Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 020006
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
806 PM EDT WED APR 1 2015

.SYNOPSIS...
ISSUED AT 354 PM EDT WED APR 1 2015

EXPECT PRIMARILY INCREASING CLOUDS INTO THE OVERNIGHT PERIOD AS
LOW PRESSURE APPROACHES THE REGION. LOWS OVERNIGHT WILL BE IN THE
40S AND LOW TO MID 50S. RAIN WILL MOVE IN EARLY THURSDAY MORNING
AND CONTINUE THROUGH THE DAY. SCATTERED THUNDERSTORMS ARE ALSO
EXPECTED...THOUGH THE RISK FOR SEVERE STORMS IS MARGINAL. HIGHS
THURSDAY WILL RANGE FROM 60 TO THE LOW 70S.

&&

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 348 PM EDT WED APR 1 2015

DRY WITH ONLY A GRADUAL INCREASE IN MID/HIGH CLOUDS EXPECTED THROUGH
THE EARLY OVERNIGHT AS MID LEVEL SHORTWAVE AXIS TRANSLATES THROUGH.
CLOUDS AND CHANCES FOR SHOWERS INCREASE LATER TONIGHT INTO EARLY
THURSDAY MORNING WITH LEADING EDGE OF DEEPER MOISTURE WITHIN
DEVELOPING LLJ RAMP...AND EXPECTATIONS FOR A MO/AR CONVECTIVELY
ENHANCED LEAD SHORTWAVE TO KICK NORTHEAST TOWARD THE LOWER LAKES.
COULD ALSO SEE A FEW RUMBLES OF THUNDER INTO THURSDAY MORNING WITH
GUIDANCE CONTINUING TO HINT AT SOME WEAK ELEVATED INSTABILITY.
LIMITING FACTOR FOR MORE WIDESPREAD SHOWERS/HEAVIER RAIN AT LEAST
INITIALLY WILL BE RESIDUAL DRY NEAR SURFACE AIR.

CONVECTIVE OUTFLOW BOUNDARY FROM UPPER MIDWEST CONVECTION AND
PRIMARY SYNOPTIC COLD FRONT WILL DROP SOUTHEAST INTO AN INCREASINGLY
MOIST ENVIRONMENT LATE THURSDAY MORNING/AFTERNOON. THIS COMBINED
WITH INCREASING/DEEPER INFLUENCE OF CYCLONIC FLOW AND MODEST 40-50M
5H HEIGHT FALLS TIED TO LARGER SCALE SHORTWAVE ENERGY WORKING INTO
THE NORTHERN LAKES/ONTARIO SHOULD PROVIDE A FAVORABLE ENVIRONMENT
FOR SHOWERS/STORMS. COULD SEE SOME LOCALLY HEAVY RAINFALL AS PWATS
PUSH 1.25 INCHES AND 850 MB DEWPOINTS 9-10C IN PRE-FRONTAL THETA-E
RIDGE. OTHERWISE...HIGH SHEAR (ESPECIALLY IN LOWEST 3 KFT) AND
POTENTIAL FOR A NARROW/WEAK CAPE PROFILE (MLCAPE MAY NEAR 500 J/KG
IF MODELED SFC DEWPOINTS REACH THE MID-UPPER 50S AND A FEW BREAKS
OCCUR IN OVERCAST/PCPN) WARRANT SPC`S MARGINAL SEVERE RISK ACROSS
SOUTHERN/EASTERN ZONES MID-LATE AFTN.

&&

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 348 PM EDT WED APR 1 2015

FRONTAL BOUNDARY WILL STALL JUST TO OUR SOUTH ON THURSDAY NIGHT WITH
A BRIEF BREAK FROM PRECIP FOR AT LEAST OUR NORTHERN HALF. STILL SOME
DISAGREEMENT AMONG LATEST NWP ON EXACTLY HOW FAR SOUTH THE LOW LEVEL
THETA-E TROUGH WILL PUSH. NAM12 IS THE RELATIVE OUTLIER IN KEEPING
PRECIP CHANCES AS FAR NORTH AS THE US30 CORRIDOR. PREFER A SLIGHTLY
MORE SOUTHWARD SOLUTION AND HAVE SCALED BACK POPS ACROSS THE NORTH
WHILE KEEPING CATEGORICAL IN THE FAR SOUTH. SECONDARY UPPER LEVEL
JET STREAK WILL THEN EJECT OUT OF THE SOUTHWEST CONUS AND COUPLE
WITH THE GREAT LAKES JET. VERY GOOD UPPER DIVERGENCE AND
PHASED/DEEPENING OF PV ANOMALY JUST UPSTREAM WILL FAVOR CYCLOGENESIS
ALONG STALLED FRONTAL BOUNDARY. A HEALTHY STRIPE OF
DEFORMATION-FORCED PRECIP WILL DEVELOP OVER OUR CWA DURING THE
LATTER HALF OF THE DAY FRIDAY AS A RESULT. AGAIN PREFER A BLEND OF
THE GFS/GEM/ECMWF SOLUTIONS WHICH SPREAD AT LEAST MEASURABLE PRECIP
OVER THE WHOLE AREA AND PERHAPS SOME DECENT QPF TOTALS OVER THE
SOUTH. SOME CONCERN FOR A RAIN/SNOW MIX ON THE NORTHERN FRINGES OF
PRECIP SHIELD...ESPECIALLY BY FRIDAY EVENING. HOWEVER...JUDGING BY
LATEST FORECAST SOUNDINGS AND THERMAL/MOISTURE PROFILES ACROSS THE
AREA...GUT FEELING IS THAT MOST AREAS WILL DRY OUT BEFORE BECOMING
COLD ENOUGH TO SUPPORT SNOW. MAINTAINED CHANCE RN/SN MIX BUT LITTLE
TO NO ACCUMULATION OR IMPACT EXPECTED.

COOL AND DRY CONDITIONS ANTICIPATED FOR SATURDAY AS HIGH
PRESSURE...AVA...AND NORTHWEST FLOW RETURN TO THE REGION. 850MB
TEMPS START OUT THE DAY AROUND -7C BUT DO RECOVER TO AROUND -2C BY
LATE AFTERNOON. AS A RESULT...OUR WESTERN ZONES COULD STILL TOUCH
THE LOWER 50S GIVEN AMPLE SUN AND DEEP MIXING. RAISED TEMPS ACROSS
THE BOARD BUT ESPECIALLY IN OUR WESTERN COUNTIES. TRANQUIL WEATHER
WILL BE SHORT-LIVED THOUGH. DETAILS STILL SKETCHY BUT APPEARS WE
GET BACK INTO AN ACTIVE PATTERN FOR AT LEAST THE FIRST HALF OF NEXT
WEEK. LARGE TROUGH IS SET TO DEVELOP OVER THE ROCKIES WITH
DOWNSTREAM RIDGING OVER THE EASTERN CONUS PLACING US IN DEEP
SOUTHWEST FLOW ALOFT. AMPLE THETA-E ADVECTION WITH EMBEDDED
SHORTWAVES WILL BRING PERIODIC CHANCES FOR PRECIP EVEN BEFORE THE
MAIN SURFACE LOW/OCCLUDED FRONT ARRIVE. LARGE DEGREE OF DIFFERENCE
BETWEEN THE ECMWF AND GFS REGARDING HOW THIS SYSTEM WILL EVOLVE SO
FOR NOW HAVE JUST MAINTAINED GENERALLY CHANCE POPS THROUGH MUCH OF
THE EXTENDED.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 747 PM EDT WED APR 1 2015

SOUTHERLY FLOW WILL INCREASE TONIGHT AS MID/UPPER LEVEL RIDGE AXIS
PROGRESSES ACROSS THE SOUTHERN GREAT LAKES. AN UPPER LEVEL
DISTURBANCE ACROSS MISSOURI THIS EVENING WILL SHIFT INTO THE OHIO
VALLEY BY THURSDAY MORNING. COMBINATION OF ISENTROPIC
LIFT/MOISTURE ADVECTION AND THIS FORCING SHOULD BE SUFFICIENT TO
GENERATE SCATTERED-NUMEROUS SHOWERS AFTER 12Z. ENOUGH ELEVATED
INSTABILITY MAY DEVELOP BY THE 13-16Z TIMEFRAME FOR SOME EMBEDDED
THUNDER. THIS LEAD WAVE WILL DEPART TO THE EAST BY MID TO LATE
MORNING WITH ATTENTION THEN TURNING TO NEXT SHORT WAVE TROUGH
APPROACHING THE WESTERN GREAT LAKES THURSDAY AFTERNOON.
COMBINATION OF THIS UPPER FORCING...ABUNDANT LOW/MID LEVEL
MOISTURE...AND LOW LEVEL FRONTAL FORCING SHOULD ALLOW FOR
WIDESPREAD RAIN SHOWERS AND EMBEDDED THUNDER THURSDAY
AFTERNOON...DIMINISHING TOWARD THE END OF THE PERIOD AS THE FRONT
SHIFTS EAST OF THE TERMINALS. HAVE MAINTAINED TREND TO MVFR
THURSDAY MORNING...WITH AT LEAST A PERIOD OF CIGS BELOW 2K FT
LIKELY DURING THE DAY. IN ADDITION...HAVE NOT INCLUDED ANY LLWS
FOR THE 00Z TAFS...BUT FUTURE AMENDMENTS/ISSUANCES MAY NEED TO
CONSIDER THIS WITH STRENGTHENING LOW LEVEL FLOW LATE TONIGHT.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 2 PM EDT THURSDAY FOR LMZ043-046.

&&

$$

SYNOPSIS...MCD
SHORT TERM...STEINWEDEL
LONG TERM...AGD
AVIATION...MARSILI


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