FXUS63 KIWX 050632
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
132 AM EST SUN FEB 5 2012

.AVIATION...
CLOUDS WERE CLEARING FROM NORTH TO SOUTH...ALLOWING GROUND FOG TO
FORM WHERE SKIES HAD CLEARED. HAVE ADJUSTED TIMING OF FOG IN THE
TAFS ACCORDING TO CONDITIONAL CLIMATOLOGY. WENT LOWER WITH VSBYS
AT FWA WHERE NEARLY HALF AN INCH OF RAIN/MELTED SNOW HAD FALLEN
YESTERDAY. ANY GROUND FOG WILL MIX OUT AFTER SUNRISE.
OTHERWISE...A SFC RIDGE WILL REMAIN OVER THE AREA WITH LIGHT
NORTHWEST TO NORTH FLOW.

&&

.PREV DISCUSSION... /ISSUED 347 PM EST SAT FEB 4 2012/

SHORT TERM.../TONIGHT THROUGH SUNDAY NIGHT/

SHOWERS IN AREA OF PERSISTENT MID LEVEL FGEN FORCING AHEAD OF MO LOW
WERE MOVG INTO SWRN PORTION OF CWA THIS AFTN. DRIER AIR ADVECTING
INTO THE AREA FROM THE N-NE EVIDENT IN DISSIPATING LOW CLOUDS OVER
MI AND EARLIER DISSIPATING SHOWERS ACROSS SERN ZONES. THIS LOW LEVEL
DRY AIR ADVECTION SHOULD CONTINUE THIS EVE AND MID LEVEL FGEN
FORCING/DEEPER MOISTURE MOVE S-SE AS A SHRTWV DROPS ACROSS THE
GRTLKS. THUS... TAPERED OFF HIGH POPS OVER S-SWRN ZONES LATE THIS
AFTN TO JUST A CHC OF RAIN/SNOW THIS EVE. CLEARING EXPECTED TO
WORK SOUTH ACROSS THE CWA OVERNIGHT. WITH MOIST BOUNDARY LAYER
CONDITIONS IN PLACE FROM SGFNT PRECIP EVENT EARLIER TODAY AND
WK GRADIENT OVERNIGHT... BOUNDARY LAYER SHOULD DECOUPLE AND SOME
FOG DEVELOP BY MORNING. WITH GOOD RADIATIONAL COOLING CONDITIONS
EXPECTED OVERNIGHT... FCST MINS AT OR A BIT BLO LOWEST MOS.

RIDGE WILL MOVE ACROSS THE AREA SUNDAY AFTN/EVE. SKIES SHOULD BE
MOSTLY SUNNY SUNDAY BUT WK FLOW WILL LIMIT MIXING...ESPECIALLY IN
AREAS WITH LINGERING SNOW COVER ACROSS CENTRAL PORTION OF CWA.
STAYED CLOSE TO PREVIOUS FCST HIGHS GENERALLY IN THE L40S. MOSTLY
CLEAR SKIES SHOULD CONT SUNDAY NIGHT. LIGHT WINDS ASSOCIATED WITH
THE RIDGE PASSAGE WILL AGAIN ALLOW FOR GOOD RADIATIONAL
COOLING...THOUGH GRADIENT WILL STRENGTHEN LATE AS A CDFNT DROPS
INTO THE UPR GRTLKS. LEANED TOWARD COOLER MAV MINS ESPECIALLY OVER
CENTRAL PORTION OF CWA WHERE SOME SNOW COVER LIKELY WILL PERSIST.

LONG TERM.../MONDAY THROUGH SATURDAY/

WHAT LIMITED CONFIDENCE EXISTS IN THE MODELS LIES IN THE FIRST FEW
DAYS AS MODELS CONTINUE TO POINT TOWARDS MONDAY BEING A FAIRLY
DECENT DAY AHEAD OF A COLD FRONT SET TO MOVE THROUGH LATE MONDAY
NIGHT INTO TUESDAY. HIGHS MONDAY SHOULD CLIMB INTO THE MIDDLE 40S
WITH LOWS MONDAY NIGHT BACK INTO THE UPPER 20S TO AROUND 30. ENERGY
LEFT OVER IN THE PLAINS FROM THE CURRENT UPPER LEVEL SYSTEM WILL BE
PICKED UP BY THE TROUGH ASSOCIATED WITH THE COLD FRONT. THIS MAY
SLOW THE OVERALL PROGRESS OF THE FRONT AND ALSO AS THE TROUGH DROPS
IN...REMAINING PIECE OF ENERGY WILL BEGIN TO EJECT TOWARDS THE
REGION. DEPENDING ON MODEL OF CHOICE THE GFS WEAKENS THIS WAVE WITH
LITTLE OVERALL EFFECT ON THE SYSTEM RESULTING IN A QUICK PUSH
THROUGH OF THE FRONT. THE ECMWF BRINGS THE FRONT INTO THE UPPER OHIO
VALLEY AND WOULD APPEAR TO STALL IT OUT SOMEWHAT AS PLAINS ENERGY
EJECTS AND BRINGS A CHANCE FOR SOME LIGHT SNOW WEDS INTO WEDS EVE.
WILL CONTINUE SLGT CHC POP MENTION WITH UNCERTAINTY REMAINING ON THE
HANDLING OF THIS FEATURE.

THE LARGER FOCUS...AND LARGER AREA OF DISAGREEMENT...CONTINUES TO
RESIDE WITH POLAR HIGH AND ITS EFFECTS ON THE REGION INTO THE
WEEKEND. 12Z ECMWF AND GEFS HAVE COME INTO AT LEAST SOME AGREEMENT
ON COLDER SOLUTION VS OPERATIONAL GFS. THAT BEING SAID ECMWF STILL
THE COLDEST WITH 850 MB TEMPS DROPPING INTO THE -16 TO -19 CELSIUS
RANGE. SPAGHETTI PLOTS FOR ENSEMBLE SHOWS THE MASS DISARRAY IN TEMP
SOLUTIONS WITH OVERALL MEAN ENDING UP AROUND -15 CELSIUS. WITH
OVERALL DOWNWARD TREND IN TEMPS STILL HINTED AT...WILL FOLLOW CR
ALLBLEND GRIDS TO HEAD TO BELOW NORMAL LEVELS BY FRI AND SAT. STILL
APPEARS TO BE A GLANCING BLOW FOR THE COLD WEATHER WITH MODERATING
TEMPS INTO THE START OF THE NEXT WORK WEEK. AS FOR PRECIP...GFS MOST
ROBUST WITH POPS THURS WITH LINGERING LAKE EFFECT THURS NGT INTO
SAT. ECMWF BRINGS IN SOME LIGHT PRECIP LATE THURS NGT INTO FRI. HAVE
WENT WITH POPS IN THE FRI THROUGH SAT TIME FRAME ACROSS THE NORTH
WHERE BEST POTENTIAL LOOKS TO LIE FOR NOW. NO REAL DETAIL ADDED FOR
LAKE EFFECT AS THIS WOULD BE PREMATURE IN DAY 7 PERIOD WITH LACK OF
MODEL RESOLUTION AND CONCERNS FOR DEPTH AND PLACEMENT OF COLD AIR
STILL EXISTING.

&&

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

$$

SHORT TERM...JT
LONG TERM...FISHER
AVIATION...SKIPPER


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