Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 050538
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
1238 AM EST THU MAR 5 2015

.SYNOPSIS...
ISSUED AT 355 PM EST WED MAR 4 2015

SIGNIFICANT WEATHER IS EXPECTED TONIGHT INTO THURSDAY NEAR AND SOUTH
OF THE OHIO RIVER AS HEAVY SNOW IS EXPECTED WITH OVER 6 INCHES OF
ACCUMULATION POSSIBLE. TRAVEL MAY BE DIFFICULT IN THIS REGION.
ELSEWHERE AROUND THE REGION IT WILL BE MOSTLY CLOUDY AND COLD. LOW
TEMPERATURES TONIGHT WILL DROP TO BELOW ZERO ACROSS MICHIGAN AND
INTO THE SINGLE DIGITS ABOVE ZERO CENTRAL AND SOUTH. TEMPERATURES ON
THURSDAY WILL BE VERY COLD FOR EARLY MARCH. HIGHS WILL BE IN THE
MIDDLE TO UPPER TEENS.

&&

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 351 PM EST WED MAR 4 2015

ROBUST DEEP LATITUDINAL POSITIVE TILTED LONGWAVE TROF SUPPORTING
EXTREME BAROCLINICITY FM NERN TX TO TN VALLEY. TROF TO REMAIN
POSITIVE TILTED AND PROGRESSIVE WITH POTENT UPSTREAM KICKERS
FIRST ACRS NRN ALBERTA AND ADDITIONAL SHORTWAVE TOPPING RIDGE
AXIS INTO FAR NWRN BC. SUPPRESSION OF SRN STREAM TO MAINTAIN
PRIMARY SENSIBLE WX EFFECTS WELL TO SOUTH OF RGN.
OTHERWISE...ANTICIPATE NOMINAL LAKE RESPONSE AS LK/8H
DIFFERENTIALS REACH TO NEAR 20C BY 06 UTC AMID 320-325 DEGREE
FETCH. LOW EQL SHOULD PRECLUDE ALL BUT SCT FLURRIES/NON
MEASURABLE OVERNIGHT. SLIGHT POP/MSRBL MENTION ON THU WITH
SLIGHTLY HIR DIFFERENTIALS AND PEAK LK INDUCED CAPES TO 350 J/KG.
CLOUD COVERAGE...ESPECIALLY MID LEVEL STREAM PERSISTING SPCLY
SRN/SERN CWA PER WV IMAGERY...AFFORDS DIFFICULT MIN TEMP FCST
WITH BUST POTNL SKEWED STRONGLY TO WARM SIDE SHOULD BRKS FAIL TO
DVLP. BOTTOM TROF/INFLECTION OF ARCTIC AIRMASS EXPECTED THU/THU
NIGHT COINCIDENT WITH LOW LEVEL THERMAL TROF AXIS ACRS CWA.

&&

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 351 PM EST WED MAR 4 2015

MODIFICATION OF AIRMASS BEGINS ON FRIDAY AS UPPER LEVEL PATTERN
FLATTENS ACROSS NORTHERN NORTH AMERICA. EASTERN NAM TROF CONTINUES
TO SHIFT EAST AS THE UPPER LEVEL PATTERN BECOMES LESS AMPLIFIED
OVER THE LOWER 48. COLD AIR WILL BE PUSHED DEEPER INTO WESTERN NAM
WITH REAMPLIFICATION OF THE TROF ALONG THE DATELINE.

THIS SETS THE STAGE FOR A PRONOUNCED WARMUP BEGINNING DURING THE
LATTER PART OF THE COMING WEEKEND INTO EARLY NEXT WEEK.
TEMPERATURES WILL BE SOMEWHAT COOLER THAN MODELS...AS THE SNOW
MELTS.

INCREASED SUN ANGLE AND LESS SNOW COVER WILL ALLOW TEMPERATURES
TO REALLY BEING TO CLIMB MONDAY NIGHT THROUGH THE END OF THE
FORECAST PERIOD.

FORTUNATELY...NO RAIN AND GRADUAL MELTING WILL KEEP FLOODING TO A
MINIMUM. LIKELY TO SEE SOME ICE FLOW/JAM FORMATION BY LATE
WEEKEND INTO EARLY NEXT WEEK.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1227 AM EST THU MAR 5 2015

SLIGHT VEERING OF LOW LEVEL FLOW EXPECTED TONIGHT WITH WIND SPEEDS
REMAINING AT OR BELOW 10 KNOTS. CONTINUED LOW LEVEL COLD ADVECTION
AND APPROACHING POSITIVELY TILTED SHORT WAVE SYNOPTIC CONTRIBUTION
MAY YIELD SOME WEAK LAKE RESPONSE IN THE 10Z-16Z TIMEFRAME. VERY
DRY AIR ABOVE THE LOW LEVEL INVERSION SHOULD LIMIT THIS RESPONSE
HOWEVER...AND HAVE LIMITED MENTION TO HIGHER END MVFR CIGS AROUND
3K FT DURING THIS PERIOD. WINDS TO BECOME MORE WESTERLY ON
THURSDAY...AND THEN EVENTUALLY LIGHT SOUTHWEST TOWARD THE END OF
THE PERIOD AS SURFACE ANTICYCLONE BEINGS TO SHIFT ACROSS THE OHIO
RIVER VALLEY.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&

$$

SYNOPSIS...LASHLEY
SHORT TERM...MURPHY
LONG TERM...LEWIS
AVIATION...MARSILI


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