Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 212344
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
644 PM EST FRI NOV 21 2014

.SYNOPSIS...
ISSUED AT 400 PM EST FRI NOV 21 2014

SOUTHERLY WINDS WILL INCREASE INTO SATURDAY...DRAWING IN WARMER
AIR INTO THE REGION. RAIN WILL MOVE INTO THE AREA IN ADVANCE OF A
WEAK SYSTEM...STARTING AS A PERIOD OF LIGHT FREEZING RAIN BEFORE
TEMPERATURES QUICKLY RISE ABOVE FREEZING AFTER SUNRISE. LOW
TEMPERATURES TONIGHT WILL BE REACHED EARLY...PRIMARILY IN THE
UPPER TEENS TO LOWER 20S. HIGHS ON SATURDAY WILL PUSH WELL INTO
THE 40S.

&&

.UPDATE...
ISSUED AT 625 PM EST FRI NOV 21 2014

MINOR CHANGES ON EVE UPDATE TO PUSH BACK START OF MENTIONABLE POPS
UNTIL 06Z ACROSS THE ENTIRE AREA. SHOWERS DVLPG OVER MO WILL TAKE
AWHILE TO REACH OUR AREA AND MAY DIMINISH SOME AS THEY MOVE
THROUGH VERY DRY AIRMASS IN PLACE OVER IL/IN. A SHORT FREEZING
RAIN ADVISORY MAY BE NEEDED FOR EARLY SATURDAY MORNING BUT STILL
SOME UNCERTAINTY ON COVERAGE OF MEASURABLE PRECIP AND SFC TEMPS
IN OUR CWA IF AND WHEN PRECIP OCCURS... SO HELD OFF FOR NOW.

&&

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 407 PM EST FRI NOV 21 2014

TRANQUIL START TO THE SHORT TERM WILL QUICKLY END AS THE FIRST IN
A SERIES OF SYSTEMS MOVES INTO THE REGION AND RETURNS MORE
SEASONABLE TEMPERATURES AND INCREASING CHANCES FOR RAINFALL.

LEADING EDGE OF FIRST WAVE WAS ALREADY MOVING INTO MISSOURI AND WILL
ALLOW CLOUD COVER TO OVERSPREAD THE AREA THIS EVENING FROM SW TO NE.
ISENTROPIC LIFT WILL RAPIDLY INCREASE IN THE 6 TO 9Z SAT WINDOW
ALLOWING FOR LOWER LEVELS TO SATURATE AND LIGHT RAIN TO QUICKLY
DEVELOP ACROSS NW PARTS OF THE AREA...EVENTUALLY SPREADING EAST.
CONCERNS STILL LOOM FOR A BRIEF PERIOD OF FREEZING RAIN AT THE ONSET
AS STRONG WARM AIR ADVECTION OCCURS OVERTOP A SHALLOW COLD DOME IN
PLACE FROM THE RECENT COLD SNAP. BIG QUESTION WILL BE HOW FAST THIS
COLD DOME IS PUSHED OUT. MODELS HAVE GENERALLY TRENDED FASTER WITH
ARRIVAL OF WARMER SURFACE TEMPERATURES WITH ALL BUT NE SECTIONS
LIKELY ABOVE FREEZING BY 12Z SAT. A 2 TO MAYBE 4 HOUR WINDOW WILL
EXIST AT ANY ONE SPOT FOR SOME MINOR ICE ACCUMULATION AS THE COLD
GROUND WILL TAKE SOME TIME TO WARM...EVEN AS TEMPS CLIMB ABOVE
FREEZING. ONCE TEMPERATURES ARE IN THE 33 TO 34 DEGREE RANGE...ANY
ICE ACCRETION SHOULD END. HAVE INCREASED POPS ACROSS THE BOARD WITH
CAT POPS IN THE NW TO HIGH CHC IN SE WHERE DEEPER MSTR WILL TAKE A
BIT LONGER TO ARRIVE. WHILE ICE ACCUMULATIONS WILL BE AT MOST A FEW
HUNDREDTHS OF AN INCH...THIS MAY STILL BE ENOUGH TO CAUSE SOME SLICK
SPOTS. SINCE CONFIDENCE IN THE DURATION AND EXTENT OF ICING IS STILL
LOW...WILL FRESHEN UP THE SPS ISSUED BY THE PREVIOUS SHIFT. LOWS
WILL OCCUR THIS EVENING WITH SLOWLY RISING TEMPERATURES FROM THAT
POINT.

RAIN WILL CONTINUE THROUGH SATURDAY MORNING BEFORE DIMINISHING IN
COVERAGE INTO THE AFTERNOON HOURS AS PEAK LIFT SHIFTS NORTH OF THE
AREA. MAINTAIN CHC TO LIKELY POPS...HIGHEST NW. HIGHS WILL CLIMB
INTO THE LOW TO MID 40S WITH POTENTIAL FOR A FEW UPPER 40S IN SW
AREAS.

&&

.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 407 PM EST FRI NOV 21 2014

FEW CHANGES TO ONGOING FORECAST WITH PRIMARY FOCUS ON WEEKEND
RAINFALL AMOUNTS AND TIMING. FOCUS CONTS ON TWO
PRIMARY/HEIGHTENED RAFL EVENTS EMBEDDED WITHIN AN OTHERWISE
LIGHT/PROLONGED QPF EVENT. SHORTWAVE CURRENTLY IN NRN STREAM OVR
CNTL MT TIMED INTO UPR GRTLKS SAT NIGHT COINCIDENT WITH FIRST
MOISTURE SLUG PER 1000-850MB MSTR FLUX CONVERGENCE/6-7 G/KG
LIFTING NWD THROUGH CWA WITH PRIMARY FOCUS ON HIR LATE NIGHT
POPS/QPF. THEREAFTER...PSBL LULL/LIGHT FOR MUCH OF SUNDAY MORNING
WITH ONLY LIGHT AMOUNTS FORESEEN. SECOND ARDENT FOCUSED
LIFT/MOISTURE SURGE SUNDAY AFTN INTO SUNDAY NIGHT AS STRONG
VORTEX OVR GULF OF CAL DROPPING THROUGH EDWARDS PLATEAU THEN
LIFTING FROM NERN TX RAPIDLY NEWD INTO OHIO VALLEY LATE DY3.
PWATS RISE TO 1-1.1 INCHES APPROX 80TH PERCENTILE/ SUN EVE/ERLY
NIGHT AS EVEN GREATER BULK MOISTURE SURGE WITH 8 G/KG NOSING INTO
CNTL IN BY F66. FORCED PARCEL ASCENT ON NOSE OF 60-65 KT LOW
LEVEL JET COULD PORTEND TO ISOLD EMBEDDED TSRA...THOUGH WITH NAM
MUCAPE BLO 50 J/KG WILL OMIT FROM FCST ATTM. LESSENED DIURNAL
SWINGS PRIMARILY WITH WARMER LOW TEMPS THROUGH THE WEEKEND.
SLIGHTLY LATER TIMING OF CHANGEOVER RA/SN TO SN...PER CONSENSUS
AS ANTICIPATED WITH SYSTEM BECOMING INCRSNGLY NEGATIVELY TILTED.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 625 PM EST FRI NOV 21 2014

LOW LEVEL THETA-E ADVECTION COMBINED WITH A WK SHRTWV MOVG EAST
ACROSS THE AREA OVERNIGHT IS EXPECTED TO RESULT IN A PERIOD OF
FREEZING RAIN AT THE TERMINALS FROM 08Z-13Z. CONTD LOW LEVEL WAA
AND NEARLY SATURATED LOW LEVELS EXPECTED TO PERSIST IN WAKE OF
SHRTWV SATURDAY... CONTINUING TO CAUSE LOW CIGS AND OCNL -RA/BR AT
THE TERMINALS THROUGH THE DAY. CONTD FCST OF MVFR WITH LOWEST
CONDITIONS AT SBN WHERE SOME IFR PSBL... BUT HELD IN LOW MVFR
RANGE FOR NOW.

&&

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

&&

$$

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


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