Area Forecast Discussion
Issued by NWS Indianapolis, IN

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146
FXUS63 KIND 120818
AFDIND

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
316 AM EST FRI FEB 12 2016

.UPDATE...
THE LONG TERM AND AVIATION SECTIONS HAVE BEEN UPDATED BELOW

&&

.SYNOPSIS...
ISSUED AT 330 PM EST THU FEB 11 2016

A COLD UPPER TROUGH OVER ONTARIO AND THE ST. LAWRENCE VALLEY WILL KEEP US
UNDER A NORTHWEST FLOW ALOFT AND TEMPERATURES COLDER THAN NORMAL THROUGH
EARLY NEXT WEEK.  A CLIPPER WILL GIVE US A CHANCE OF LIGHT SNOW TOWARDS
DAYBREAK OVER WESTERN SECTIONS AND MOST AREAS FRIDAY.  LAKE EFFECT
SNOW SHOWERS MAY LINGER TO MIDDAY SATURDAY ACROSS OUR NORTHEAST.

COLD HIGH PRESSURE WILL BUILD EAST ACROSS OUR REGION SATURDAY AND
SATURDAY NIGHT.  AN APPROACHING AREA OF LOW PRESSURE WILL SPREAD
SNOW ACROSS OUR REGION SUNDAY INTO MONDAY.   ANOTHER SYSTEM WILL
BRING A CHANCE OF SNOW MONDAY AND MONDAY NIGHT.  FINALLY A FOURTH
SYSTEM WILL BRING A CHANCE OF SNOW OR MIXED PRECIPITATION AROUND THE
MIDDLE OF NEXT WEEK. TEMPERATURES WILL BETENTIALGIN TO MODERATE
TOWARDS THE MIDDLE OF NEXT WEEK AS OUR UPPER FLOW BECOMES MORE
ZONAL.

&&

.NEAR TERM.../TONIGHT AND FRIDAY/
ISSUED AT 822 PM EST THU FEB 11 2016

GOING FORECAST IS IN EXCELLENT SHAPE. FLAKES MAY FLY ACROSS PORTIONS
OF CENTRAL INDIANA BY THE MORNING RUSH. FEEL CHANCE POPS HANDLE THIS
BEST HOWEVER AS THERE IS A LOT OF NEAR SURFACE DRY AIR TO OVERCOME.
WILL HAVE TO MONITOR FOR POSSIBLE IMPACTS TO FRIDAY MORNING COMMUTE
ACROSS THE AREA...ESPECIALLY AS HRRR AND NAM PROFILES INDICATE FIRST
FLAKES MAY BEGIN REACHING THE GROUND DURING THE HEART OF THE
COMMUTE. HOWEVER...RATES APPEAR UNLIKELY TO BE SUCH THAT RAPID
ACCUMULATION WOULD OCCUR...WHICH WOULD LIMIT POTENTIAL IMPACT.

PREVIOUS DISCUSSION FOLLOWS.

ISSUED AT 330 PM EST THU FEB 11 2016

HIGH PRESSURE CENTERED OVER ILLINOIS WILL MOVE EAST ACROSS INDIANA THIS
EVENING AND ON TO THE EAST BY MONDAY.   A WEAK CLIPPER OVER THE UPPER
MIDWEST AND NORTHERN PLAINS WILL MOVE TO THE MIDDLE MISSISSIPPI VALLEY
LATE TONIGHT AND ACROSS THE OHIO VALLEY FRIDAY.

MOSTLY CLEAR CONDITIONS WERE OCCURRING ACROSS WESTERN SECTIONS THIS AFTERNOON
WHILE PARTLY CLOUDY CONDITIONS WERE THE RULE IN THE EAST.   MID/HIGH CLOUDS
OVER THE MIDDLE MISSISSIPPI VALLEY WILL MOVE OUR WAY AND THICKEN OVERNIGHT.
ANY SNOW FROM THE CLIPPER PROBABLY WON`T REACH OUR AREA UNTIL AFTER 09Z AND
THIS WILL BE MAINLY ACROSS WESTERN AND SOUTHWEST AREAS.

SCATTERED LIGHT SNOW SHOWERS WILL SPREAD EAST ACROSS OUR REGION FRIDAY. AMOUNTS
WILL BE GENERALLY A QUARTER INCH. BUT SOME LAKE EFFECT SNOW SHOWERS ARE POSSIBLE
ACROSS OUR NORTHEAST LATE FRIDAY AS OUR FLOW BECOMES MORE NORTHERLY AND AMOUNTS
THERE WILL BE A LITTLE HIGHER BY LATE FRIDAY.

LOWERED TEMPERATURES SLIGHTLY CENTRAL AND EAST TONIGHT AS HIGH PRESSURE WILL
PROVIDE GOOD RADIATIONAL COOLING EARLY ON.  OTHERWISE...A MOS BLEND OF TEMPERATURES
SEEM REASONABLE.   WINDS WILL BE LIGHT TONIGHT AND THEN BECOME NORTHWEST WITH
GUSTS UP TO 25 MPH BY FRIDAY AFTERNOON AS A PRESSURE GRADIENT STRENGTHENS.

&&

.SHORT TERM.../FRIDAY NIGHT THROUGH SUNDAY/
ISSUED AT 330 PM EST THU FEB 11 2016

WE WILL REMAIN UNDER A COLD NORTHWEST FLOW FRIDAY NIGHT SATURDAY AS HIGH
PRESSURE OVER THE NORTHERN PLAINS BUILDS OUR WAY.  MODELS INDICATE SOME FETCH OFF
OF LAKE MICHIGAN WHICH WILL PRODUCE SCATTERED LAKE EFFECT SNOW SHOWERS OVER
NORTHEAST SECTIONS.  WHILE COLD AND DRY WEATHER WILL BE THE RULE ELSEWHERE.

MODELS INDICATE 850 TEMPERATURES OF -15 TO -21 CELSIUS SATURDAY AND -8 TO -12
CELSIUS SUNDAY.  THIS WILL TRANSLATE TO HIGHS IN THE TEENS SATURDAY 20 TO 26
DEGREES SUNDAY.   LOWS WILL BE MOSTLY IN THE SINGLE DIGITS BOTH FRIDAY AND
SATURDAY NIGHT.  BUT LOWS NEAR ZERO ARE POSSIBLE SATURDAY NIGHT OVER NORTHEAST
SECTIONS AS CLOUDS MAY NOT ARRIVE THERE UNTIL LATE.

THE BIGGEST CONCERN WILL BE SNOW AMOUNTS SUNDAY AS AREA OF LOW PRESSURE MOVES
INTO THE UPPER MIDWEST AND A STRONGER CLIPPER MOVES OUR WAY.  THE NAM/OPERATIONAL
GFS AND THE NEW EURO ALL INDICATE AN INCH OR TWO OF SNOW BY SUNDAY AFTERNOON...
WHILE THE CANADIAN HARDLY HAS ANYTHING AS MOST OF ITS PRECIPITATION IS FARTHER
SOUTHWEST.  FOR NOW WILL GO WITH A BLEND.  WILL RAISE POPS TO LIKELY OVER WEST
CENTRAL AND NORTHWEST AND GO WITH HIGH CHANCE POPS ELSEWHERE BY SUNDAY AFTERNOON.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
ISSUED AT 316 AM EST FRI FEB 12 2016

A LOT OF MOVING PARTS IN REGARDS TO THE EARLY WEEK SYSTEM POISED
TO AFFECT THE EASTERN U S AND THE 00Z MODEL SUITE DID LITTLE TO
INCREASE THE LOW CONFIDENCE IN HIGHLIGHTING SPECIFIC IMPACTS TO
CENTRAL INDIANA. THE EXTENDED PERIOD WILL BE ACTIVE WITH VARIOUS
SNOW THREATS THROUGH MIDWEEK BEFORE A WARMING TREND COMMENCES FOR
THE SECOND HALF OF THE WEEK.

NORTHERN STREAM CLIPPER SYSTEM WILL SWING THROUGH THE LOWER GREAT
LAKES LATE SUNDAY AND EARLY MONDAY AND WILL PRESENT CHANCES FOR
SNOW. AT THE SAME TIME...LOW PRESSURE ORGANIZING OVER THE LOWER
MISSISSIPPI VALLEY WILL TRACK NORTHEAST INTO THE LOWER APPALACHIANS
BY TUESDAY. ADDITIONALLY...OP GFS AND ECMWF BOTH TRACK ANOTHER
CLIPPER INTO THE MID MISSISSIPPI VALLEY. THE 00Z RUNS OF THE
OPERATIONAL MODELS ARE TRACKING THE MAIN SYSTEM EAST OF THE
APPALACHIANS AND ARE SUGGESTIVE OF LESS OF AN IMPACT TO THE REGION
WITH NO PHASING WITH THE CLIPPER TO THE NORTHWEST. GFS ENSEMBLE
MEMBERS ON THE OTHER HAND ARE ALL OVER THE PLACE WITH THE SURFACE
LOW TRACK DUE TO VARYING DEGREES OF PHASING IN THE UPPER LEVELS.
FURTHER MUDDYING THE WATERS IS THE MARGINAL TEMPS IN THE NEAR
SURFACE LAYER WHICH ARGUES FOR EVEN THE POSSIBILITY FOR OTHER PRECIP
TYPES TO MIX IN WITH SNOW FOR A TIME ON MONDAY AND TUESDAY.

THE UPPER LEVEL FLOW AND TELECONNECTION PATTERN SUGGESTS
POTENTIAL IS THERE FOR SOME SHIFT NORTH AND WEST TO THE MAIN
SYSTEM. WITH THE PRIMARY UPPER WAVE STILL OUT OVER THE PACIFIC AND
NOT FULLY SAMPLED YET...FUTURE MODEL RUNS TODAY AND SATURDAY WILL
BE CRITICAL IN DETERMINING IF THE MAIN STORM SHIFTS LEFT AND
PRESENTS A GREATER IMPACT TO PARTS OF THE FORECAST AREA FOR EARLY
WEEK. AT THIS TIME HOWEVER...ATTEMPTING TO EMPLOY ANY DETAIL
INCLUDING POTENTIAL SNOWFALL AMOUNTS IS POINTLESS. WILL CARRY
CHANCES OF SNOW MONDAY AND TUESDAY WITH A POSSIBILITY FOR RAIN TO
MIX IN ACROSS THE SOUTH TUESDAY AS CRITICAL LOW LEVEL THICKNESSES
WARM.

HIGH PRESSURE WILL BRING DRIER WEATHER TO THE REGION BY
MIDWEEK...WITH EXPANDING RIDGING ALOFT AND STRONG SOUTHERLY FLOW
PROVIDING A NICE WARMUP BY THE END OF THE WEEK AS TEMPERATURES GO
ABOVE NORMAL.

&&

.AVIATION /DISCUSSION FOR THE 120900Z TAF UPDATE/...
ISSUED AT 316 AM EST FRI FEB 12 2016

LITTLE CHANGE NEEDED FOR THE EARLY MORNING UPDATE. SEEING AREA OF SNOW
SHOWERS IMPACT CENTRAL ILLINOIS AS THEY MOVE SOUTHEAST. ANY
IMPACTS AGAIN LOOK PRIMARILY FOCUSED ON THE KBMG AND KHUF
TERMINALS THROUGH MID MORNING.

06Z DISCUSSION FOLLOWS.

UPPER DISTURBANCE CURRENTLY DROPPING SOUTHEAST THROUGH NORTHERN MISSOURI
IS EXPECTED TO SETTLE INTO WESTERN KENTUCKY AROUND SUNRISE FRIDAY. COULD
BE SOME LIGHT SNOW AT THE TERMINALS ROUGHLY 121000Z-121600Z ASSOCIATED WITH
THIS FEATURE...MAINLY IN THE KHUF/KBMG AREAS...BUT IT APPEARS ANY
IFR VISIBILITY RESTRICTIONS WILL REMAIN SOUTHWEST OF THE TERMINALS
CLOSER TO VORTICITY CENTER.

OTHERWISE...EXPECTING CEILINGS TO GRADUALLY LOWER OVERNIGHT AND INTO THE
MORNING HOURS ON FRIDAY...EVENTUALLY FALLING INTO THE MVFR CATEGORY TOWARDS
MIDDAY FRIDAY AS COLD ADVECTION DEVELOPS IN THE WAKE OF THE DISTURBANCE.

LIGHT SURFACE WINDS OVERNIGHT EXPECTED TO BECOME 260-280 DEGREES AT 10-13 KTS
BY MIDDAY FRIDAY.

&&

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

&&

$$TENTIAL

SYNOPSIS...JH
NEAR TERM...JH/NIELD
SHORT TERM...JH
LONG TERM....RYAN
AVIATION...JAS/RYAN



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