Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 262009
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
409 PM EDT SUN OCT 26 2014

.SYNOPSIS...
ISSUED AT 130 PM EDT SUN OCT 26 2014

HIGH PRESSURE WILL CONTINUE TO PROVIDE CLEAR SKIES AND MILD
TEMPERATURES INTO THE EVENING. AS THIS HIGH SLIDES EAST...A
DEVELOPING WARM FRONT WILL APPROACH TONIGHT WHICH SHOULD AID IN
INCREASING CLOUDS LATE. TEMPERATURES WILL FALL INTO THE 40S EARLY
TONIGHT BUT LIKELY LEVEL OFF AND EVEN RISE A FEW DEGREES LATE.
CLOUDS WILL HANG AROUND THE AREA MONDAY MORNING UNTIL THE WARM
FRONT PASSES AND SKIES BECOME PARTLY CLOUDY. HIGHS ON MONDAY WILL
WARM WELL INTO THE 70S ACROSS THE ENTIRE REGION...WITH A FEW
SOUTHERN LOCATIONS APPROACHING 80.

&&

.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 408 PM EDT SUN OCT 26 2014

HIGH PRESSURE DRIFTING OVER THE REGION TODAY PROVIDING CLEAR AND
MILD CONDITIONS. THIS HIGH WILL DRIFT EAST TONIGHT AS A WARM FRONT
DEVELOPS AND MOVES TOWARD THE AREA. WARM FRONT SHOULD CROSS THE
CWA ON MONDAY WITH VERY WARM TEMPS FOR LATE OCTOBER EXPECTED OVER
THE CWA.

12Z RAOBS AND MODEL SOUNDINGS SHOW A VERY DRY AIRMASS IN PLACE AND
AFTERNOON DEWPOINTS MIXING OUT INTO THE UPPER 20S AND LOWER 30S.
THIS PROBLEMATIC WITH RESPECT TO TRICKY LOW TEMPERATURE FORECAST
TONIGHT. IDEAL RADIATIONAL COOLING CONDITIONS EXPECTED EARLY THIS
EVENING WITH CLEAR SKIES AND LIGHT OR CALM WINDS AFTER SUNSET. 850MB
RIDGE EXPECTED TO PASS AFTER 06Z WITH SOUTHWEST LOW LEVEL JET
INCREASING TO BETWEEN 20 AND 30 KNOTS. GOOD THETA E SURGE EXPECTED
IN CONJUNCTION WITH THIS INCREASING LOW LEVEL JET SHOULD ALLOW A MID
CLOUD DECK TO DEVELOP AND SLOWLY LOWER TOWARD DAYBREAK. EXPECT
TEMPERATURES TO DROP RATHER RAPIDLY AFTER SUNSET THROUGH ABOUT 06Z
BEFORE AFOREMENTIONED WARM AIR ADVECTION AND CLOUD COVER INCREASE
AND AID IN LEVELING OFF TEMPS AND ALLOWING A RISE LATE. PREVIOUS
FORECAST HAD SITUATION HANDLED WELL AND TWEAKED TEMPS DOWN JUST A
BIT GIVEN THIS AFTERNOON DRYING BEING NOTED AND LATEST GUIDANCE
BLENDS.

NAM12 300K ISENTROPIC ANALYSIS SHOWS GOOD ORTHOGONAL COMPONENT OF
WINDS TO PRESSURE SURFACES SUGGESTING GOOD LIFT WITH INCREASING
MOISTURE. HOWEVER...CLOSER LOOK AT SYSTEM RELATIVE ISENTROPIC
INDICATES A MUCH WEAKER COMPONENT WITH WINDS NEARLY PARALLEL TO
PRESSURE SURFACES INDICATING A WEAKER CONTRIBUTION. WITH LOW LEVELS
INITIALLY VERY DRY PER RAOBS IT SHOULD BE A SLOW PROCESS TO SATURATE
OVERNIGHT. BEST LOW LEVEL JET FOCUS REMAINS NORTHWEST OF THE LOCAL
AREA SO LEANING TOWARD THE DRIER MODEL SOLUTIONS LATE TONIGHT AND
MONDAY MORNING. SHOULD SEE AN INCREASE IN CLOUD COVER WITH THETA E
ADVECTION SO TRENDING TOWARD PARTLY OR MOSTLY CLOUDY.

WARM FRONT SLIDES NORTH ON MONDAY. MORNING CLOUDS SHOULD MIX AND
LIFT NORTH WITH PERIOD OF SUN MIDDAY BEFORE CLOUDS INCREASE AGAIN
AHEAD OF MAIN SHORT WAVE AND APPROACHING COLD FRONT. HIGHS IN THE
LOWER TO MIDDLE 70S NORTH AND CENTRAL EXPECTED WITH SOUTHERN AREAS
MAKING A RUN AT 80. RECORD HIGHS FOR SBN AND FWA ARE 80 AT EACH
SITE.

&&

.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 408 PM EDT SUN OCT 26 2014

A FAST MOVING COLD FRONT WILL MOVE ACROSS THE AREA TUESDAY. GOOD LOW
LEVEL FORCING WITH SUFFICIENT UPPER AIR SUPPORT ALONG WITH
ADEQUATE MOISTURE SHOULD ALLOW NUMEROUS SHOWERS ALONG AND AHEAD OF
THE FRONT. REFINED THE TIMING OF THE SHOWERS WITH PRECIPITATION
ENDING FROM WEST TO EAST BY TUESDAY EVENING. THE PATTERN WILL REMAIN
ACTIVE WITH A SECOND FRONT MOVING ACROSS THE AREA LATE THURSDAY
NIGHT/EARLY FRIDAY. KEPT HIGHS FRIDAY COLD WITH CHILLY CONDITIONS
EXPECTED FRIDAY AND SATURDAY. CONCERN FOR LAKE EFFECT RAIN OR SNOW
SHOWERS WITH DELTA T VALUES TOPPING 20C PER COLDER ECMWF BY LATE
FRIDAY INTO SATURDAY. ADDED A CHANCE FOR SHOWERS FRIDAY. THERE IS A
CHANCE FOR A MIX BY LATE IN THE DAY AS 850 MB TEMPS DROP BELOW
0C...HOWEVER FOR NOW...KEPT PRECIPITATION ALL RAIN GIVEN LINGERING
UNCERTAINTY. GIVEN A HIGH ZONAL HEMISPHERIC PATTERN UPSTREAM...THE
COLD AIR INTRUSION SHOULD BE BRIEF WITH HIGHS RECOVERING TO AROUND
50 BY SUNDAY.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 129 PM EDT SUN OCT 26 2014

CLEAR SKIES AND VFR CONDITIONS INTO THIS EVENING. A WARM FRONT
WILL APPROACH OVERNIGHT AND CLOUDS EXPECTED TO DEVELOP AHEAD OF
THIS BOUNDARY. A FEW MODELS INDICATING SOME MVFR AND EVEN IFR
CIGS POSSIBLE TOWARD DAYBREAK INTO MID MORNING. WITH LOWER LEVELS
INITIALLY VERY DRY AND NOT ALL MODELS ON BOARD WITH THIS...OPTED
TO KEEP TAFS VFR AND DRY FOR NOW BUT WILL MONITOR THROUGH THE
EVENING.


&&

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

$$

SYNOPSIS...LASHLEY
SHORT TERM...LASHLEY
LONG TERM...SKIPPER
AVIATION...LASHLEY


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