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000
FXUS63 KIWX 191144 CCA
AFDIWX

AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE NORTHERN INDIANA
541 AM EST THU DEC 19 2013

.SYNOPSIS...
ISSUED AT 417 AM EST THU DEC 19 2013

A SERIES OF LOW PRESSURE SYSTEMS WILL BRING WET CONDITIONS TO THE
REGION INTO THE WEEKEND. THE FIRST ONE WILL ARRIVE LATER TODAY
INTO FRIDAY WITH LIGHT RAIN AND WARMER TEMPERATURES. THE
NEXT...STRONGER SYSTEM WILL ARRIVE FOR THE WEEKEND...POSSIBLY
STARTING AS A BRIEF PERIOD OF FREEZING RAIN BEFORE
STEADY...LOCALLY HEAVY RAIN MOVES IN. HIGH TEMPERATURES TODAY WILL
BE IN THE UPPER 30S TO LOWER 40S WITH LOWS DROPPING INTO THE MID
TO UPPER 30S IN THE EVENING BEFORE CLIMBING OVERNIGHT.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 417 AM EST THU DEC 19 2013

STRONG 925 MB JET ON THE ORDER OF 45 TO 55 KNOTS HAS BEEN EXTREMELY
EFFICIENT ON USHERING IN WAA THIS EVENING WITH TEMPERATURES ACROSS
THE AREA CLIMBING A DEGREE OR 2 EACH HOUR. APPEARS UPWARD TREND MAY
BE SLOWING A BIT AS FLOW BEGINS TO SUBSIDE SOMEWHAT BUT STILL
EXPECTING MANY LOCATIONS TO BE IN THE MID TO UPPER 30S DESPITE
SEVERAL INCHES OF SNOWPACK. THE SLOWLY MELTING SNOW HAS CONTRIBUTED
SOMEWHAT TO A SLOW INCREASE IN DEWPTS BUT MORE SUBSTANTIAL INCREASE
IN LOW LEVEL MSTR REMAINED BACK ACROSS ILLINOIS. MANY OF THE HI RES
MODELS ARE STRUGGLING TO HANDLE THE SPEED OF THE WARMER AIR WITH THE
ARW APPEARING TO BE THE ONLY ONE EVEN CLOSE. A CONTINUED 30 TO 40 KT
LLJ WILL ALLOW DEWPTS TO CLIMB INTO THE LOW TO MID 30S INTO THE
DAYLIGHT HOURS OF THURSDAY. WHILE THE LAYER OF MSTR WILL BE RATHER
SHALLOW...THIS COMBINED WITH THE MELTING SNOW WILL LIKELY LEAD TO A
THICK LAYER OF STRATUS AND AREAS OF FOG AND DRIZZLE AS WEAK
ISENTROPIC LIFT BEGINS TO ARRIVE ACROSS THE AREA. CONDENSATION
PRESSURE DEFICITS (CPD`S) DON`T DECREASE MUCH UNTIL AFTER 18Z AND
REALLY TAKE TILL 00Z FRI TO MAKE ANY APPRECIABLE PROGRESS. HAVE
OPTED TO BACK OFF ONSET OF MEASURABLE PRECIP SOMEWHAT AND CONFINE TO
FAR NW INITIALLY WITH EXPANSION S/E WITH TIME. HAVE INCREASED POPS
TONIGHT...ESPECIALLY LATE EVENING INTO THE OVERNIGHT HOURS WHEN
SECONDARY SURGE OF LL MSTR AND LIFT ARRIVES AND CPD`S BOTTOM OUT.
HAVE WENT WITH A PERIOD OF CATEGORICAL POPS FOR THE ENTIRE CWA BY 9Z
AND THEN STARTED A SLOW TAPER IN THE NW TO LIKELY THROUGH 12Z.

LOWS TONIGHT WILL OCCUR EARLY WITH SOME INITIAL DROP FROM COOLING AS
SATURATION OCCURS THICKER CLOUD COVER ARRIVES. HOWEVER...ONCE
UNDERWAY...SFC LOW APPROACHING THE AREA WILL INITIATE THE SECONDARY
SURGE OF WARMER AIR WITH RISING TEMPS OVERNIGHT...POSSIBLY WELL INTO
THE 40S.

&&

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 417 AM EST THU DEC 19 2013

GULF MOISTURE WILL FLOW N-NE IN ADVANCE OF A SLOW MOVG CDFNT WHICH
WILL BE CROSSING OUR AREA FRIDAY MORNING. FAIRLY DEEP LOW-MID LEVEL
SATURATION...WARM LAYER ALOFT... AND DRY DGZ SUGGESTS ANY PRECIP
DURING THE DAY WILL BE LIQUID. TO VARYING DEGREES MODELS ALL SUGGEST
A WK WAVE WILL MOVE ALONG THE FRONT AND THROUGH OUR CWA DURING THE
DAY ENHANCING LOW LEVEL CONVERGENCE AND LEADING TO SOME RAIN. CAA NW
OF THE FRONT WILL LEAD TO SLOWLY FALLING TEMPS IN THE 30S NW PORTION
OF THE CWA WHILE SE RISES INTO THE M40S. AS THE WAVE MOVES OFF TO
THE NE FRI NGT... CDFNT EXPECTED TO CONT SETTLING SLOWLY SE-S. WK
SUBSIDENCE SHOULD OVERSPREAD THE AREA DURING THIS PERIOD AS CDFNT
MOVES SE-S OF THE CWA AND MID LEVEL SHRTWV DEPARTS THE REGION. STILL
THERE WILL BE PLENTIFUL LOW LEVEL MOISTURE LINGERING OVER THE AREA
SO THERE REMAINS A GOOD CHC OF LINGERING LIGHT RAIN OR DRIZZLE
ESPECIALLY SE EARLY IN THE NIGHT. WK CAA BEHIND THE FRONT SHOULD
ALLOW TEMPS TO FALL INTO THE L30S NW WHICH SUGGESTS SOME LIGHT
FREEZING RAIN OR FREEZING DRIZZLE PSBL OVERNIGHT... BUT GIVEN LOW
POPS AND MARGINAL TEMPS... THREAT OF HAZARDOUS CONDITIONS FOR THIS
PERIOD SEEMS RATHER LOW ATTM.

STRONG LOW PRESSURE SYSTEM DIGGING INTO SRN CA THIS MORNING IS
EXPECTED TO LIFT NE FROM THE SRN PLAINS SATURDAY AND MOVE ACROSS THE
GRTLKS SUNDAY. STRONG FORCING AND A VERY MOIST AIRMASS OVERSPREADING
THE AREA SHOULD RESULT IN HEAVY RAINFALL ACROSS OUR AREA AS THE
SYSTEM MOVES THROUGH. SREF QPF INDICATES 1-3" WITH HEAVIEST AMOUNTS
OVER SE PORTION OF CWA SATURDAY NIGHT. COMBINATION OF THE HEAVY
RAINFALL... SNOWMELT... AND FROZEN GROUND SHOULD RESULT IN SOME
FLOODING OF RIVERS/CREEKS IN THE AREA BY SUNDAY WITH SGFNT FLOODING
PSBL... ESPECIALLY OVER SERN PORTIONS OF THE CWA. WHILE BULK OF
PRECIP EXPECTED TO BE LIQUID IN OUR AREA... A CHANGEOVER TO SNOW
SHOULD OCCUR FROM NW-SE SUNDAY AS CAA ON BACKSIDE OF THE LOW
OVERSPREADS THE AREA. NW PORTION OF THE CWA COULD HAVE SOME
ACCUMULATION AS IT GETS INTO DEFORMATION ZONE WITH TEMPS COLD ENOUGH
FOR SNOW. THE RAPID COOL DOWN BEHIND THIS SYSTEM WILL FREEZE SOME OF
THE RUN-OFF FROM THE WEEKENDS HEAVY RAINFALL BY MONDAY... PSBLY
LIMITING RISES ON AREA RIVERS.

NW FLOW WILL BRING BLO NORMAL TEMPS AND PRBLY SCT LAKE EFFECT SNOW
SHOWERS BACK TO THE AREA EARLY NEXT WEEK. SFC RIDGE EXPECTED TO MOVE
ACROSS THE AREA TUE BRINGING THE LAKE EFFECT TO AN END WITH A CHC OF
SNOW MOVG INTO THE AREA ON WED AS ANOTHER CDFNT MOVES ACROSS THE WRN
GRTLKS.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 532 AM EST THU DEC 19 2013

LLWS THREAT HAS SUBSIDED ENOUGH TO REMOVE FROM TAFS BUT STRONG
WINDS REMAIN JUST ABOVE THE SURFACE AND WILL PERSIST MUCH OF THE
DAY. HINTS AT A NEED FOR LLWS ONCE AGAIN EXIST LATER TONIGHT
MAINLY AT KFWA. HAVE OPTED TO HOLD OFF ANY MENTION FOR NOW.

ALSO PUSHED BACK ONSET OF STRATUS/FOG TO A BIT LATER THIS MORNING
AS ONLY LIMITED INDICATION OF DEVELOPMENT WITH TEMP/DEWPT SPREADS
IN MANY AREAS STILL 7 DEGREES OR MORE. TIMING OF ONSET OF STEADY
RAIN PUSHED BACK A FEW HOURS AS WELL DURING PEAK SATURATION AND
LIFT WITH LIFR CONDITIONS EXPECTED.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 10 AM EST THIS MORNING FOR LMZ043.

&&

$$

SYNOPSIS...FISHER
SHORT TERM...FISHER
LONG TERM...JT
AVIATION...FISHER


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