Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 221456 CCA
AFDIWX

AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE NORTHERN INDIANA
955 AM EST SAT NOV 22 2014

.SYNOPSIS...
ISSUED AT 947 AM EST SAT NOV 22 2014

THE COMBINATION OF AN UPPER LEVEL DISTURBANCE AND WARMER AIR
MOVING BACK INTO THE REGION WILL RESULT IN INTERMITTENT RAIN
TODAY. RAIN WILL BECOME MORE WIDESPREAD TONIGHT WITH TEMPERATURES
STAYING WELL ABOVE FREEZING. HIGHS TODAY WILL CLIMB INTO THE MID
AND UPPER 40S. LOW TEMPERATURES TONIGHT WILL RANGE FROM 40 TO 45.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 342 AM EST SAT NOV 22 2014

A SHORT WINDOW OF FREEZING RAIN POTENTIAL EARLY THIS MORNING ALONG
WITH CONTINUED CHANCES OF RAIN THIS AFTERNOON/NIGHT WILL CONTINUE TO
BE THE PRIMARY SHORT TERM CHALLENGES.

KIWX VAD WIND PROFILE DEPICTS 45-50 KNOT SOUTHWESTERLY WINDS IN
THE 3-5K FT LAYER MARKING STRONG LOW LEVEL WARM/MOISTURE ADVECTION.
IN ADDITION TO BROAD ISENTROPIC FORCING...WATER VAPOR IMAGERY
INDICATES AN UPPER LEVEL SHORT WAVE CENTERED ACROSS NORTHERN
ILLINOIS/SOUTHERN WISCONSIN EARLY THIS MORNING. MOST WIDESPREAD
PRECIP AT 08Z PER REGIONAL RADAR MOSAIC EXTENDS FROM NEAR
MICHIGAN CITY INDIANA TO NORTH OF KOKOMO INDIANA...CORRELATING WELL
TO STRONGEST 900-800 HPA MOISTURE FLUX CONVERGENCE. PRECIP TYPES
WILL BE QUITE TRICKY THIS MORNING DUE TO COMPETING PROCESSES OF
EVAPORATIVE/WET BULB COOLING AND STRONG LOW LEVEL WAA. FOR THE MOST
PART...UPSTREAM LOCATIONS ACROSS ILLINOIS HAVE EXPERIENCED
RELATIVELY LIMITED KNOWN IMPACTS TO THIS POINT AS SFC TEMPERATURES
HAVE RISEN TO AT OR ABOVE FREEZING SHORTLY AFTER PRECIP ONSET.
HOWEVER...HAVE NOTED SOME COOLING CLOUD TOPS ACROSS NORTHEAST
ILLINOIS/NORTHWEST INDIANA OVER THE PAST COUPLE OF HOURS WITH PRECIP
A BIT MORE CONVECTIVE IN NATURE....WHICH POSES SOME CONCERN FOR A
BRIEF PERIOD OF BETTER PRECIP RATES BEFORE PROFILES BECOME
SUPPORTIVE OF MAINLY RAIN. HAVE GONE AHEAD AND ISSUED A FREEZING
RAIN ADVISORY FOR ALL OF THE FORECAST AREA THIS MORNING. WITH TIME
WINDOW STILL LOOKING NARROW FOR FREEZING PRECIP...HAVE CARRIED THE
ADVISORY THROUGH 12Z FOR MOST LOCATIONS...EXCEPT THE FAR NORTHEAST
WHERE HAVE GONE WITH A 14Z EXPIRATION.

BY LATE MORNING...AXIS OF DEEPER MOISTURE SHOULD BEGIN TO SHIFT
EAST/SOUTHEAST OF THE LOCAL AREA WITH CONTINUED BROAD ISENTROPIC
UPGLIDE. WITH DIFFICULTY IN LATCHING ONTO A CLEAR FORCING MECHANISM
THIS AFTERNOON OUTSIDE OF BROAD WARM ADVECTION AND LOSS OF DEEPER
MOISTURE...HAVE TRANSITIONED WEATHER GRIDS TO SCATTERED RAIN
SHOWERS. NAM CONTINUES TO DEPICT RELATIVELY STEEP 700-500 HPA LAPSE
RATES OF 7-8 DEG CELSIUS/KM THROUGH THE AFTERNOON
HOWEVER...PARTICULARLY ACROSS THE NORTHWEST TWO THIRDS OF THE AREA
IN CLOSER PROXIMITY TO LOW LEVEL THERMAL RIDGE AXIS...WHERE HAVE
MAINTAINED THE HIGHEST POPS. DIURNAL RANGES WILL BE LIMITED TODAY
DUE TO EXPANSIVE LOW CLOUD COVER ALTHOUGH STRENGTH OF WAA SHOULD
YIELD HIGHS IN THE MID 40S...TO POSSIBLY UPPER 40S ACROSS THE
SOUTHWEST.

FOR TONIGHT...A MID/UPPER LEVEL TROUGH TRACKING ACROSS THE
SOUTHERN/CENTRAL PLAINS WILL ALLOW FOR BACKING MID LEVEL WINDS AND
SURGE OF DEEPER MOISTURE BACK INTO THE OHIO VALLEY/SOUTHERN GREAT
LAKES WITH INCREASING CHANCES OF RAIN ONCE AGAIN. DID ADD SOME AREAS
OF FOG FOR LOCATIONS WHICH WILL BE EXPERIENCING MELTING SNOWCOVER
TODAY ACROSS EXTREME NORTHERN INDIANA/SOUTHERN LOWER MICHIGAN. LOWS
TONIGHT UNDER THE INFLUENCE OF CLOUDS/PRECIP SHOULD REMAIN AROUND
40/LOWER 40S.

&&

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 342 AM EST SAT NOV 22 2014

A NORTHERN STREAM TROUGH AMPLIFYING INTO THE CENTRAL US WILL HELP
FORCE A POTENT PV ANOMALY (PRESENTLY DIGGING INTO FAR NORTHERN
MEXICO) NORTHEAST THROUGH THE REGION LATER SUNDAY/SUNDAY NIGHT.
PHASING OF THESE FEATURES AND ASSOCIATED DEEP UVM/MOISTURE PLUME
WILL SUPPORT RAPID CYCLOGENESIS...WITH SFC REFLECTION TRACK MODELED
NNE TO SRN LAKE MI SUNDAY NIGHT AND POTENTIALLY SUB-980 MB INTO THE
NRN LAKES MONDAY. SURGE OF DEEPER MOISTURE CONVERGENCE (PWATS
EXCEEDING 1") AND DEEP ASCENT UNDER COUPLED JET STRUCTURE WILL
LIKELY BRING A SOLID 0.60-1.20" OF RAIN TO THE LOCAL AREA LATER
SUNDAY INTO SUNDAY NIGHT. PCPN COVERAGE/INTENSITY DIMINISHES ON
MONDAY...ESPECIALLY SOUTHERN/EASTERN ZONES AS MID LVL DRY SLOT
OVERSPREADS AND WELL PRONOUNCED DEFORMATION AXIS MOST LIKELY SETS UP
NW OF IWX CWA. IF THE STRONGER GFS/GEM SOLUTIONS VERIFY A WIND
ADVISORY MAY BE NEEDED (00Z GFS DEEPENS CYCLONE TO 966 MB NEAR SAULT
STE. MARIE BY 18Z MONDAY...HOPEFULLY OVERDONE). OTHERWISE...EXPECT
FALLING TEMPS IN WAKE OF THE TRAILING COLD FRONT.

COLD/MOIST CYCLONIC FLOW WITHIN DEEP LAYERED EASTERN CONUS TROUGH
AXIS WILL KEEP CLOUDS AND SPORADIC SNOW SHOWERS/FLURRIES AROUND
MONDAY NIGHT INTO TUESDAY...ESPECIALLY NORTHWEST ZONES WHERE SOME
LAKE ENHANCEMENT/LIGHT ACCUMS ARE EXPECTED. THE MID-LATE WEEK PERIOD
WILL BE CHARACTERIZED BY COLD NORTHWEST FLOW AND SEVERAL CHANCES FOR
LIGHT SNOW AS SHORTWAVE ENERGY DIVES DOWN THE BACKSIDE OF MEAN
EASTERN CONUS UPPER TROUGH AND INTERACTS WITH AN EXISTING NRN HIGH
PLAINS TO MID MS VALLEY BAROCLINIC ZONE.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 637 AM EST SAT NOV 22 2014

WIDESPREAD PRECIP ASSOCIATED WITH AN UPPER LEVEL SHORT WAVE
TRACKING ACROSS THE SOUTHERN GREAT LAKES REGION AND STRONG LOW
LEVEL MOISTURE TRANSPORT/CONVERGENCE WILL DIMINISH IN COVERAGE
OVER THE NEXT FEW HOURS. THREAT OF FREEZING RAIN IS BEGINNING TO
SHIFT NORTH AND EAST OF THE TERMINALS EARLY THIS MORNING.
GENERALLY MVFR CIGS AROUND 2K FT EXPECTED FOR TERMINALS...ALTHOUGH
DID INCLUDE TEMPO IFR CIGS AT KSBN THROUGH MID MORNING WHERE
GREATER COVERAGE OF SHOWERS WILL EXIST OVER NEXT FEW HOURS. BETTER
CHANCE OF CIGS BLO 2K FT THROUGH THE PERIOD WILL EXIST AT KSBN.
MID LEVEL LAPSE RATES WILL REMAIN QUITE STEEP TODAY AND WITH BROAD
ISENTROPIC LIFT CONTINUING WOULD EXPECT SCATTERED SHOWERS THROUGH
THE DAY...WITH RAIN INCREASING AGAIN TONIGHT AS NEXT MID LEVEL
TROUGH APPROACHES FROM THE PLAINS. HAVE ALSO MAINTAINED LLWS
MENTION THROUGH 00Z THIS EVENING FOR BOTH TERMINALS.


&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR LMZ043-046.

&&

$$

SYNOPSIS...SKIPPER
SHORT TERM...MARSILI
LONG TERM...STEINWEDEL
AVIATION...MARSILI


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