Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 291909
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
309 PM EDT WED JUL 29 2015

.SYNOPSIS...
ISSUED AT 308 PM EDT WED JUL 29 2015

A WEAK FRONT IS CURRENTLY PASSING THROUGH THE GREAT
LAKES AND WILL BRING A FEW SHOWERS AND THUNDERSTORMS TO THE
AREA THROUGH THE LATE AFTERNOON. COOLER AND DRIER CONDITIONS
EXPECTED OVERNIGHT AND INTO TOMORROW AS HIGH PRESSURE RETURNS TO
THE REGION. HIGHS TOMORROW WILL BE IN THE LOW TO MID 80S WITH MUCH
LOWER HUMIDITY LEVELS.

&&

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 308 PM EDT WED JUL 29 2015

WEAK COLD FRONT EXTENDING FROM VERTICALLY STACKED LOW PRESSURE
OVER NORTHERN ONTARIO IS CURRENTLY PUSHING THROUGH THE AREA. LOW
LEVEL CONVERGENCE IS BROAD AND DIFFUSE WITH THE BEST CVA/HEIGHT
FALLS WELL TO OUR NORTH. HOWEVER...STRONG DIABATIC HEATING...IN
CONCERT WITH SURFACE DEWPOINTS IN THE MID 70S HAS ALLOWED MODERATE
DESTABILIZATION WITH MLCAPE VALUES 1500-2000 J/KG ALONG AND EAST
OF I-69. BKN LINE OF THUNDERSTORMS HAS DEVELOPED AS A RESULT AND
WILL CONTINUE TO PUSH EASTWARD DURING THE LATE AFTERNOON. A FEW
STRONG STORMS WITH GUSTY WINDS POSSIBLE GIVEN DEGREE OF
INSTABILITY BUT VERY WEAK WIND/SHEAR PROFILES ALOFT HAVE...AND
WILL CONTINUE TO...LIMIT THE THREAT FOR ORGANIZED/SEVERE WEATHER.
INITIAL LINE IS EXITING OUR CWA AT PRESS TIME BUT DID LEAVE SOME
CHANCE POPS FURTHER WEST GIVEN DEWPOINT/INSTABILITY GRADIENT IS
JUST NOW ENTERING OUR WESTERN ZONES AND SEVERAL HI-RES MODELS SHOW
ADDITIONAL DEVELOPMENT POSSIBLE IN OUR CENTRAL AND EASTERN HALF
THROUGH THE LATE AFTERNOON. THIS IS ALSO SUPPORTED BY LATEST RADAR
MOSAIC WHICH SHOWS A FEW SHOWERS ALONG LAKE BREEZE BOUNDARY. DRY
CONDITIONS WILL RETURN EVERYWHERE BY TONIGHT THOUGH AND PERSIST
THROUGH TOMORROW AS HIGH PRESSURE AND MUCH DRIER AIR FILTER INTO
THE REGION. HIGHS TOMORROW WILL BE SLIGHTLY COOLER (LOW TO MID
80S) BUT IT WILL ALSO BE MUCH LESS HUMID WITH AFTERNOON DEWPOINTS
DROPPING INTO THE 50S. DEEP MIXING COULD ALLOW FOR SOME GUSTY
WINDS DURING THE AFTERNOON BUT NOTHING IMPACTFUL...20 TO 30 MPH AT
BEST.

&&

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 308 PM EDT WED JUL 29 2015

FORECAST PERIOD TO BEGIN WITH DEEP CLOSED UPPER LOW OVER THE
HUDSON BAY AND EXPANSIVE UPPER RIDGE OVER THE DESERT SW RESULTING
IN NW FLOW OVER THE GREAT LAKES AND MIDWEST. THIS WILL BRING A
SERIES OF WEAK DISTURBANCES THRU THE REGION AND IN THE ABSENCE OF
ANY LARGE SCALE FORCING WILL EVENTUALLY LAY OUT A QUASI-STATIONARY
BOUNDARY. THE FIRST OF THESE WILL DROP DOWN INTO NORTHERN LOWER
MICHIGAN FRIDAY NIGHT AND DRAG A WEAK BOUNDARY THROUGH OUR AREA
THAT WILL BE LIMITED IN MOISTURE...FORCING...AND INSTABILITY WHICH
WILL KEEP PRECIP CHANCES AT A MINIMUM. NEXT SYSTEM TO WORK ACROSS
THE GREAT LAKES ON SUNDAY DRAGGING ANOTHER WEAK SURFACE BOUNDARY
INTO THE AREA. MODELS HAVE THIS BOUNDARY STALLING OUT IN THE
MIDWEST/OHIO VALLEY WHICH HAS SUPERBLEND LITTERING THE REMAINDER
OF THE EXTENDED WITH SMALL CHANCE POPS. LATEST RUNS OF GFS AND
ECMWF INDICATING BEST TARGET OF OPPORTUNITY FOR ELIMINATING POPS
WILL BE TOWARD THE END OF THE FCST PERIOD AS BOTH MODELS HAVE WEAK
SURFACE RIDGING BUILDING INTO THE GREAT LAKES REGION TUESDAY NIGHT
INTO WEDNESDAY WHICH WOULD PUSH FRONTAL BOUNDARY FURTHER SOUTH TO
OH/TN VALLEY. WILL BACK POPS DOWN IN LINE WITH MOSGUIDE TO MINIMUM
SLIGHT CHANCE AND SEE IF SUBSEQUENT RUNS CONTINUE IN THIS
DIRECTION. SEASONABLE TEMPS THROUGH THE PERIOD WITH 80S/60S
RESPECTIVELY.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 122 PM EDT WED JUL 29 2015

WEAK COLD FRONT IS CURRENTLY PUSHING THROUGH THE AREA WITH A FEW
SHOWERS AND THUNDERSTORMS DEVELOPING AROUND KFWA. NO CHANCE FOR
THUNDER AT KSBN BUT SOME MVFR STRATOCU MAY BE POSSIBLE DURING THE
NEXT FEW HOURS UNTIL DRIER AIR CURRENTLY OVER CHICAGO IS ADVECTED
EASTWARD. VFR CONDITIONS EXPECTED OVERNIGHT AND TOMORROW WITH HIGH
PRESSURE AND MUCH DRIER AIR BUILDING INTO THE REGION.


&&

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

$$

SYNOPSIS...T/AGD
SHORT TERM...AGD
LONG TERM...JAL
AVIATION...AGD


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