Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 231815
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
215 PM EDT THU APR 23 2015

.SYNOPSIS...
ISSUED AT 213 PM EDT THU APR 22 2015

A RIDGE OF HIGH PRESSURE EXTENDING FROM THE UPPER MIDWEST INTO THE
MID MISSISSIPPI RIVER VALLEY WILL OVERSPREAD THE GREAT LAKES INTO
THE OHIO VALLEY BY FRIDAY MORNING. AS THIS HIGH APPROACHES...WINDS
WILL DIMINISH EARLY THIS EVENING AND CLOUDS WILL DECREASE. QUIET
WEATHER WILL CONTINUE INTO FRIDAY BEFORE THE NEXT SYSTEM BRINGS
THE LIKELIHOOD OF RAIN ON SATURDAY. LOW TEMPERATURES TONIGHT WILL
DROP INTO THE UPPER 20S AND LOWER 30S. HIGH TEMPERATURES ON FRIDAY
WILL RANGE FROM 55 TO 60.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 431 AM EDT THU APR 23 2015

THE UPPER LEVEL TROF HAS MOVED EAST AND ALLOWED MUCH DRIER AIR TO
SPREAD INTO THE FORECAST AREA. ALSO...INCREASING SUBSIDENCE WILL
HELP KEEP SUNNY TO MOSTLY SUNNY SKIES TODAY. HOWEVER...CLOUDS MAY
LINGER OVER FAR NORTHWEST AREAS INCLUDING FAR SOUTHERN LOWER
MICHIGAN AND FAR NORTHERN NORTHWEST OHIO WHERE LOW LEVEL MOISTURE
SHOULD STILL BE SUFFICIENT COMBINED WITH LOW LEVEL MIXING TO PRODUCE
CLOUDS AT THE LIFTED CONDENSATION LEVEL. DAYTIME HEATING WILL ALLOW
MIXING DOWN OF HIGHER MOMENTUM AIR...ALTHOUGH WINDS TODAY SHOULD NOT
BE AS HIGH AS THEY WERE WEDNESDAY. WINDS SHOULD DECOUPLE TONIGHT AS
HIGH PRESSURE MOVES OVER THE AREA ALLOWING WINDS TO BECOME LIGHT.
OPTIMUM CONDITIONS TONIGHT SHOULD PREVAIL FOR VERY CHILLY LOWS.
CLEAR TO MOSTLY CLEAR SKIES...LIGHT WINDS AND A DRY AIRMASS SHOULD
ALLOW LOWS TO DROP TO AROUND 30 MOST AREAS...WITH TEMPERATURES
DROPPING TO BETWEEN 26 AND 30 DEGREES OVER NORTHEAST AREAS INCLUDING
NORTHWEST OHIO AND MUCH OF FAR SOUTHERN LOWER MICHIGAN. THESE COLDER
TEMPERATURES ARE REFLECTED ON THE LATEST GFS AND NAM GUIDANCE. HAVE
HELD OF WITH A FREEZE WARNING TONIGHT IN ORDER TO AVOID CONFUSION
DUE TO THE ONGOING FREEZE WARNING. WILL DEFER TO THE DAY SHIFT TO
ISSUE A NEW WARNING AFTER THE CURRENT WARNING EXPIRES.

&&

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 431 AM EDT THU APR 23 2015

RIDGING WILL MOVE SLOWLY EAST ACROSS THE GRTLKS FRIDAY PROVIDING
FAIR WX IN OUR AREA. WK LOW LEVEL WAA AND PLENTIFUL SUNSHINE AT
LEAST THROUGH EARLY AFTN SHOULD ALLOW HIGHS TO REACH THE M-U50S
AFTER A FROSTY START TO THE DAY.

LOW PRESSURE SYSTEM CURRENTLY OVER SRN CA IS EXPECTED TO MOVE EAST
ACROSS KS FRIDAY NIGHT. SHOWERS ALONG/NORTH OF THE WARM FRONT AHEAD
OF THIS SYSTEM SHOULD SPREAD ACROSS SWRN IL/IN OVERNIGHT...PSBLY
REACHING OUR AREA BY 12Z SATURDAY. INCRSG/THICKENING CLOUDINESS
FRIDAY NIGHT SHOULD LIMIT DIURNAL COOLING... BUT IF RAIN DOES MOVE
IN BY MORNING... TEMPS WILL PRBLY DROP OFF DUE TO EVAPORATIONAL
COOLING... STAYED CLOSE TO PREVIOUS FCST MINS RANGING FROM THE M30S
NE TO THE L40S SW.

KS LOW EXPECTED TO WEAKEN AS IT MOVES EAST SAT-SAT NGT BUT MODELS
TRENDING A LITTLE SLOWER SHEARING THE SYSTEM OUT... SO BUMPED UP
POPS SLIGHTLY DURING THE DAY SATURDAY... THOUGH STILL CONCERNED THAT
DRY LOW LEVEL EASTERLY FLOW WILL LIMIT OR PREVENT RAINFALL FROM OCRG
IN THE NE PORTION OF THE CWA. CLOUDINESS/RAIN SHOULD RESULT IN
COOLER TEMPS SATURDAY WITH HIGHS ONLY AROUND 50 AND A BRISK EASTERLY
WIND ADDING TO THE CHILL.

RIDGING EXPECTED TO SLOWLY BUILD EAST INTO THE GRTLKS EARLY NEXT
WEEK AS DEEP LOW OVER SERN CANADA REMAINS NRLY STNRY AND SLOWLY
WEAKENS. THIS SHOULD RESULT IN FAIR WX IN OUR AREA WITH N-NE LOW
LEVEL FLOW KEEPING TEMPS A BIT BLO NORMAL.

MEDIUM RANGE MODELS CONT TO HAVE CONSIDERABLE DIFFERENCES AND POOR
RUN-RUN CONTINUITY WRT LOW APCHG THE PAC NW TODAY. LATEST RUNS
SUGGEST THIS SYSTEM WILL DIG SE INTO W TX BY MONDAY AND THEN MOVE
EASTWARD TO THE LWR MS VALLEY OR SERN U.S. BY WED. WHILE THERE ARE
CONSIDERABLE DIFFERENCES IN STRENGTH/LOCATION OF THE LOW BY THAT
TIME... LATEST RUNS ARE IN GOOD AGREEMENT ON BULK OF PRECIP WITH
THIS SYSTEM REMAINING SOUTH OF OUR AREA. MAINTAINED A LOW CHC OF
SHOWERS FOR WED WITH TEMPS FCST NEAR NORMAL.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 202 PM EDT THU APR 23 2015

LOW LEVEL ANTICYCLONE TO OVERSPREAD THE REGION THROUGH FRIDAY
MORNING. DECOUPLING SHOULD OCCUR FAIRLY EARLY THIS EVENING.
CURRENT GUSTS TO AROUND 25 KNOTS SHOULD DIMINISH IN THE 22-23Z
TIMEFRAME...BEFORE WINDS BECOME LIGHT AND VARIABLE TOWARD 01Z.
MAINLY CLEAR SKIES ARE EXPECTED TONIGHT WITH SOME INCREASE IN MID
CLOUDS TOWARD THE END OF THE PERIOD AS MID LEVEL WARM ADVECTION
INCREASES. LIGHT AND VARIABLE WINDS SHOULD ALSO BECOME LIGHT
WESTERLY BY MID MORNING FRIDAY.

&&

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

$$

SYNOPSIS...MUPRHY/SKIPPER
SHORT TERM...SKIPPER
LONG TERM...JT
AVIATION...MARSILI


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