Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 171740
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
140 PM EDT FRI OCT 17 2014

.SYNOPSIS...
ISSUED AT 1200 PM EDT FRI OCT 17 2014

THIS AFTERNOON WILL FEATURE DRY CONDITIONS AND INCREASING CLOUDS
IN ADVANCE OF A COLD FRONT...WITH HIGHS FORECAST TO REACH THE MID
TO UPPER 60S. MUCH COOLER AIR WILL MOVE INTO THE REGION TONIGHT
INTO SATURDAY BEHIND THIS COLD FRONT. SKIES WILL BE MOSTLY CLOUDY
ALONG WITH THE CHANCE FOR A FEW SHOWERS AS SEVERAL UPPER LEVEL
DISTURBANCES DROP THROUGH. LOWS TONIGHT WILL DROP INTO THE 40S AND
ONLY RECOVER TO NEAR 50 DEGREES ON SATURDAY.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 351 AM EDT FRI OCT 17 2014

POTENT UPPER LEVEL SYSTEM WAS MOVING ACROSS THE ARROWHEAD OF
MINNESOTA AND WILL BEING TO SHIFT MORE SOUTHEAST TODAY INTO THE
CENTRAL GREAT LAKES. BRIEF UPPER LEVEL RIDGING WAS SHIFTING
ACROSS THE REGION AS WE SPEAK WITH A SURGE OF WARMER LOW LEVELS
TEMPERATURES. HOWEVER...EXTENSIVE STRATUS DECK ACROSS MOST OF THE
AREA WAS KEEPING ITS EFFECTS IN CHECK AND THIS WILL REMAIN THE
CASE THIS MORNING DESPITE SOME AREAS OF CLEARING ESPECIALLY WEST.
DRY CONDITIONS WILL EXIST THROUGH MUCH OF THE DAY AS MAIN EFFECTS
FROM THE UPPER LEVEL WAVE WILL WAIT TILL TONIGHT TO IMPACT THE
REGION. THAT BEING SAID...BEST LIFT AND INSTABILITY LOOKS TO PASS
JUST TO THE NORTH OF THE FORECAST AREA IN ASSOCIATION WITH THE
LOW TRACK. HOWEVER...NORTHERN SECTIONS STILL APPEAR TO BE IN
STORE FOR A PERIOD OF LIGHT SHOWERS THIS EVENING INTO THE
OVERNIGHT HOURS WITH ALL AREAS SEEING EXTENSIVE CLOUD COVER. HAVE
INCREASED PRECIP CHANCES TONIGHT AS WELL AS CLOUD COVER ACROSS
ENTIRE AREA GIVEN MODEL TREND AND EXPANSIVE STRATOCU DECK
UPSTREAM FROM MINNESOTA BACK INTO THE DAKOTAS. HIGHS TODAY WILL
ONLY CLIMB INTO THE LOW TO MID 60S WITH LOWS TONIGHT FALLING BACK
INTO THE 40S.

&&

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 351 AM EDT FRI OCT 17 2014

ACTIVE NORTHWEST FLOW PATTERN WILL BRING PERIODIC CHANCES OF SOME
RAIN SHOWERS THROUGH THE MIDDLE OF NEXT WEEK ALONG WITH BELOW
NORMAL TEMPERATURES.

FOR SATURDAY MORNING...LOCAL AREA SHOULD BE SITUATED BETWEEN TWO
DISTINCT SHORT WAVES. THE FIRST OF THESE WAVES BRINGING BRIEF
PERIOD OF SYNOPTIC RAIN SHOWER CHANCES FRIDAY NIGHT WILL BE
DEPARTING TO THE EAST...WHILE NEXT UPSTREAM WAVE ASSOCIATED WITH
A 100 KNOT UPPER JET STREAK WILL BE DIGGING INTO THE SOUTHERN
GREAT LAKES DURING THE AFTERNOON. HAVE MAINTAINED HIGH CHANCE
RAIN SHOWER POPS ACROSS NORTHWEST PORTIONS OF THE AREA DUE TO
COMBINATION SYNOPTIC FORCING/LAKE EFFECT...ALTHOUGH
SUBSIDENCE/DRY MID LEVEL AIR ADVECTING INTO THE REGION LATER IN
THE DAY SHOULD TEND TO DIMINISH COVERAGE DURING THE MID/LATE
AFTERNOON HOURS. WELL MIXED LOW LEVELS UNDER INFLUENCE OF LOW
LEVEL CAA WILL MAKE FOR A RAW DAY WITH NORTHWEST WIND GUSTS TO
AROUND 25 MPH. LOW LEVEL THERMAL PROGS AND GOOD DEAL OF LOW CLOUD
COVER SHOULD LIMIT MAX TEMPS TO AROUND 50 MOST LOCATIONS...OR
PERHAPS UPPER 40S ACROSS NORTHERN LOCATIONS.

PASSAGE OF THIS WILL LEAD TO STRONG SYNOPTIC SCALE SUBSIDENCE
SATURDAY NIGHT...ALTHOUGH LAKE EFFECT CLOUDS WILL LIKELY PERSIST
THROUGH MUCH OF THE NIGHT. ASIDE FROM LAKE EFFECT CLOUDS...SKIES
SHOULD TREND TO MOSTLY CLEAR WITH DIMINISHING WINDS AS LOW LEVEL
RIDGE AXIS SHIFTS INTO WESTERN GREAT LAKES REGION. THIS SHOULD
PROMOTE COLD CONDITIONS WITH LOWS IN THE 30 TO 35 DEGREE RANGE
ACROSS MOST LOCATIONS OUTSIDE OF AREAS DOWNWIND OF LAKE MICHIGAN
WHERE LOW LEVEL DEW POINTS SHOULD BE SLIGHTLY HIGHER. NOT MUCH
CHANGE MADE TO TEMPS/FROST DELINEATION WITH BETTER CHANCE OF MORE
WIDESPREAD FROST AND POSSIBLE SUBFREEZING TEMPS ACROSS
EAST/NORTHEAST LOCATIONS.

GUIDANCE HAS BEEN FAIRLY CONSISTENT IN NEXT RIDGE RIDING CLIPPER-
LIKE SYSTEM DIGGING INTO THE GREAT LAKES REGION MONDAY. A NARROW
LOW LEVEL THETAE RIDGE SHOULD ADVECT INTO THE AREA SUNDAY NIGHT
INTO EARLY MONDAY AND MAY BE SOMEWHAT SLOW IN SHIFTING EASTWARD
DUE TO DIGGING NATURE OF AFOREMENTIONED WAVE. DID MAINTAIN CHANCE
RAIN SHOWER POPS LATE SUNDAY NIGHT DUE TO POSITIVE LOW LEVEL
THETAE ADVECTION AND SOME MID/UPPER LEVEL FRONTOGENETIC RESPONSE
DOWNSTREAM OF THIS WAVE. MID TO HIGH CHANCE POPS MAINTAINED INTO
MONDAY WITH STRONGER UPPER FORCING SHIFTING INTO THE REGION.
PRECIP CHANCES BEGIN TO DIMINISH MONDAY NIGHT...ALTHOUGH SOME
POSSIBILITY EXISTS FOR HUDSON BAY VORT MAX TO GET INGESTED INTO
WESTERN PERIPHERY OF GREAT LAKES UPPER TROUGH WHICH COULD PROLONG
ISOLD/SCT RAIN SHOWERS ACROSS THE FAR EAST INTO EARLY TUESDAY.
AMPLIFICATION OF UPPER PATTERN INTO WED/THU WILL RESULT IN
TRANSITION TO A MORE STABLE WAVE PATTERN AND ONLY SLIGHT EASTWARD
PROGRESSION OF CENTRAL CONUS UPPER RIDGE THROUGH THE END OF THE
PERIOD...PROVIDING ONLY MINIMAL TEMPERATURE MODERATION THROUGH DAY
7.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 131 PM EDT FRI OCT 17 2014

RAPID INCREASE IN CLOUD COVERAGE AS POST FRONTAL CAA CONTINUES TO
INFILTRATE NORTHERN INDIANA INTO THE EVENING/OVERNIGHT. AS LAKE
INDUCED INSTABILITY INCREASES OVERNIGHT...SHRA RESPONSE TO
INCREASE DOWNWIND OF LAKE MICHIGAN...PEAKED WITHIN 06-16 UTC
TIMEFRAME FOR FUELING/ALT CONDITIONS AT KSBN. SLIGHTLY HIR
CIGS/LESSER SHRA COVERAGE FARTHER INLAND AND HAVE KEPT KFWA ABOVE
CRITICAL LEVELS. SOME SIG GUSTS INTO MID 20KT RANGE THIS AFTERNOON
AS 1000-850MB LAPSE RATES CONTINUE TO STEEPEN/PROMOTE MOMENTUM
XFER. RELAXATION OF CYCLONIC LOW LEVEL FLOW AND INCREASED DEEP
LAYER SUBSIDENCE SHOULD BRING END TO LAKE REPONSE SHRA BY
MID/LATE SAT AFTERNOON WITH RETURN TO VFR MET CONDITIONS BY SAT
EVENING...WITH LATER FORECAST ITERATIONS TO RESOLVE FURTHER.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 6 AM EDT SUNDAY FOR LMZ043-046.

&&

$$

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


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