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327
FXUS63 KIWX 191751
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
151 PM EDT FRI SEP 19 2014

.SYNOPSIS...
ISSUED AT 355 AM EDT FRI SEP 19 2014

HIGH PRESSURE WILL BEGIN TO RETREAT EASTWARD IN ADVANCE OF A
DEVELOPING LOW PRESSURE SYSTEM ACROSS THE NORTHERN PLAINS. DRY
CONDITIONS WILL PERSIST INTO SATURDAY AFTERNOON WITH MODERATING
TEMPERATURES EXPECTED. HIGHS THIS AFTERNOON WILL REACH INTO THE LOW TO
MID 70S.

&&

.UPDATE...
ISSUED AT 145 PM EDT FRI SEP 19 2014

BROAD LOW LEVEL ANTICYCLONE WILL PROVIDE SUNNY/MOSTLY SUNNY SKIES
THROUGH THE REMAINDER OF THE AFTERNOON WITH JUST SOME LOW COVERAGE
CIRRUS WORKING ACROSS THE AREA. NAM SHORT TERM SOUNDINGS INDICATE
MIXING UP TO 900-875 HPA THIS AFTERNOON...WHICH WOULD SUPPORT
GOING HIGHS IN THE LOWER TO MID 70S. ALL OTHER FORECAST ELEMENTS
ARE IN GOOD SHAPE AND NO FIRST PERIOD ZFP UPDATE IS CURRENTLY
ANTICIPATED.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 355 AM EDT FRI SEP 19 2014

SFC RIDGE CNTRD OVR SERN ONTARIO WILL GIVE WAY TO PROGRESSIVE SW
TROUGH AND ATTENDANT FNTL SYS BY SAT. INCREASING LL WAA ESP LATE
THIS AFTN WILL GIVE A BOOST TO TEMPS ESP WRN/SRN ZONES VS YDA. MUCH
WARMER ESP WRN HALF IN PROXIMITY TO STGR SWRLY GRADIENT FLW AND
LIKELY ENCROACHMENT OF HIGH CLD SHIELD. OTRWS DRY AS WRN BOUND OF LL
ANTICYCLONE SLW TO MOISTEN ALG W/VEERED LL WRLY FLW SUGGESTING
GENERAL WK SUBSIDENT FLW WILL PERSIST INTO SAT AM.

&&

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 355 AM EDT FRI SEP 19 2014

POTENTIALLY ACTIVE SAT AFTN/EVE PERIOD IN STORE FOR AT LEAST NW
PARTS OF THE AREA AS INCREASINGLY FAVORABLE LOOKING DYNAMICS APPEAR
TO BE COMING INTO PLAY.

TOUGH FORECAST IN TERMS OF HOW TO HANDLE CHANCES FOR SHOWERS/STORMS
AS MODELS HAVE ALL BACKED OFF ON PRECIP CHANCES (NOW GENERALLY CHC
TO A FEW SPOTS SHOWING LIKELY) SAT AFTN/EVE AS SPEED AND DEPTH OF
MSTR RETURN REMAINS IN QUESTION. WITH LOW TO MID 60 DEWPTS NOT THAT
FAR AWAY GIVEN INCREASING FLOW WHICH WILL SETUP OVER THE NEXT 24
HOURS...IT IS PLAUSIBLE FOR SIMILAR VALUES TO ADVECT IN RIGHT AHEAD
OF THE COLD FRONT DURING PEAK HEATING. 0-3 KM SHEAR ON BUFKIT
SOUNDINGS ALL POINT TOWARDS ANYWHERE FROM 40 TO 50 KTS OF MAINLY
UNIDIRECTIONAL SHEAR. THIS WOULD SET THE STAGE FOR A RISK OF
STG-SEVERE STORMS IF TIMING AND MSTR ALIGN JUST RIGHT. MODELS VARY
GREATLY ON THESE POINTS RANGING FROM A FEW HUNDRED J/KG OF SURFACE
BASED CAPE TO PUSHING 2000 J/KG. SPC DAY 2 OUTLOOK HAS PLACED THE NW
QUARTER OR SO OF THE AREA IN A SLIGHT RISK FOR DAMAGING WINDS. WHILE
WE CAN`T DISAGREE...THIS WILL BE HIGHLY CONDITIONAL ON TEMPS
CLIMBING INTO THE UPPER 70S TO LOWER 80S AND DEWPTS INTO AT LEAST
THE LOWER 60S. RISK DIMINISHES RAPIDLY WITH SE PROGRESSION ASSUMING
NO ORGANIZED COLD POOL WERE TO ESTABLISH. CHANCES SAT AM LOOKING
RATHER POOR (IF THIS DID UNFOLD THEN CHANCE FOR SEVERE WOULD BE
DIMINISHED GIVEN POSSIBLE CONVECTIVE DEBRIS). HAVE CONFINED SLGT CHC
POPS TO FAR NW. OTHERWISE HAVE LEFT SAT AFTN INTO SAT NIGHT ALONE
DESPITE ABOVE MENTIONED ISSUES WITH GUIDANCE.

SOME LINGERING SHOWERS MAY EXIST IN THE SE SUNDAY MORNING...BUT
SHOULD QUICKLY DEPART WITH SEASONABLE AFTERNOON HIGHS IN THE LOWER
TO MIDDLE 70S. MAIN SHOT OF COLDER AIR WILL ARRIVE SUNDAY NIGHT WITH
SFC HIGH PRESSURE SETTLING OVER THE LOWER GREAT LAKES INTO NEXT
WEEK. COULD BE A STRAY SHOWER WITH THE TROUGH PASSAGE BUT OVERALL
LIFT AND REMAINING MSTR LOOKS RATHER BLEAK.

TEMPERATURES WILL BEGIN TO MODERATE BACK TOWARDS NORMAL LEVELS BY
MID WEEK AS THE HIGH SHIFTS EAST OF THE AREA AND THEN SETTLES IN
OVER THE EASTERN STATES. THIS SHOULD ALLOW FOR A QUIET
PERIOD...LIKELY EXTENDING INTO THE WEEKEND.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 145 PM EDT FRI SEP 19 2014

VFR CONDITIONS ARE EXPECTED THROUGH THE BULK OF THIS FORECAST
PERIOD. LARGE LOW LEVEL ANTICYCLONE ACROSS EASTERN CONUS WILL
CONTINUE TO BE THE PRIMARY FEATURE CONTROLLING WEATHER ACROSS
NORTHERN INDIANA THROUGH TONIGHT. SOUTHEAST WINDS ON THE WESTERN
PERIPHERY OF THIS HIGH PRESSURE WILL CONTINUE THROUGH THE
PERIOD...VEERING MORE SOUTHERLY TONIGHT AS NEXT TROUGH OF LOW
PRESSURE TRACKS INTO THE UPPER MIDWEST. STRONG LOW LEVEL THETAE
ADVECTION PRECEDING COLD FRONT IN ASSOCIATION WITH NEXT MID/UPPER
LEVEL SYSTEM WILL WORK ACROSS NORTHERN INDIANA SATURDAY MORNING.
SOME SHOWERS MAY DEVELOP IN ASSOCIATION WITH THIS STRONG LOW LEVEL
THETAE ADVECTION...BUT GREATER CHANCES OF SHOWERS AND
THUNDERSTORMS ARE EXPECTED TO HOLD OFF UNTIL AFTER 18Z AS
MID/UPPER LEVEL TROUGH AXIS APPROACHES WESTERN GREAT LAKES REGION.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...SMALL CRAFT ADVISORY FROM 11 PM THIS EVENING TO 5 PM EDT
     SATURDAY FOR LMZ043-046.

&&

$$

UPDATE...MARSILI
SYNOPSIS...T
SHORT TERM...T
LONG TERM...FISHER
AVIATION...MARSILI


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