Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 161751
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
151 PM EDT THU OCT 16 2014

.SYNOPSIS...
ISSUED AT 1126 AM EDT THU OCT 16 2014

A MOSTLY DRY DAY IS IN STORE TODAY...WITH THE EXCEPTION OF A FEW
SPRINKLES OR ISOLATED SHOWERS IN AREAS TO THE EAST. AN
APPROACHING DISTURBANCE WILL KEEP SKIES MOSTLY CLOUDY
TODAY...WITH ONLY A FEW BREAKS IN THE CLOUDS OBSERVED ON VISIBLE
SATELLITE LATE THIS MORNING. EXPECT HIGH TEMPERATURES TO TOP OUT
IN THE LOW TO MID 60S THIS AFTERNOON.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 343 AM EDT THU OCT 16 2014

CLOSED UPPER LEVEL LOW WILL CONTINUE TO SLOWLY SHIFT NORTHEAST
OVER THE NEXT 24 HOURS...REACHING SOUTHERN ONTARIO THIS AFTERNOON
AND THEN NORTH OF LAKE HURON BY FRIDAY MORNING. PROXIMITY OF THIS
FEATURE...YET ANOTHER WEAK DISTURBANCE AND SOME LAKE INFLUENCE
WILL ALLOW FOR CLOUD COVER TO PERSIST INTO THE AFTERNOON WITH
POCKETS OF LIGHT SHOWERS OR DRIZZLE POSSIBLE...MAINLY EAST WHERE
DEEPEST MSTR WILL STILL EXIST. SLGT CHC TO CHC POPS WILL WORK WITH
OVERALL COVERAGE AND QPF POTENTIAL ON THE LOWER END (TRACE AMOUNTS
MAINLY WEST TO FEW HUNDREDTHS EAST). WILL CONTINUE THE DOWNWARD
TREND IN PRECIPITATION CHANCES THIS AFTERNOON WITH DRY CONDITIONS
FOR THE AREA TONIGHT AS INFLUENCE OF THE UPPER LOW WANES.

HAVE KEPT CLOUD COVER LINGERING A BIT LONGER IN THE WEST THROUGH
THIS EVENING WITH SEVERAL MODELS SOUNDINGS SHOWING CLOUDS HOLDING ON
A BIT LONGER. HIGHS TODAY WILL REMAIN ON THE COOLER SIDE COURTESY OF
THE CLOUD COVER WITH COOLEST READINGS WEST. LOWS TONIGHT WILL DROP
BACK TO AROUND 50.

&&

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 343 AM EDT THU OCT 16 2014

A SERIES OF WAVES IN NORTHWEST FLOW ALOFT WILL PROVIDE FOR
PERIODIC RAIN CHANCES IN THE WITH BELOW NORMAL TEMPERATURES POST-
FRIDAY.

OLD UPPER TROUGH ACROSS THE EASTERN GREAT LAKES WILL GRADUALLY
PHASE WITH ANOTHER UPPER LEVEL PV ANOMALY WORKING ACROSS THE
UPPER MS VALLEY EARLY FRIDAY. A CONSOLIDATED AREA OF LOW PRESSURE
WILL DEEPEN ACROSS EASTERN ONTARIO/QUEBEC AS THIS OCCURS...WITH
TRAILING COLD FRONT APPROACHING THE WESTERN GREAT LAKES REGION
EARLY FRIDAY. STRONG LOW LEVEL HEIGHT GRADIENT ASSOCIATED WITH
PHASING SYSTEM WILL RESULT IN STEADY EASTWARD PROGRESSION OF WEAK
LOW LEVEL THERMAL RIDGING INTO THE OHIO VALLEY/SOUTHERN GREAT
LAKES REGION ON FRIDAY...WHICH STILL SUPPORTS WARMEST MAX TEMPS
ACROSS EASTERN HALF OF THE AREA. ONSET OF LOW LEVEL CAA IN THE
AFTERNOON WILL SUPPORT STEEP LOW LEVEL LAPSE RATES AND GOOD
MIXING...WHICH SHOULD PROMOTE HIGHS FROM THE MID 60S
WEST/NORTHWEST...TO UPPER 60S OR AROUND 70 FAR SOUTHEAST. BULK OF
THE DAY SHOULD BE DRY ON FRIDAY WITH STRONGEST FORCING ASSOCIATED
WITH UPPER MS VALLEY PV ANOMALY NOT EXPECTED TO REACH THE WESTERN
GREAT LAKES UNTIL CLOSER TO 00Z. DESPITE THIS STRONG
FORCING...PRECIP COVERAGE SHOULD BE SOMEWHAT LIMITED LATE FRIDAY
AFTERNOON INTO EARLY FRIDAY EVENING WITH MARGINAL DEPTH OF ANY
NOTABLE MOISTURE...ALONG WITH LINGERING EFFECTS OF MID/UPPER
LEVEL DRY INTRUSION EARLIER IN THE DAY.

RAIN SHOWER CHANCES SHOULD GRADUALLY RAMP UP LATER FRIDAY EVENING
WITH STRONGER LOW LEVEL COLD ADVECTION OVERSPREADING THE SOUTHERN
GREAT LAKES...AND A SERIES OF SMALLER SCALE VORTS ROTATING
THROUGH THE REGION. MODEL GUIDANCE HAS BEEN FAIRLY CONSISTENT IN
DEPICTING COMPACT UPPER JET STREAK AND SECONDARY PV ANOMALY
DROPPING SOUTHWARD ACROSS WESTERN GREAT LAKES LATER FRIDAY
NIGHT/EARLY SATURDAY...WHICH SHOULD ALSO BE COINCIDENT WITH
DEEPER SATURATION. PRECIP COVERAGE TO ALSO BECOME ENHANCED BY
STEEP LAKE- INDUCED LOW LEVEL LAPSE RATES...ALTHOUGH DEPTH OF
THIS INSTABILITY SHOULD BE RELATIVELY SHALLOW. WHILE CONFIDENCE
IS INCREASING IN MOST LOCATIONS RECEIVING SOME MEASURABLE RAIN
OVER A 12 TO 18 HOUR PERIOD FOR NORTHWEST PORTIONS OF THE
AREA...WILL CAP POPS IN HIGH CHANCE CATEGORY AT THIS TIME WITH
STILL SOME UNCERTAINTY IN TIMING PERIODS OF STRONGER UPPER
FORCING AND RESOLUTION OF LAKE INDUCED INSTABILITY. PRECIP
CHANCES SHOULD TRANSITION TO MORE LAKE EFFECT/ENHANCED IN NATURE
ON SATURDAY AS SYNOPTIC FORCING GRADUALLY SHIFTS EAST OF THE
AREA. HAVE ALSO MAINTAINED TREND FROM PREVIOUS FORECAST IN LOWER
MAX TEMPS FOR SATURDAY WITH 850 HPA TEMPS DROPPING INTO THE 0
DEGREE TO -3 DEGREE CELSIUS RANGE...AND HIGHS STRUGGLING TO THE
50 DEGREE MARK FOR SOME LOCATIONS.

PASSAGE OF THIS SECONDARY VORT SATURDAY WILL BE FOLLOWED BY
STRONGER MID LEVEL SUBSIDENCE AND EASTWARD MIGRATION OF CENTRAL
CONUS LOW LEVEL ANTICYCLONE. THIS SHOULD SET UP A CHILLY
CONDITIONS FOR SATURDAY NIGHT...WITH LOWS DROPPING INTO THE
30S...AND WILL LIKELY EVENTUALLY NEED FROST AND/OR FREEZE
HEADLINES FOR THIS PERIOD. THE LULL IN PRECIP CHANCES WILL BE
SHORT LIVED HOWEVER AS NEXT PROGRESSIVE UPPER WAVE TOPS SOUTHWEST
CANADIAN RIDGE...AND DIGS ACROSS THE GREAT LAKES REGION. STILL
SOME QUESTION AS TO HOW FAR SOUTH THIS WAVE WILL DIG...BUT DECENT
RUN TO RUN CONTINUITY AND STRENGTH OF THIS WAVE COULD VERY WELL
LEAD TO UPWARD POP ADJUSTMENTS IN UPCOMING FORECASTS FOR LATE
SUNDAY NIGHT/MONDAY. REINFORCING LOW LEVEL THERMAL TROUGH WITH
THIS FEATURE WILL KEEP BELOW NORMAL TEMPS IN PLACE THROUGH THE END
OF THIS FORECAST PERIOD.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 144 PM EDT THU OCT 16 2014

SLOW SCOUR/LIFT OF LOW LEVEL MOISTURE IN ADVANCE OF UPSTREAM
RIDGELINE. ANTICIPATE A FEW MORE POCKETS OF MVFR CONDITION NEXT
FEW HOURS UNTIL PEAK HEATING BRINGS CIGS TO VFR CAT. ISSUE
TONIGHT APPEARS TO BE STRATUS REDEVELOPMENT POTENTIAL AMID AN
INCREASINGLY MIXED/MOIST LAYER...ELEVATED ABOVE DEVELOPING
SURFACE INVERSION. FOR NOW WILL INTRODUCE AS CIGS TO 1KFT
COMMENSURATE WITH LLWS AS WSWLY JET RAMPS LATE NIGHT/EARLY FRI
AM. LATER FORECAST ITERATIONS TO LIKELY DELVE MORE INTO STRATUS
CONFIDENCE/POTENTIAL FOR PROGRESSION DOWN INTO IFR CAT.

&&

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

$$

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


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