CENTRAL ILLINOIS BUT APPEARS
LITTLE IF ANY OF THIS IS REACHING THE GROUND AT THIS TIME. DOPPLER
RADAR ESTIMATES OF 0.75 TO 1 INCH OVER FAR SOUTHERN COUNTIES SEEM
REASONABLE BUT NOW AS BRIGHT BANDING BECOMES AN ISSUE WITH THE SLEET
MIXING IN...AMOUNTS ARE BECOMING DISTORTED. HAVE ISSUED A FLOOD
ADVISORY FROM DAVIESS CO NORTHEAST THROUGH JENNINGS CO THROUGH
1330Z. COMBINATION OF THIS RAIN WITH THE SNOWMELT IS LIKELY CAUSING
SOME MINOR FLOODING.

RAP AND HRRR GUIDANCE STRUGGLING A BIT WITH PLACEMENT/COVERAGE AREA
OF THE PRECIP AND WITH CURRENT SURFACE TEMPS THIS MORNING. HRRR IN
PARTICULAR HAS PRECIP SHIELD ABOUT 40-50 MILES FURTHER NORTH THAN
WHERE IT IS CURRENTLY. ADDITIONALLY...BOTH MODELS HAVE BEEN TOO
AGGRESSIVE WITH THE ARRIVAL OF THE SUBFREEZING TEMPS SO FAR THROUGH
THE OVERNIGHT...ALTHOUGH MOST RECENT RUNS APPEAR TO BE CAPTURING THE
SLOWER TEMP FALLS BETTER. THESE TWO FACTORS HAVE RESULTED IN BOTH
THE RAP AND HRRR OVERDOING QPF AMOUNTS IN THE FORM OF EITHER LIGHT
ACCUMS OF SLEET OR SNOW ALONG AND JUST SOUTH OF THE I-70 CORRIDOR
THIS MORNING. STILL ANTICIPATE TEMPS TO SLOWLY FALL TO 32 AND LOWER
OVER ALL BUT THE SOUTHERN THIRD OF THE FORECAST AREA BY DAYBREAK...
BUT ANY SLEET OR LIGHT SNOW SHOULD BE MINIMAL AS TEMP FALLS LAG THE
SOUTHWARD SHIFT OF THE PRECIP SHIELD. THE LIGHT WINTRY PRECIP
COMBINED WITH TEMPS FALLING INTO THE UPPER 20S/LOWER 30S WILL CREATE
SLICK CONDITIONS IN SPOTS THROUGH DAYBREAK AND WILL HIGHLIGHT WITH A
SPECIAL WEATHER STATEMENT.

MOST OF THE FORECAST AREA WILL EXPERIENCE A PERIOD OF DRY WEATHER
LASTING THROUGH THE MORNING AS THE FRONT CONTINUES SOUTH. FAR
SOUTHERN COUNTIES HOWEVER WILL CONTINUE TO SEE LIGHT PRECIP THROUGH
THE MORNING...GRADUALLY TRANSITIONING FROM RAIN TO A MIX WITH SLEET
TO ALL SNOW BY EARLY AFTERNOON AS COLDER AIR ADVANCES SOUTH. THE
DEVELOPMENT OF A SECONDARY WAVE ALONG THE FRONT THEN BECOMES THE
PRIMARY FOCUS FOR THE REST OF THE PERIOD...AS PRECIP SHIELD WILL
EXPAND BACK TO THE NORTH IN RESPONSE THE THE BOUNDARY BECOMING
NEARLY STATIONARY OVER THE LOWER TENNESSEE VALLEY. OVERALL MODELS
HAVE COME INTO BETTER ALIGNMENT WITH THE STRONG ARCTIC HIGH TO THE
NORTHWEST HAVING A GREATER INFLUENCE.

BULK OF THE DEEPER MOISTURE AND FORCING WILL REMAIN CLOSER TO THE
OHIO RIVER...AND THIS IS WHERE THE AXIS OF HEAVIEST SNOWFALL SHOULD
SET UP. AMOUNTS WILL GRADUALLY LIGHTEN FURTHER NORTH INTO FAR
SOUTHERN COUNTIES...BUT STILL AM FAIRLY CONFIDENT IN A SWATH OF 3 TO
5 INCHES ALONG AND SOUTH OF A VINCENNES-BLOOMINGTON-GREENSBURG LINE.
POTENTIAL IS THERE FOR PORTIONS OF JACKSON AND JENNINGS COUNTIES TO
MAKE A RUN AT 6 INCHES...BUT CONFIDENCE JUST NOT HIGH ENOUGH TO
SUPPORT A WARNING. AM MORE COMFORTABLE TRANSITIONING THE WATCH TO AN
ADVISORY AND ADDING GREENE/MONROE/BARTHOLOMEW/DECATUR COUNTIES
CONSIDERING AMOUNTS ABOVE. ADVISORY WILL RUN THIS AFTERNOON THROUGH
TONIGHT. FURTHER NORTH...SNOW AMOUNTS WILL DROP OFF RAPIDLY AS DRIER
AIR ASSOCIATED WITH THE HIGH EXERTS ITS INFLUENCE. COULD SEE 1 TO
PERHAPS 1.5 INCHES IN THE INDY METRO AND ALONG THE I-70
CORRIDOR...DIMINISHING TO FLURRIES OVER FAR NORTHERN COUNTIES. SNOW
WILL TAPER OFF FROM NORTHWEST TO SOUTHEAST AFTER 06Z WITH LINGERING
SNOWS CONFINED TO FAR SOUTHEAST COUNTIES AT DAYBREAK THURSDAY.

TEMPS...UTILIZED A BLEND OF SHORT RANGE GUIDANCE AND OBS TO CAPTURE
CURRENT TEMPS AND TRENDS GOING FORWARD THROUGH THE MORNING. MAY SEE
A SUBTLE BUMP OF A DEGREE OR TWO IN TEMPS THIS AFTERNOON OTHERWISE
STRENGTHENING COLD ADVECTION WILL LARGELY ENSURE TEMPS FALLING INTO
THE LOW/MID 20S BY LATE DAY. ENDED UP CLOSER TO METMOS AS A RESULT.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
ISSUED AT 340 AM EST WED MAR 4 2015

FORECAST CHALLENGES ARE MINUSCULE THROUGH THE SHORT TERM AS HIGH
PRESSURE SETTLES IN WITH DRY AND CHILLY WEATHER.

LAST OF THE LIGHT SNOWS WILL SHIFT OUT OF SOUTHEAST COUNTIES BY MID
MORNING THURSDAY. MODEL SOUNDINGS SHOW LINGERING SHALLOW MOISTURE
AND LOW CLOUDS BUT AS PROGRESSIVELY DRIER AIR ADVECTS IN FROM THE
WEST AND THE WAVE AXIS ALOFT PASSES...EXPECT SKIES TO GRADUALLY
CLEAR FROM WEST TO EAST DURING THE AFTERNOON. THE HIGH WILL DRIFT
ACROSS THE REGION THURSDAY NIGHT AND FRIDAY...EVENTUALLY SETTLING
OVER THE LOWER MISSISSIPPI VALLEY BY FRIDAY NIGHT. WILL SEE MAINLY
CLEAR SKIES WITH SUBSIDENCE AND AN ABUNDANCE OF DRY AIR THROUGH THE
COLUMN THROUGH FRIDAY EVENING.

AN UPPER WAVE WITH A SURFACE LOW ACCOMPANYING WILL TRACK THROUGH THE
GREAT LAKES FRIDAY NIGHT AND MAY SPREAD SOME MID AND HIGH CLOUDS
INTO CENTRAL INDIANA. NOT EXPECTING ANY PRECIP AS DEEPER MOISTURE
AND FORCING ALOFT WITH THE SYSTEM WILL REMAIN WELL NORTH OF THE
FORECAST AREA THROUGH DAYBREAK SATURDAY.

TEMPS...ANY SUNSHINE WILL DO VERY LITTLE TO MODIFY THE RENEWED
ARCTIC AIRMASS OVER THE REGION THURSDAY. TEMPS SHOULD REMAIN 25-30
DEGREES BELOW NORMAL IN THE TEENS. COLDEST HIGH RECORD OF 18 FOR
THURSDAY HAS GOOD CHANCE TO BE BROKEN. WITH THE HIGH OVERHEAD
THURSDAY NIGHT AND SNOWPACK STILL ACROSS THE REGION...EXPECT SOME
AREAS TO FALL BELOW ZERO. AS HAS BEEN MENTIONED SHOULD INDY GO
SUBZERO...IT WOULD BE THE FIRST MARCH OCCURRENCE OF A BELOW ZERO
READING IN 31 YEARS. IT MAY ALSO BE THE LAST SUBZERO READING OF THE
SEASON AS CLIMATOLOGY STARTS WORKING AGAINST US AS WE GO INTO MID
MARCH. NEAR MOS GUIDANCE FOR FRIDAY AND FRIDAY NIGHT WITH TEMPS
BEGINNING TO RECOVER.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...

ISSUED AT 145 PM EST WED MAR 4 2015

THIS IS A HIGH CONFIDENCE FORECAST. THE INITIALIZATION FROM THE
REGIONAL SOFTWARE IS ACCEPTED.

THE GFS ENSEMBLE SPREAD IS QUITE LOW FOR THE PERIOD...SO THERE IS A
HIGH CHANCE THE INITIALIZATION WILL VERIFY.

ALSO...WHILE THE EUROPEAN AND GFS MODELS HAVE SOME DIFFERENCES IN
THEIR DETERMINISTIC FIELDS...THEIR STATISTICAL GUIDANCE IS CLOSE. IN
A SENSE IT DOESNT MATTER WHICH VERIFIES BETTER...WE CAN EXPECT THE
SAME SENSIBLE WEATHER EITHER WAY.


&&

.AVIATION /DISCUSSION FOR THE 041800Z TAF ISSUANCE/...

ISSUED AT 1158 AM EST WED MAR 4 2015

AN UPPER LEVEL DISTURBANCE WILL CAUSE SNOW OVER ABOUT THE SOUTHERN
HALF OF THE AREA THIS AFTERNOON. EXPECT CEILINGS AND VISIBILITY TO
BE MAINLY MVFR...BUT IFR AT TIMES. BY 01Z THE SNOW WILL BE
OVER...CEILINGS WILL BE LOW END VFR...AND VISIBILITY SHOULD BE
UNRESTRICTED.

IN THE NORTH THE AFTERNOON SHOULD HAVE CEILINGS AROUND 35 HUNDRED
FEET WITH UNRESTRICTED VISIBILITY.

AS THE UPPER LEVEL DISTURBANCE MOVES AWAY...DURING THE NIGHT CLOUDS
WILL RISE TO NEAR 10 THOUSAND FEET AND THEN BREAK FROM NORTH TO
SOUTH.

WINDS CAN BE EXPECTED TO REMAIN NORTHWEST WITH SPEEDS 10-15 KNOTS
DAYTIME AND 5-10 KNOTS AT NIGHT.


&&

.IND WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 9 AM EST THURSDAY FOR INZ061>065-
067>072.

&&

$$

SYNOPSIS...RYAN
NEAR TERM...RYAN/NIELD
SHORT TERM...RYAN
LONG TERM....JK
AVIATION...JK

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