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000
FXUS63 KIWX 200026
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
826 PM EDT SUN MAY 19 2013

.SYNOPSIS...
ISSUED AT 504 PM EDT SUN MAY 19 2013

SKIES WILL REMAIN MOSTLY CLEAR TO PARTLY CLOUDY TONIGHT...WITH LOW
TEMPERATURES MAINLY IN THE MID 60S. A LOW PRESSURE SYSTEM WILL MAKE
ITS WAY ACROSS THE REGION EARLY THIS WEEK...BRINGING CHANCES FOR
SHOWERS AND THUNDERSTORMS THROUGHOUT THE WEEK. TEMPERATURES ARE
EXPECTED TO BE FAIRLY WARM MONDAY AND TUESDAY BEFORE DROPPING DOWN
TO MORE SEASONABLE LEVELS BY THE END OF THE WEEK.

&&

.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 320 PM EDT SUN MAY 19 2013

TIGHT DEWPOINT GRADIENT WHICH HAD BEEN EVER PERSISTENT ACROSS OUR
AREA HAS FINALLY BEEN ERRADICATED AS LOW TO MID 60S DEWPOINTS HAVE
NOW OVERSPREAD THE ENTIRE CWA. THIS INCREASE IN SURFACE DEWPOINTS
HAS YIELDED SBCAPE VALUES BETWEEN 1500 AND 2000 J/KG. WITH A LACK OF
ANY SIGNIFICANT FORCING...NOTHING MORE THAN A SCATTERED TO BROKEN CU
DECK HAS BEEN ABLE TO DEVELOP.  THIS CU FIELD WILL DISSIPATE BY
LATE AFTERNOON AS A DEEP EML/CAPPING INVERSION OVERSPREADS THE CWA
FROM THE WEST.

PRECIP POTENTIAL FOR TONIGHT REMAINS COMPLICATED AS SIGNIFICANT
MODEL SPREAD EXISTS REGARDING THE LOCATION AND PERSISTENCE OF
REMNANT CONVECTION FROM IOWA/MISSOURI SEVERE WEATHER TODAY. GLOBAL
MODELS KEEP CONVECTION NORTHWEST OF OUR CWA...WHILE HI
RESOLUTION/CONVECTION ALLOWING MODELS BRING PRECIP INTO AT LEAST THE
WESTERN HALF OF THE CWA AFTER 05Z BEFORE COMPLETELY DISSIPATING.
KEPT SLIGHT CHANCE POPS IN THE NORTHWEST OVERNIGHT WITH THE ONLY
CHANGE BEING A SLIGHTLY EARLIER ARRIVAL TIME AS HRRR GUIDANCE IS
CONSISTENTLY BRINGING CONVECTION INTO WESTERN AREAS BETWEEN 03-04Z.

TEMPS WILL WARM INTO THE UPPER 80S ON MONDAY WITH A FEW LOCATIONS
LIKELY REACHING 90 DEGREES. THESE ABOVE NORMAL TEMPS COUPLED WITH
UPPER 60S TO NEAR 70 DEWPOINTS WILL MAKE THE MONDAY AIRMASS QUITE
UNSTABLE. KEPT POPS IN THE LOW CHANCE RANGE AS UNCERTAINTIES
REGARDING THE STRENGTH OF THE CAP AND ANY CONVECTIVE DEBRIS WHICH
MAY OVERSPREAD THE AREA LIMIT CONFIDENCE. IF CONVECTION CAN
DEVELOP...SEVERE POTENTIAL WILL INCREASE THROUGH TIME AS A 50-60 KT
MID-LEVEL JET STREAK CLIPS THE NORTHWEST PORTION OF OUR FORECAST
AREA NEAR 21Z AND IMPROVES THE SHEAR PROFILE.

&&

.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 320 PM EDT SUN MAY 19 2013

FCST PERIOD TO BEGIN WITH SFC LOW AND VERTICALLY STACKED CLOSED
UPPER LOW OVER THE NORTHERN PLAINS/UPPER MIDWEST. BEST FOCUS AND
FORCING FOR CONVECTIVE INITIATION HEADING INTO MONDAY EVENING WILL
BE TO THE WEST OF OUR AREA DESPITE BEING IN A VERY UNSTABLE WARM
SECTOR WITH CAPES AOA 3000J/KG OVER MUCH OF THE CWA. 500MB RIDGE
SHIFTS EAST OF THE AREA MON NITE AND BREAKDOWN OF THICKNESS RIDGE
WILL PROVIDE AN OPPORTUNITY FOR CONVECTION TO WORK INTO THE WESTERN
CWA 06-12Z TUE. GOOD MOISTURE ADVECTION ON A 40-50KT LLJ ALONG WITH
A 50-60KT MID LEVEL SPEED MAX WILL ACCOMPANY SFC PRE-FRONTAL TROF ON
TUE BRINGING GOOD CONVECTIVE POTENTIAL INTO THE AREA. UNCERTAINTY
WILL BE IN ABILITY FOR DESTABILIZATION...PUTTING SEVERE POTENTIAL IN
QUESTION. MAIN SFC FRONT TO FOLLOW ON WED WHICH WILL KEEP LIKELY
POPS FOR SH/TSRA GOING DURING THE DAY. SECONDARY FRONT THEN SET TO
MOVE THRU ON THURSDAY BEFORE ENTIRE SYSTEM FINALLY KICKS EAST OF OUR
AREA AND SETS THE STAGE FOR A COOLER BUT PLEASANT START TO THE
MEMORIAL DAY WEEKEND AS CANADIAN HIGH PRESSURE BUILDS INTO THE GREAT
LAKES REGION ON FRI/SAT. GFS AND ECMWF TRENDING TOWARD A MUCH
DIFFERENT SOLN COMPARED TO EARLIER RUNS FOR THE REST OF THE HOLIDAY
WEEKEND. WHAT WAS ONCE AN AMPLIFIED NW FLOW PATTERN WITH A
RE-ENFORCING DRY CANADIAN AIRMASS IS NOW BEING OFFERED AS A
TRANSITION TO A MORE ZONAL PATTERN AND KICKING SHORTWAVE DISTURBANCE
INTO THE REGION AND A CHANCE FOR PRECIP SUNDAY. NOT EAGER TO BUY
INTO THIS SOLN JUST YET...ESPECIALLY GIVEN THAT EVEN THE HIGHER END
OF THE ENSEMBLE MEMBERS HAVE POPS BELOW CLIMO. THAT AND GIVEN ITS IN
DAY 7 WILL OPT TO CONTINUE WITH DRY FCST FOR NOW AND WAIT TO SEE IF
TREND CONTINUES AND STRONGER SIGNAL IN MODEL GUIDANCE PRESENTS
ITSELF.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 825 PM EDT SUN MAY 19 2013

VFR MET CONDITIONS CONTINUE ODDS ON FAVORITE THROUGH THE FORECAST
PERIOD. INTENSE CONVECTIVE UPSTREAM TIED TO PLAINS DRYLINE/PVU
ANOMALY PUNCHING THROUGH EASTERN KS. WITH NORTHERN INDIANA WELL
REMOVED FROM BELT OF STRONGEST SOUTHWESTERLIES AND SECURELY CAPPED
AT THIS TIME...THE PRIME FOCUS AREA FOR COLLOCATED INSTABILITY AND
FORCED ASCENT WILL REMAIN WELL SOUTHWEST-WEST-NORTHWEST OF
NORTHERN INDIANA TERMINAL SITES. A GRADUAL UPTICK IN CONDITIONAL
PROBABILITIES FOR TSRA SEEN LATE IN FORECAST PERIOD...ESPECIALLY
INTO NORTHWEST INDIANA/KSBN VCNTY AS UPPER LOW COALESCES ACROSS
ND/SD/MN BORDER REGION BY 00 UTC TUE. STILL...CONVECTION MORE
LIKELY THAN NOT TO REMAIN UPSTREAM. WITH INITIATION FOCUSED ALONG
WARM FRONT EXTENSION ACROSS WISCONSIN...AND A SECONDARY AREA WELL
TO THE SOUTHWEST...WITHIN MAXIMUM LATE AFTERNOON DESTABILIZATION
ACROSS WEST CENTRAL ILLINOIS SOUTHWEST INTO OZARKS.

&&

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

$$

SYNOPSIS...KG
SHORT TERM...BENTLEY
LONG TERM...JAL
AVIATION...MURPHY


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