Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 140047
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
847 PM EDT SUN APR 13 2014

.SYNOPSIS...
ISSUED AT 830 PM EDT SUN APR 13 2014

SHOWERS AND SCATTERED THUNDERSTORMS WILL BECOME MORE PREVALENT
TONIGHT AS AN UPPER LEVEL DISTURBANCE APPROACHES THE REGION FROM
THE PLAINS. A COLD FRONT ASSOCIATED WITH THIS SYSTEM WILL TRACK
ACROSS THE REGION ON MONDAY...BRINGING COLDER AND BLUSTERY
CONDITIONS. RAIN WILL TAPER IN COVERAGE DURING THE DAY
MONDAY...BUT ANOTHER DISTURBANCE WILL BRING A CHANCE OF LIGHT SNOW
ACCUMULATIONS FOR MONDAY NIGHT.

&&

.UPDATE...
ISSUED AT 830 PM EDT SUN APR 13 2014

AN AREA OF SHOWERS AND ISOLATED THUNDERSTORMS ASSOCIATED WITH
SMALL SCALE UPPER VORT MAX SHOULD EXIT FAR NORTHWEST PORTIONS OF
THE AREA OVER THE NEXT OVER. LULL IN PRECIP WILL BE RELATIVELY
SHORT LIVED AS STRONGER UPPER LEVEL SHORT WAVE WILL CONTINUE TO TRACK
INTO NORTHWEST INDIANA OVERNIGHT. A LARGE AREA OF ENHANCED LOW
LEVEL MOISTURE TRANSPORT NOTED PER LATEST RAP ANALYSIS ACROSS THE
MID MS RIVER VALLEY WILL SHIFT EASTWARD AND EXTEND FROM THE LOWER
OHIO VALLEY INTO THE SOUTHERN GREAT LAKES BY 09Z. A LARGE AREA OF
RAIN/EMBEDDED THUNDERSTORMS COINCIDING WITH THIS STRONGER LOW
LEVEL MOISTURE TRANSPORT ACROSS SOUTHEAST MISSOURI WILL CONTINUE
TO EXPAND NORTHEASTWARD OVERNIGHT...BRINGING WIDESPREAD
RAIN/EMBEDDED THUNDER TO MOST OF THE FORECAST AREA THROUGH EARLY
MONDAY MORNING. NORTHWARD ADVECTION OF 1.25-1.40 INCH PWAT AXIS
INTO THE AREA OVERNIGHT AND STRENGTHENING LOW LEVEL FRONTAL
CIRCULATION SHOULD PROMOTE SOME HEALTHY RAINFALL AMOUNTS POSSIBLY
APPROACHING AROUND AN INCH ACROSS WESTERN PORTIONS OF THE AREA
WHICH COULD LEAD TO SOME MINOR FLOODING CONCERNS GIVEN RECENT WET
PERIOD/MOIST SOILS. MAIN TWEAKS TO FORECAST THIS EVENING WERE TO
SLIGHTLY INCREASE POPS OVERNIGHT IN ASSOCIATION WITH ABOVE
MENTIONED TRENDS...ALONG WITH SLIGHT ADJUSTMENT TO HOURLY TEMP
CURVE ACROSS THE NORTHWEST COOLER TEMPS RESIDE INITIALLY DUE TO
EARLIER MARINE INFLUENCE. BEST CHANCE OF THUNDER APPEARS TO BE
DURING THE OVERNIGHT HOURS...WHERE SLIGHT ENHANCEMENT TO WEAK
ELEVATED INSTABILITY IS EXPECTED IN ASSOCIATION WITH LOW LEVEL
MOIST TONGUE.

&&

.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 328 PM EDT SUN APR 13 2014

VIGOROUS LOW PRESSURE OVR KS THIS AFTN WILL LIFT QUICKLY NEWD INTO
THE MI THUMB BY DAYBREAK TOMORROW AND PROPEL A STG CDFNT EWD ACRS
THE AREA. SO FAR WARM SECTOR HAS BEEN A DUD WITH THIS SYS OWING TO
POOR MSTR RTN UNDERNEATH STEEP EML AND SEE LTL EVIDENCE THAT WILL
CHANGE INTO EARLY EVE.

BETTER PROSPECTS FOR RAINFALL XPCD LT TONIGHT AHD AND ALG SFC FNTL
BNDRY. HWVR WKNG CAP WITHIN ZONE OF FVRBL THETA-E AND SUSTAINED LL
WAA STILL WARRANTS HOLDING ONTO SOME POPS NW THIRD THROUGH EVENING.
OTRWS STG POST FNTL CAA WEDGE FOLLOWS MON AM W/CRASHING SFC TEMPS.
LINGERING POST FNTL SHRA XPCD IN THE MORNING FOLLOWED BY LARGELY DRY
CONDS IN THE AFTN ASSOCD/W MID LVL DRY SLOT OF EXITING SYS ALOFT.

&&

.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 328 PM EDT SUN APR 13 2014

FOCUS OF FORECAST WILL BE ON ARRIVAL OF UNSEASONABLY COLD AIR AND
ACCUMULATING SNOWFALL AT THE START OF THE PERIOD.

COLD FRONT SHOULD BE LONG GONE BY MONDAY EVENING WITH THE REGION IN
A VERY BRIEF LULL IN PRECIP TO START THINGS OUT. THIS WILL QUICKLY
CHANGE AS A DISTURBANCE MOVES ALONG THE FRONT AND BRINGS ANOTHER
QUICK SHOT OF INCREASED MSTR AND LIFT. MODELS DO VARY ON EXACTLY HOW
MUCH QPF BUT IN GENERAL PAINT THE NEED FOR LIKELY TO CAT POPS FOR
MOST AREAS FOR A PERIOD...MAINLY IN THE 3Z TO 9Z TUES TIME FRAME.
HAVE BROKE GRIDS INTO 3 HOUR BLOCKS TO TRY TO ADD SOME DETAIL IN
TERMS OF TIMING. GIVEN RATHER PRONOUNCED/FAST ARRIVING PUNCH OF COLD
AIR...MIX POTENTIAL FOR PRECIP LOOKING MORE LIMITED WITH 1000-850 MB
THICKNESS AND SFC TEMPS ALL POINTING TOWARDS ALL SNOW. THE BIGGEST
CHALLENGE LIE WITH HOW MUCH PRECIP FALLS AND POTENTIAL
ACCUMULATIONS. IMPRESSIVE 850 MB DROP FOR MID APRIL WITH VALUES FROM
-8 TO - 10 C DURING BEST PRECIP WINDOW. AT THIS TIME...THINK MANY
AREAS WILL SEE SOME WET SNOWFLAKES TO START THINGS OFF IN THE
EVENING...WITH THIS SNOW BEING LESS WET WITH TIME AS COLDER AIR
SETTLES IN AND SNOW RATIOS INCREASE SOMEWHAT. IF WE WERE STILL
ENTRENCHED IN THE GENERALLY COLD PATTERN...WE MIGHT BE LOOKING AT
SEVERAL INCHES OF SNOW STICKING AROUND AND CAUSING A LOT OF
PROBLEMS. HOWEVER...DESPITE THE COLD AIR ARRIVING...ROAD/GROUND
TEMPS HAVE WARMED SUBSTANTIALLY GIVEN THE 70S OF THE PAST COUPLE OF
DAYS. THIS WILL LIKELY ALLOW FOR MELTING OF A LOT OF THE
SNOWFALL...ESPECIALLY ON ROADS. HOWEVER...IF SNOW CAN COME DOWN HARD
ENOUGH IT MAY BE ABLE TO ACCUMULATE AND STICK AROUND BRIEFLY INTO
PARTS OF TUESDAY AS HIGHS STRUGGLE THROUGH THE 30S TO NEAR 40. GRIDS
REFLECT ACCUMULATIONS OF 1 TO 3 INCHES WITH HIGHEST AMOUNTS IN SE
AREAS WHERE MSTR WILL LINGER LONGER. AGAIN...IT NEEDS TO BE STRESSED
THAT MUCH OF THIS SNOW MAY NOT ACCUMULATE IN THE EVENING BUT
OVERNIGHT...ROADS COULD BECOME SLIPPERY IN SOME AREAS AS OVERNIGHT
LOWS PLUMMET THROUGH THE 20S. FORECAST WILL NEED FINE TUNING FURTHER
OVER THE NEXT 12 TO 24 HOURS.

ONCE THIS SYSTEM PASSES BY...DRIER WEATHER WILL SETTLE IN UNTIL
THURS NGT BEFORE THE NEXT SYSTEM BEGINS TO APPROACH THE REGION WITH
CHANCES FOR SHOWERS. TEMPS WILL CLIMB BACK INTO THE 50S AND POSSIBLY
60S.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 830 PM EDT SUN APR 13 2014

LEAD SHORT WAVE WILL CONTINUE TO BRING A PERIOD OF RAIN SHOWERS
AND PERHAPS AN ISOLATED THUNDERSTORM TO KSBN OVER THE NEXT HOUR. A
BRIEF LULL IN RAIN SHOWER COVERAGE IF POSSIBLE AFTER 01Z...BUT
RAIN WILL BECOME MORE WIDESPREAD OVERNIGHT WITH SOME EMBEDDED
THUNDER AS A SHORT WAVE TROUGH LIFTS NORTHEAST INTO THE AREA. AN
AXIS OF ENHANCED MOISTURE WILL ALSO ADVECT INTO NORTHERN INDIANA
OVERNIGHT AHEAD OF THE UPPER TROUGH/COLD FRONT WHICH SHOULD ALSO
ALLOW FOR A PERIOD OF MODERATE TO HEAVY RAIN...MAINLY IN THE 06Z-
12Z TIMEFRAME. WITH INSTABILITY QUITE LIMITED IN MAGNITUDE HAVE
RESTRICTED THUNDER MENTION TO VCTS AT THIS TIME. SOUTH WINDS
GUSTS ARE EXPECTED TO INCREASE OVERNIGHT AS SFC PRESSURE FALLS
OVERSPREAD SOUTHERN GREAT LAKES...WITH GUSTY NORTHWEST WINDS TO 30
KNOTS ON MONDAY BEHIND THE FRONT. IFR CONDITIONS ARE ALSO EXPECTED
WITH THE PERIODS OF HEAVIER RAIN LATE TONIGHT INTO EARLY
MONDAY...EVENTUALLY IMPROVING TO MVFR BEHIND THE FRONT TOWARD
MIDDAY MONDAY.

&&

.MARINE...
ISSUED AT 328 PM EDT SUN APR 13 2014

AREAS OF FOG BEING INTRODUCED TO NEARSHORE WATERS WITH WEB CAMS
SHOWING FOG OFFSHORE...MORE THAN LIKELY MORE IN THE 3 TO 5 NM
RANGE. TRENDS WILL BE MONITORED FOR NEED FOR MARINE DENSE FOG
ADVISORY BUT MAIN THREAT SHOULD REMAIN IN OPEN WATERS.

WILL ALSO HOIST SMALL CRAFT ADVISORY STARTING LATER TONIGHT AND
CONTINUING THROUGH AT LEAST MONDAY IF NOT INTO TUESDAY. POTENTIAL
FOR A PERIOD OF GALE FORCE GUSTS BUT HAVE KEPT WORDING TONED DOWN
FOR THE TIME BEING WITH A FEW GUSTS TO 35 KTS.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...SMALL CRAFT ADVISORY FROM 2 AM TO 8 PM EDT MONDAY FOR LMZ043-046.

&&

$$

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


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