Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 010558
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
158 AM EDT TUE SEP 1 2015

.SYNOPSIS...
ISSUED AT 157 AM EDT TUE SEP 1 2015

PATCHY FOG WILL CONTINUE TO DEVELOP ACROSS THE AREA THIS
MORNING...BUT WILL BURN OFF SHORTLY AFTER SUNRISE. ISOLATED
SHOWERS AND THUNDERSTORMS ARE POSSIBLE FROM LATE MORNING INTO
TONIGHT AS AN UPPER LEVEL DISTURBANCE IS SLOW TO EXIT TO THE EAST.
WARM AND HUMID CONDITIONS ARE IN STORE TODAY...WITH HIGHS REACHING
INTO THE MID TO UPPER 80S.

&&

.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 349 PM EDT MON AUG 31 2015

SBCAPE 2000-2500 J/KG ALONG WITH MODEST 20-25 KT EFFECTIVE LAYER
SHEAR SUFFICIENT TO GENERATE ISOLD/SCT CONVECTION KMZZ INTO WEST
CENTRAL OHIO THIS AFTERNOON. FOCUS PRIMARILY ALONG LATENT/DIFFUSE
SFC BOUNDARY AND MODICUM OF DPVA FROM ORPHANED MID LEVEL VORTICITY
CENTER OVER CENTRAL INDIANA. WITH LACK OF SIG FORCING FEATURE/DEEP
LAYER SHEAR ANTICIPATE CONVECTION AGAIN TO BE LARGELY TIED TO
DIURNAL HEAT CYCLE/DISSIPATING TOWARD SUNSET. LOSS OF CU/WEAK
GRADIENT TO SET STAGE FOR DEVELOPMENT OF SHARP EARLY AM INVERSION
AND BR/FG POTENTIAL ONCE AGAIN LOOMS. DRIER RH CROSS SECTIONS LESS
SUGGESTIVE OF STRATUS AS SEEN PAST TWO DAYS. XOVER TEMPS ACRS CWA
IN UPR 60S SUGGEST AT LEAST PATCHY FOG TO DEVELOP. OPT FOR AREAS
OF FOG MENTION ACRS NWRN/NRN WHERE MARKEDLY SLOWER MIXING OBSERVED
TODAY. MIGRATION OF VORT MAX TO FAR WCNTL INDIANA BY
DAYBREAK...THEN FEATURE CATCHES INTO SOUTHERN PERIPHERY OF
NORTHERN STREAM AS NRN RIDGE OF REX IS WEAKENS. THIS FEATURE ALONG
WITH SIMILAR TO SLIGHTLY GREATER SFC BASED DESTABILIZATION POINT
TO LOW CHC POPS...ESPECIALLY TUE AFTERNOON.

&&

.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 349 PM EDT MON AUG 31 2015

TEMPERATURES IN THE MID-UPPER 80S STILL LOOK TO BE ON TRACK WED
INTO THE WEEKEND. THE FORECAST AREA WILL BE BENEATH AN UPPER LEVEL
RIDGE STARTING WEDNESDAY NIGHT AND CONTINUING INTO SUNDAY. NEXT
BEST CHANCE FOR PRECIPITATION APPEARS TO BE SUNDAY NIGHT/MONDAY
WHEN WE HAVE AN UPPER LEVEL LOW OVER THE NORTHERN PLAINS...AND AN
APPROACHING COLD FRONT TO OUR WEST. OTHERWISE...WE DEAL WITH THESE
PESKY WEAKER SHORT WAVES RIDING THE RIDGE THAT THREATEN TO FIRE
OFF SOME SHOWERS/STORMS EACH AFTERNOON. GIVEN UNCERTAINTY AND THE
SUBTLENESS OF THE PASSING WAVES...OPTED TO ADD SLIGHT CHANCE POPS
WED-FRI...BUT LIMITED IT TO MAINLY THE AFTERNOON HOURS AS THAT
WILL BE WHEN MOST INSTABILITY IS AVAILABLE. MODELS HAVE TRENDED
SLIGHTLY STRONGER WITH THE WAVE TUE/WED...AND EVEN SUGGEST THERE
COULD BE SOME SHOWERS/STORMS TUE NIGHT/WED AM. BUT GIVEN THE LOWER
CONFIDENCE KEPT THINGS DRY FOR THIS TIME PERIOD...WITH THE
EXCEPTION OF SLIGHT CHANCE POPS IN THE SOUTH EARLY TUESDAY
EVENING.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 157 AM EDT TUE SEP 1 2015

NEAR TERM CONCERN WILL CONTINUE TO BE POTENTIAL FOG DEVELOPMENT
IMPACTING TERMINALS THROUGH EARLY THIS MORNING. ANOTHER NIGHT OF
IDEAL RADIATIONAL COOLING CONDITIONS HAS ALLOWED FOR A FEW
LOCATIONS ACROSS NORTHERN INDIANA/SOUTHERN LOWER MICHIGAN TO DROP
TO IFR/LIFR VSBYS AS OF 0530Z. STILL SOME LOW CONFIDENCE IN TERMS
OF IFR/LIFR CONDITIONS AT TERMINALS...WITH LATEST AMDAR DATA STILL
SUGGESTING SOME MODEST LOW LEVEL FLOW RAISING SIMILAR QUESTIONS
AS LAST NIGHT IN TERMS OF FOG VS STRATUS. GROUND CONDITIONS DID
DRY OUT SOMEWHAT YESTERDAY WITH BETTER INSOLATION/SFC HEATING
WHICH MAY ALSO PLAY SOME ROLE IN LIMITING EXTENT OF FOG AS
COMPARISON TO YESTERDAY. AT THIS TIME WILL MAINTAIN TEMPO IFR
VSBYS AT BOTH TERMINALS IN THE 09Z-12Z TIMEFRAME...BUT CERTAINLY
NOT OUT OF THE REALM OF POSSIBILITY FOR SOME LIFR VSBYS DURING
THIS TIMEFRAME PARTICULARLY AT KSBN.

OTHERWISE...DEPARTING UPPER VORT MAX ACROSS NORTHEAST INDIANA MAY
TRIGGER ISOLATED SHOWERS/STORMS LATE MORNING/AFTERNOON WITH SOME
INDICATIONS THAT EVEN KSBN COULD BE SUSCEPTIBLE TO ISOLATED
SHOWERS AS A CORRIDOR OF WARM ADVECTION SETS UP IN THE WAKE OF
THIS VORT MAX. POINT PROBABILITIES ARE TOO LOW FOR PRECIP MENTION
AT THIS TIME HOWEVER AND WILL CARRY DRY/VFR FORECAST AFTER THIS
MORNINGS FOG ERODES AFTER 12Z.

&&

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

$$

SYNOPSIS...MARSILI
SHORT TERM...MURPHY
LONG TERM...MCD
AVIATION...MARSILI


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