Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 240800
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
400 AM EDT THU APR 24 2014

.SYNOPSIS...
ISSUED AT 400 AM EDT THU APR 24 2014

A FEW SPRINKLES ARE POSSIBLE ACROSS NORTHWEST INDIANA AND
SOUTHWEST MICHIGAN THIS MORNING AS A WEAK WARM FRONT LIFTS ACROSS
THE AREA. WARM AND DRY CONDITIONS ARE EXPECTED BEHIND THIS FRONT
TODAY WITH HIGH TEMPERATURES IN THE MID TO UPPER 60S. A LOW
PRESSURE SYSTEM WILL THEN BRING RAIN TO THE AREA LATER TONIGHT AND
INTO TOMORROW MORNING. LOWS TONIGHT WILL ONLY BE IN THE UPPER 40S
TO LOWER 50S.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 400 AM EDT THU APR 24 2014

SPRINKLES ASSOCIATED WITH WEAK BAND OF 295K ISENTROPIC ASCENT
CONTINUE TO STRUGGLE IN THE FACE OF VERY DRY/STABLE LOW LEVEL
ENVIRONMENT. HAVE SEEN A FEW RAIN REPORTS IN OUR WESTERN COUNTIES
THOUGH AND WILL MENTION A CHANCE OF SPRINKLES THROUGH THE EARLY
MORNING FOR OUR WEST/NORTHWEST ZONES. WARM FRONTAL FEATURE WILL LIFT
NORTH BY LATER THIS MORNING AND EXPECT A DRY AND WARM DAY FOR THE
BULK OF THE AREA. INCREASING SOUTHERLY WINDS/WAA WILL SUPPORT
AFTERNOON HIGHS CLIMBING INTO THE MID TO UPPER 60S FOR MOST
LOCATIONS. PAIR OF MIDLEVEL WAVES...REMAINING LARGELY
UNPHASED...WILL THEN CROSS THE REGION OVERNIGHT. LATEST 00Z MODELS
CONTINUED SLOWER TREND AND PRECIP NOW LOOKS TO HOLD OFF UNTIL LATE
TONIGHT. SOUTHERN WAVE WILL BE THE MAIN FEATURE FOR OUR AREA.
HEALTHY DOSE OF CVA FROM SHARP CYCLONIC CURVATURE IN THE MID...AND
UPPER...LEVEL FLOW WILL SUPPORT GOOD UVM AND WEAK CYCLOGENESIS
ACROSS THE REGION. STILL EXPECT WIDESPREAD LIGHT-MODERATE RAIN AS
THIS FEATURE PASSES EARLY FRIDAY MORNING GIVEN THETA-E SURGE AHEAD
OF THE LOW AND PW VALUES RETURNING TO NEARLY 1.25 INCHES. LATER
TIMING WILL LIMIT OUR THUNDER POTENTIAL AS ALREADY MINUSCULE
PREFRONTAL INSTABILITY WANES AFTER SUNSET. NEUTRAL STABILITY
OVERNIGHT WILL AID THE SYNOPTIC FORCING THOUGH...FURTHER SUPPORTING
HIGH POPS AND MODEST QPF VALUES IN THE 0.2-0.5 INCH RANGE. OVERNIGHT
LOWS WILL REMAIN MILD IN WARM/MOIST AIR ADVECTION AHEAD OF THE
FRONT. EXPECT MINS ONLY IN THE UPPER 40S TO LOWER 50S FOR MOST
LOCATIONS.

&&

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 400 AM EDT THU APR 24 2014

WITH TREND TO A SLOWER AND MORE DOMINANT SOUTHERN STREAM
TROUGH...HAVE EXTENDED LIKELY POPS ACROSS EASTERN HALF OF THE AREA
INTO EARLY FRIDAY MORNING WITH NAM/GFS TIME HEIGHT SECTIONS
DEPICTING FAIRLY STEEP FRONTAL CIRCULATION IN DEFORMATION FORCING
PORTION OF THIS SYSTEM. EXACT PLACEMENT OF STRONGEST DEFORMATION
WILL DEPEND SOMEWHAT ON IMPACTS TO LOW/MID LEVEL WIND FIELD OF
NORTHERN STREAM TROUGH TRACKING ACROSS THE WESTERN GREAT LAKES. SOME
WEAK ELEVATED INSTABILITY MAY SUPPORT AN ISOLD TSTORM PARTICULARLY
ACROSS FAR SOUTHEAST EARLY FRIDAY...BUT CONFIDENCE MUCH TOO LOW FOR
INCLUSION AT THIS TIME. PRECIP TO EXIT EASTERN AREAS LATE MORNING OR
TOWARD MIDDAY WITH BREEZY/DRY CONDITIONS IN THE AFTERNOON AS
STRONGER LOW LEVEL DRY AIR ADVECTION WORKS INTO THE AREA BEHIND THE
FRONT. SECONDARY SHORT WAVE AND POCKET OF 850-700 HPA NOW ALSO
APPEARS TO BE A BIT MORE DELAYED AND CONTINUED TREND OF PREVIOUS
FORECAST IN PUSHING BACK TIMING OF LOW CHANCE -RW POPS UNTIL LATE
FRIDAY NIGHT. MIXING HEIGHTS ALSO NOT LOOKING QUITE AS IMPRESSIVE AS
PREVIOUS RUNS FRIDAY AFTERNOON...BUT FAIRLY DEEP MIXING FRIDAY
AFTERNOON SHOULD ALLOW FOR HIGHS FROM MID 60S TO LOWER 70S.

MAIN FORECAST CHALLENGE FOR SATURDAY WILL BE HOW FAR SOUTH SFC/NEAR
SFC FRONT PROGRESSES BEFORE STALLING. SETUP APPEARS TO FAVOR A SHARP
NORTH TO SOUTH THERMAL GRADIENT ACROSS THE AREA WITH AREAS ADJACENT
TO LAKE MICHIGAN LIKELY STRUGGLING TO THE 50 DEGREE MARK. NAM
CERTAINLY APPEARS TO BE AN OUTLIER WITH A FURTHER NORTH SFC TROUGH
POSITION SATURDAY AFTERNOON. DID ADD SOME SHARPENING TO THIS
GRADIENT FOR MAX TEMPS SATURDAY...BUT HAVE UTILIZED BLENDED
GFS/NAM/EC APPROACH. WHILE WEAK ISENTROPIC UPGLIDE WILL LIKELY
COMMENCE LATER SATURDAY AFTERNOON PARTICULARLY ACROSS WESTERN
PORTIONS OF THE AREA...ANY MOISTURE OF NOTE SHOULD BE HIGHLY
ELEVATED WHICH SHOULD SUPPORT NOTHING MORE THAN SPRINKLES AT BEST.

TRANSITION TO A MORE STABLE WAVE PATTERN TO FOLLOW FOR LATE WEEKEND
WITH BLOCKING TYPE PATTERN DEVELOPING. AMPLIFICATION OF THE PATTERN
WILL ALLOW FOR MID/UPPER RIDGING TO GET PINCHED FROM THE NORTHERN
GREAT LAKES INTO THE OHIO RIVER VALLEY WHICH WILL DELAY ANY MOISTURE
RETURN OF NOTE UNTIL LATER SUNDAY. TEMP FORECAST SOMEWHAT TRICKY FOR
SUNDAY WITH STRENGTHENING LOW LEVEL INVERSION AND INCREASING HIGH
CLOUDINESS POSSIBLY MAKING FOR A FEW DEGREES OF COOLING IN
COMPARISON TO SATURDAY. DEEPENING EASTERLY FLOW IN RESPONSE TO
PRESSURE FALLS TO THE WEST WILL MAINTAIN DRY LOW LEVEL TRAJECTORIES
AND HAVE MAINTAINED JUST SLIGHT CHANCE -RW POPS SUNDAY
AFTERNOON...RAMPING UP TO CHANCE SUNDAY NIGHT.

EC/GFS CONTINUE TO BE IN GENERAL AGREEMENT WITH A COMPLICATED
PHASING OF RETROGRADING SOUTHEAST CANADIAN AND CENTRAL CONUS PV
ANOMALIES FOR EARLY NEXT WEEK. THIS PHASING PRODUCES A SLIGHTLY MORE
NORTHWARD POSITION TO THE CONSOLIDATED MID/UPPER HEIGHT MINIMUM
TOWARD THE END OF THIS FORECAST PERIOD. WITH DETAILS IN THIS
SOLUTION LIKELY TO CHANGE OVER NEXT DAY OR TWO...HAVE GENERALLY
STAYED THE COURSE WITH BROADBRUSH CHANCE RW POPS THROUGH MUCH OF THE
MON-WED PERIOD WITH COOLER THAN NORMAL TEMPS PERSISTING.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 130 AM EDT THU APR 24 2014

VFR CONDITIONS EXPECTED TO PERSIST THROUGH MOST OF THE PERIOD.
WEAK WARM FRONT WILL LIFT NORTH ACROSS THE AREA THIS MORNING AND
MAY GENERATE A STRAY SPRINKLE AROUND KSBN BUT CEILINGS WILL REMAIN
WELL ABOVE 5 KFT. SHORTWAVE TROUGH AND ASSOCIATED SURFACE LOW WILL
CROSS THE AREA TOWARD THE END OF THE PERIOD BUT LATEST MODEL RUNS
SUGGEST RAIN AND LOWER CEILINGS WILL HOLD OFF UNTIL AFTER 06Z.

&&

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

&&

$$

SYNOPSIS...AGD
SHORT TERM...AGD
LONG TERM...MARSILI
AVIATION...AGD


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