Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 220954
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
554 AM EDT TUE APR 22 2014

.SYNOPSIS...
ISSUED AT 414 AM EDT TUE APR 22 2014

A COLD FRONT CURRENTLY PASSING THROUGH THE REGION WILL USHER IN MUCH
COLDER AIR FOR TODAY AND TONIGHT. HIGHS WILL GENERALLY BE IN THE 50S
WITH OVERNIGHT LOWS AROUND 30. NORTHWEST WINDS MAY ALSO GUST TO
AROUND 30 MPH TODAY...MAKING IT FEEL EVEN CHILLIER DESPITE MOSTLY
SUNNY SKIES. SLOW MODERATION IN TEMPERATURES EXPECTED THROUGH THE
END OF THE WEEK BEFORE ANOTHER COLD FRONT ARRIVES ON FRIDAY.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 414 AM EDT TUE APR 22 2014

SURFACE REFLECTION OF COLD FRONT JUST NOW CROSSING THE AREA DESPITE
BULK OF THE PRECIP...ASSOCIATED WITH A SUBTLE PREFRONTAL
TROUGH...NOW EXITING EASTWARD. A FEW SHOWERS HAVE MANAGED TO DEVELOP
RIGHT ALONG THE FRONT AND EXPECT ISOLATED RAIN WILL CONTINUE IN OUR
EASTERN ZONES THROUGH THE EARLY MORNING HOURS UNTIL FRONT FULLY
CLEARS THE CWA AROUND 12Z. DRY CONDITIONS THEN EXPECTED FOR THE REST
OF THE SHORT TERM PERIOD AS MIDLEVEL RIDGING AND ASSOCIATED CANADIAN
SURFACE HIGH GRADUALLY BUILD INTO THE REGION. PERSISTENT CAA AND
NORTHWEST FLOW OFF THE STILL VERY COLD WATERS OF LAKE MICHIGAN WILL
MUTE THE DIURNAL RESPONSE TODAY WITH AFTERNOON TEMPS NOT MUCH
DIFFERENT THAN PRESENT VALUES. 850MB TEMPS EXPECTED TO DROP BELOW 0C
BY THE AFTERNOON...CAPPING TEMPS FOR MOST AREAS IN THE LOW TO MID
50S WITH ONLY UPPER 40S EXPECTED NEAR THE LAKE. EXPECT A FAIR AMOUNT
OF SUN BUT NORTHWEST SURFACE WINDS MAY ALSO GUST TO NEAR 30 MPH
GIVEN STRONG PRESSURE GRADIENT AND DECENT MIXING HEIGHTS...MAKING IT
FEEL SOMEWHAT CHILLIER. THIS WILL SET THE STAGE FOR A COLD NIGHT
ACROSS THE AREA AS WELL. CORE OF THE THERMAL TROUGH WITH 850MB TEMPS
AROUND -6C DOES SKIRT BY TO OUR NORTHEAST BUT STILL EXPECT NEARLY
IDEAL RADIATIVE CONDITIONS WITH CLEAR SKIES AND A LIGHT NORTHERLY
WIND. WILL THEREFORE LEAN TOWARD COOLER GUIDANCE WITH MIN TEMPS IN
THE UPPER 20S TO AROUND 30F...SUPPORTING AREAS OF FROST OVER MOST OF
THE CWA. GROWING SEASON IS NOT YET IN FULL SWING SO NO FROST/FREEZE
HEADLINES NECESSARY. WILL HOWEVER ISSUE AN SPS TO ALERT THOSE WITH
SENSITIVE OUTDOOR VEGETATION.

&&

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 414 AM EDT TUE APR 22 2014

LONG TERM FORECAST TRENDING TOWARDS COOLER AND POTENTIALLY WETTER
PERIOD BUT LOW CONFIDENCE AND UNCERTAINTY CONTINUE FOR THE UPCOMING
WEEKEND AND EARLY PART OF NEXT WEEK.

WEDNESDAY WILL BEGIN WITH HIGH PRESSURE OVER THE AREA AND A VERY
COOL START. PLENTY OF INSOLATION DURING FIRST PART OF DAY WILL
HELP TEMPS REBOUND INTO THE 50S MOST AREAS. NAM12 SHOWS LAKE SHADOW
MAKING GOOD INLAND PROGRESS LATE MORNING TO EARLY AFTERNOON. EXPECT
TEMPS IN LAKE SHORE COUNTIES WILL STRUGGLE TO REACH 50 AND NEARBY
INLAND COUNTIES TO CLIMB INTO LOWER TO MID 50S BEFORE BECOMING
STEADY FOR FALLING BACK IN THE AFTERNOON AS MARINE LAYER MOVES
FARTHER INLAND. BETTER MIXING OUTSIDE OF LAKE SHADOW SUGGEST HIGHS
IN THE UPPER 50S TO POSSIBLY LOWER 60S.

MOST MODELS STILL TRYING TO GENERATE SOME LIGHT QPF OVER CENTRAL AND
NW AREAS WED NIGHT WITH DEVELOPING LOW LEVEL JET AND WARM AIR
ADVECTION. FORECAST SOUNDINGS CONTINUE TO SHOW VERY DRY LOWER LEVELS
SO IT WILL BE DIFFICULT TO FULLY SATURATE. WILL CONTINUE WITH
SPRINKLE MENTION FOR NOW AND SEE HOW MUCH MOISTURE RETURN DEVELOPS
FOR POSSIBLE BUMP IN POPS NEXT FEW FORECASTS. BETTER CHANCE FOR RAIN
STILL LOOKS TO BE THURSDAY NIGHT AHEAD OF OCCLUDED FRONT AS LOW
PRESSURE MOVES INTO THE GREAT LAKES. GOOD SHORT WAVE AND ASSOCIATED
LIFT SHOWN BY MODELS WITH BRIEF THETA E AND PWAT SURGE. LIKELY POPS
ON TARGET WITH AMOUNTS OF ONE QUARTER TO POSSIBLY ONE HALF INCH WITH
HEAVIER SHOWERS.

MILD DAY FOLLOWS OCCLUDED FRONT FOR FRIDAY WITH TEMPS SIMILAR TO
THURSDAY AND NEAR OR SLIGHTLY ABOVE NORMAL. SECONDARY FRONT DRIVES
SOUTH FRIDAY NIGHT WITH CHANCE FOR LIGHT SHOWERS. THIS WILL HELP SET
UP A RATHER PRONOUNCED BAROCLINIC ZONE ACROSS INDIANA FOR THE
WEEKEND AND EARLY NEXT WEEK. UPPER AIR PATTERN BECOMES MORE
MERIDIONAL AND BLOCKY WITH STALLED SFC FRONT JUST TO OUR SOUTH. THIS
LOOKS TO KEEP A COOL EASTERLY FLOW IN PLACE AT THE SURFACE LEADING
TO RETURN OF BELOW NORMAL TEMPERATURES. UNCERTAINTY INCREASES THIS
WEEKEND AND EARLY NEXT WEEK FOR POPS SO RELIANCE ON ENSEMBLES AND
BLENDS UNTIL FINER DETAILS CAN BE SORTED OUT.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 554 AM EDT TUE APR 22 2014

SURFACE COLD FRONT HAS NOW CLEARED KSBN AND WILL CLEAR KFWA WITHIN
THE NEXT FEW HOURS. STRONG SURGE OF DRY AIR BEHIND THE FRONT IS
EXPECTED TO BRING MOSTLY CLEAR SKIES FOR THE REST OF THE TAF
PERIOD. TIGHT PRESSURE GRADIENT AND DEEP BOUNDARY LAYER MIXING
WILL SUPPORT WIND GUSTS OF AROUND 25 KTS FOR MUCH OF THE DAY
THOUGH.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR LMZ043-046.

&&

$$

SYNOPSIS...AGD
SHORT TERM...AGD
LONG TERM...LASHLEY
AVIATION...AGD


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