River Flood Warning 136, NWS Northern Indiana

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
418 PM EST WED DEC 14 2011

.SHORT TERM...
TONIGHT THROUGH THURSDAY NIGHT...
KIWX RADAR DEPICTING BAND OF MOD/HVY RAIN ALONG/AHEAD OF WARM FRONT
LIFTING NORTH THROUGH THE AREA THIS AFTERNOON. THIS IS IN
ASSOCIATION WITH DEVELOPING SFC LOW IN CENTRAL PLAINS. WATER VAPOR
IMAGERY AND LATEST RUC ANALYSIS SHOWING LEAD SHORT WAVE EJECTING OUT
OF FOUR CORNERS AND WILL COMBINE WITH COUPLED JET STRUCTURE FROM
NORTHERN GREAT LAKES DOWN INTO THE CENTRAL PLAINS TO DEEPEN SFC LOW
AND DRIVE IT INTO WESTERN GREAT LAKES THIS EVENING. THIS WILL
PLACE THE FCST AREA IN ENHANCED MOIST SOUTHERLY FLOW IN THE WARM
SECTOR AND SUPPORT ANOTHER ROUND OF PRECIPITATION TONIGHT. COLD
FRONT WILL MOVE THROUGH THE AREA ON THURSDAY AND BRING AN END TO
RAIN BY 18Z. SIGNIFICANT DRYING BEHIND THE FRONT ALONG WITH MARGINAL
DELTA T WILL PROVIDE LITTLE SUPPORT FOR LES IN THE WAKE OF THIS
SYSTEM SO FAVOR CURRENT GRIDS IN KEEPING JUST A MENTION OF FLURRIES
ATTM. FIRST TWO PERIODS OF FCST WILL FEATURE NON-DIURNAL TEMP
PATTERN AS WARM FRONT LIFTING NORTH OF THE AREA TONIGHT WILL KEEP
TEMPS STEADY/SLOWLY RISING...THEN CAA BEHIND PASSAGE OF COLD FRONT
THURSDAY WILL SEE HIGHS REACHED IN THE MORNING FOLLOWED BY FALLING
TEMPS IN THE AFTERNOON. COOLER BUT SEASONABLE TEMPS THURSDAY NIGHT
WITH LOWS IN THE MID-UPPER 20S.

&&

.LONG TERM...

FRIDAY THROUGH WEDNESDAY

ACTIVE NORTHERN STREAM WILL INFLUENCE LOWER HEIGHTS INTO THE REGION
THIS WEEKEND WITH COLDER/DRIER AIR PUSHING INTO THE GREAT LAKES...AS
PERIPHERY DISTURBANCES ADVECT THROUGH THE FLOW. A SERIES OF THESE
WEAK INFLUENCES MAY INFLUENCE ENOUGH LIFT AND COLUMN SATURATION TO
SUPPORT LIGHT SNOW OR FLURRIES ACROSS THE NORTH...ALONG WITH A WEAK
LAKE RESPONSE. OTHERWISE...MODELS AND ENSEMBLES CONTINUE TO SUPPORT
THE EJECTION OF A SW CONUS DISTURBANCE INTO THE REGION BY EARLY NEXT
WEEK...WITH SOME RATHER SIG DISCREPANCIES AMONG DETERMINISTIC
SOLUTIONS. WILL STAY THE COURSE WITH PERSISTENCE...FAVORING THE
WARMER ECMWF AND GEM. THIS WILL ESP BE TRUE IF FLOW PHASING IS
REALIZED...WHICH IS CERTAINLY POSSIBLE GIVEN THE PATTERN. SMALL
ADJUSTMENT MADE TO THE PREVIOUS FORECAST...GENERALLY TO POPS/WX.

FRI-SUN...OVERALL DRY/SLIGHTLY DISTURBED FLOW WILL REMAIN IN THE
GREAT LAKES REGION. CONTINUED TO OPT NOT TO INCLUDE A LAKE EFFECT
SNOW SHOWER MENTION FRI-SAT FAR NW GIVEN MARGINAL SUPPORT FOR LAKE
INDUCE CONVECTION...WITH ONLY A FLURRY MENTION ATTM...SPREAD OVER
THE ENTIRE NORTH TO COVER THE POTENTIAL FOR LIGHT SNOW WITH ANY OF
THE WEAK DISTURBANCES. PROFILES INDICATE SIG DRYING IN THE SFC TO H8
LAYER WITH MARGINAL DELTA T/S PRESENT. CANNOT RULE OUT A FEW
FLURRIES OR LIGHT LAKE EFFECT SNOW SHOWERS IF COLDER PROFILES
VERIFY...COUPLED WITH A WEAK NORTHERN STREAM DISTURBANCE PROGGED
INTO THE REGION...WHICH COULD GENERATE ENOUGH INVERSION HEIGHT
UNDULATION TO SUPPORT PERHAPS A FEW SNOW SHOWERS/FLURRIES IN SHORT
FETCH WESTERLY FLOW. OTHERWISE...TEMPS ARE EXPECTED TO REMAIN AROUND
NORMAL TO SLIGHTLY ABOVE IN THE PERIOD...WITH LAKE EFFECT CLOUDS
ACROSS NORTHERN AREAS LINGERING THROUGH SAT.

MON-WED...CHANCES FOR A DECENT STORM SYSTEM CONTINUE...AS AN ACTIVE
NORTHERN STREAM IMPULSE LIKELY INTERACTS WITH ANOTHER SW CONUS
UPPER LOW. ADVECTION TIMING/THERMAL FIELDS/AND HEIGHT FALL DEPTH
INTO THE REGION IS STILL MUCH UNCERTAIN...BUT GIVEN THE GFS/S
TENDENCY TOWARD PROGRESSIVE FLOW...LIKELY BIASING THE NAEFS
SOLUTIONS...HAVE CONTINUED TO SIDE TOWARD THE MORE RELIABLE ECMWF. A
TREND TO A DEEPER H5 SOLUTION WOULD CERTAINLY BE NEEDED...ESP IF
WAVE PHASING RESULTS...WITH COUPLED JET DYNAMICS LIKELY SHIFTING THE
SFC LOW TRACK NW OF THE FA...AS SEEN IN THE GEM. RETAINED A
RAIN/SNOW MENTION IN MOST PERIODS...MAINLY TO COVER
UNCERTAINTY...BUT IT CERTAINLY LOOKS LIKE RAIN WILL BE THE DOMINATE
WEATHER TYPE IN THE PERIOD...ESP SE HALF. CONTINUE TO EXPECT MORE
ADJUSTMENT IN THIS PERIOD.

&&

.AVIATION.../18Z TAFS/
KIWX RADAR INDICATING BAND OF MODERATE TO HEAVY RAIN IMPACTING KSBN
ATTM AND IS EXPECTED TO ARRIVE AT KFWA BETWEEN 19-20Z THIS AFTERNOON
KEEPING IFR CONDITIONS OVER THE AREA THROUGH MUCH OF THE TAF PERIOD.
LOW PRESSURE WILL TRACK UP INTO THE WESTERN GREAT LAKES THIS EVENING
KEEPING GUSTY S/SW FLOW AND LLWS AT BOTH TAF SITES INTO THE EARLY
MORNING HOURS THURSDAY. COLD FRONT WILL MOVE THROUGH THURSDAY
MORNING AND BRING AN END TO THE RAIN BUT LOW LEVEL MOISTURE WILL
KEEP IFR/MFVR CIGS OVER THE AREA THROUGH THE END OF THE TAF PERIOD.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...GALE WATCH THROUGH THURSDAY EVENING FOR LMZ043-046.

     SMALL CRAFT ADVISORY UNTIL 7 PM EST THIS EVENING FOR LMZ043-046.

&&

SHORT TERM...LOGSDON
LONG TERM...JC
AVIATION...LOGSDON