Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 301913
AFDIND

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

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

&&

.SYNOPSIS...
ISSUED AT 329 AM 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/WEDNESDAY AS A COLD
FRONT MOVES THROUGH CENTRAL INDIANA.

&&

.NEAR TERM /REST OF THIS AFTERNOON/...

ISSUED AT 1239 PM EST FRI JAN 30 2015

UPDATE...THE FORECAST FOR THE REST OF THIS AFTERNOON ONLY NEEDED A
FEW MINOR TWEAKS BASED ON LATEST TRENDS AND OBSERVATIONS.
OTHERWISE IT LOOKS PRETTY MUCH ON TRACK.

ON A MORE NOTEWORTHY SUBJECT...A WINTER STORM WATCH WAS ISSUED. TO
BE CLEAR...*NOT* FOR THIS PERIOD. SPECIFICALLY FOR THE TIME FRAME
OF SATURDAY EVENING THROUGH EARLY MONDAY MORNING FOR COUNTIES
ROUGHLY AROUND AND NORTHWARD OF THE I-70 CORRIDOR. MORE
DISCUSSION/EXPLANATION ON WHY THIS WAS ISSUED WILL COME IN
SUBSEQUENT AFD UPDATES...BUT FOR NOW THIS PRODUCT AND FURTHER
INFORMATION CAN BE FOUND ON OUR WEBSITE AND UNDER THE PRODUCT ID
WSWINDWSW.

THE PREVIOUS DISCUSSION FOLLOWS.

HIGH PRESSURE WILL RESULT IN BENIGN CONDITIONS FOR THE NEAR TERM
PERIOD. THE ONLY EXCEPTION WILL BE SOME POSSIBLE EARLY MORNING
LAKE EFFECT SNOW SHOWERS OVER THE NORTHERN COUNTIES...BUT NO
ACCUMULATIONS ARE EXPECTED. AS SUBSIDENCE STRENGTHENS THROUGH THE
COURSE OF THE DAY...STRATOCUMULUS SHOULD BREAK UP BY THIS
AFTERNOON. HIGHS WILL RANGE FROM THE UPPER 20S TO MID 30S FROM
NORTH TO SOUTH...STUCK CLOSE TO GUIDANCE.

&&

.SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/...

ISSUED AT 329 AM EST FRI JAN 30 2015

THE MAIN FOCUS OF THE SHORT TERM PERIOD IS SNOWFALL AMOUNTS WITH
SYSTEM PROGGED FOR SUNDAY/SUNDAY NIGHT.

FIRST...PARTLY CLOUDY SKIES AND CALM CONDITIONS WILL PREVAIL
TONIGHT THROUGH SATURDAY. HOWEVER...CLOUDS WILL INCREASE ACROSS
THE FORECAST AREA ON SATURDAY AFTERNOON AS A STORM SYSTEM
APPROACHES FROM THE CENTRAL PLAINS. GFS/EURO/NAM ARE ALL IN DECENT
AGREEMENT WITH THE TRACK OF THIS SYSTEM...TAKING THE 700 MB LOW
ACROSS CENTRAL INDIANA. THE OUTLYING MODEL AT THIS TIME IS THE
EURO...WHICH TAKES THE TRACK JUST SLIGHTLY MORE NORTH THAN THE GFS
AND NAM. EITHER WAY THOUGH...EXPECT SIGNIFICANT SNOW ACCUMULATIONS
OVER CENTRAL AND NORTHERN PORTIONS OF CENTRAL INDIANA AS SWATH
BETWEEN -2C AND -8C ISOTHERMS AT 850 MB LINES UP OVER THE NORTHERN
TWO-THIRDS OF THE FORECAST AREA. IN ADDITION...1000-500MB THICKNESS
LINES OF ALL 3 MODELS POINT TO THE CENTRAL AND NORTHERN COUNTIES.
CONFIDENCE IS SLIGHTLY LOWER FOR THE SOUTHERN COUNTIES WHICH COULD
RECEIVE SOME WINTRY MIX WITH JUST THE SLIGHTEST SHIFT OF TRACK TO
THE NORTH.

WESTERN COUNTIES COULD START SEEING SOME SNOWFALL AROUND SUN
00Z...BUT ISENTROPIC LIFT REALLY STRENGTHENS AFTER SUN 06Z. SO
CURRENT THINKING IS HEAVIEST SNOW WILL FALL BETWEEN SUN 12Z-MON
00Z...QUICKLY TAPERING OFF BY MON 06Z.

TEMPS...GENERALLY STUCK CLOSE TO MODEL BLEND WITH A FEW TWEAKS.
TRENDED SLIGHTLY WARMER ON SATURDAY DUE TO SOUTHWESTERLY SURFACE
FLOW AHEAD OF AFOREMENTIONED SYSTEM. THIS WILL HELP BUMP HIGHS UP
INTO THE UPPER 30S. TEMPS WILL FALL BACK TO NORMAL ON SUNDAY
THOUGH AS WINDS BACK TO THE EAST...AND PLUMMET INTO THE SINGLE
DIGITS ON SUNDAY NIGHT AS WINDS BECOME NORTHERLY.

&&

.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 301800Z TAF CYCLE/...

ISSUED AT 1257 PM EST FRI JAN 30 2015

EXPECT VFR CONDITIONS TO CONTINUE...BUT JUST BARELY...AT ALL TAF
SITES DURING THIS CYCLE. CURRENT DECK OF CLOUDS OVER LAF/IND ARE
JUST SLIGHTLY IN THE VFR CATEGORY WITH BKN/OVR CEILINGS IN THE
3100 TO 3300 FOOT RANGE. THERE ARE A COUPLE OBS UPSTREAM OF THESE
TWO SITES THAT ARE DEPICTING CEILINGS AT OR BELOW 3000 FEET...HOWEVER
THOSE SITES ARE MORE ENTRENCHED WITHIN THE CURRENT CLOUD MASS.
WITH LAF/IND BEING ON THE WESTERN FRINGE...DECIDED TO KEEP THEM
VFR. NOT CURRENTLY DEALING WITH MUCH CLOUD COVER OVER HUF/BMG.
HOWEVER...WOULD NOT BE SURPRISED IF BMG GOES SCATTERED THIS
AFTERNOON. EXPECT THIS BAND OF CLOUDS FROM LAF TO IND AND EASTWARD
TO SCATTER LATER THIS AFTERNOON AND EVENING AS DRIER AIR MOVES IN.

THEN THE FOCUS TURNS TO SATURDAY AFTERNOON AND THE APPROACH OF THE
NEXT WEATHER SYSTEM. EXPECT SOME LOWER CEILINGS TO MOVE INTO THE
AREA TOWARD THE END OF THE TAF CYCLE. HOWEVER...DO BELIEVE THAT THE
LOWER MVFR/IFR CEILINGS WILL HOLD OFF UNTIL AFTER THIS PARTICULAR
TAF CYCLE.

AS HIGH PRESSURE CONTINUES TO APPROACH FROM THE WEST...EXPECT NORTH
WINDS TO CONTINUE TO DECREASE AND BECOME LIGHT TONIGHT. INCREASING
BACK TO AROUND 8 TO 10 KNOTS OUT OF THE SOUTHWEST SATURDAY
AFTERNOON.


&&

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

&&

$$

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

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