Area Forecast Discussion
Issued by NWS Northern Indiana

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS63 KIWX 180755
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
355 AM EDT SAT OCT 18 2014

.SYNOPSIS...
ISSUED AT 348 AM EDT SAT OCT 18 2014

COOL CONDITIONS ARE EXPECTED TODAY AS ANOTHER UPPER LEVEL
DISTURBANCE APPROACHES THE AREA. THIS DISTURBANCE WILL BRING A
CONTINUED CHANCE OF RAIN SHOWERS TODAY...WITH SOME LINGERING LAKE
EFFECT RAIN SHOWERS PERSISTING INTO LATE AFTERNOON AND EARLY
EVENING. OUTSIDE OF LAKE EFFECT CLOUDINESS...SKIES WILL CLEAR THIS
EVENING AND WINDS WILL DIMINISH ALLOWING FOR COLD TEMPERATURES TO
NEAR THE FREEZING MARK FOR MANY LOCATIONS...AND THE POTENTIAL FOR
FROST. HIGH TEMPERATURES TODAY WILL RANGE FROM THE UPPER 40S TO
LOWER 50S. LOW TEMPERATURES TONIGHT WILL RANGE FROM THE UPPER 20S
TO MID 30S FOR MOST LOCATIONS. HOWEVER...LAKE EFFECT CLOUDS MAY
KEEP LOWS TONIGHT IN THE MID TO UPPER 30S ACROSS NORTHWEST INDIANA
AND SOUTHWEST LOWER MICHIGAN HOWEVER.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 348 AM EDT SAT OCT 18 2014

TWO FOLD CONCERNS FOR THE SHORT TERM PERIOD WITH MOST SIGNIFICANT
BEING FROST/FREEZE POTENTIAL TONIGHT.

COLD FRONT/INITIAL SHORTWAVE HAS SHIFTED SOUTH OF THE AREA WITH
COLDER AIR CONTINUE TO STREAM INTO THE REGION. NEXT PIECE OF ENERGY
WAS RAPIDLY APPROACHING FROM THE NW. THIS ALONG WITH 850 MB TEMPS
DROPPING BELOW ZERO WILL ALLOW FOR A UPTICK IN LAKE EFFECT CLOUD
COVER AND SHOWER ACTIVITY TOWARDS 12Z. UPSTREAM RADARS SHOWING A FEW
NARROW BANDS OF SHOWERS TAKING SHAPE NOW AND THIS SHOULD EXPAND
FURTHER WITH PEAK TIME FRAME IN THE 12 TO 18Z PERIOD. HAVE ADJUSTED
ONSET OF HIGHEST POPS CLOSER TO THE 12Z TIME FRAME AND EXPANDED
INLAND A BIT WITH SUBSEQUENT EXPANSION OF ALL POPS ACROSS THE AREA
FOR AT LEAST A PERIOD OF LIGHT SHOWERS/DRIZZLE IN MOST LOCATIONS.
VERY LITTLE DIURNAL SWING IN TEMPERATURES TODAY WITH CLOUDY SKIES
EXPECTED INTO THIS AFTERNOON BEFORE DRIER AIR BEGINS TO WORK IN FROM
NE.

NW FLOW WILL REMAIN OFF THE LAKE INTO THIS EVENING WITH 925 MB RH
PLUMES SHOWING GREATER THAN 80 PERCENT RH VALUES DOWNWIND OF THE
LAKE WHICH PERSISTS INTO THE OVERNIGHT HOURS WITH THIS AREA SHIFTING
EAST TOWARDS 12Z SUNDAY AS FLOW BECOMES MORE WESTERLY. CLEAR SKIES
AND LIGHT WINDS LOOK QUITE LIKELY ACROSS THE EASTERN HALF OR SO OF
THE AREA WITH GUIDANCE NUMBERS ALL POINTING TOWARDS LOWS IN THE
LOWER 30S. GIVEN CONFIDENCE IN AREAS TO WIDESPREAD FROST AND AFTER
MUCH COLLABORATION WITH SURROUNDING OFFICES WILL HOIST FREEZE WATCH
FOR AREAS CURRENTLY FORECAST TO DROP TO 33 DEGREES OR LOWER FOR
OVERNIGHT LOWS TO ACCOUNT FOR LOCALLY COOLER POTENTIAL (28 TO 32
DEGREE RANGE) IN BOUNDARY LAYER VS SENSOR LEVEL MEASUREMENT. MOST IF
NOT ENTIRE CWA WILL LIKELY WARRANT SOME SORT OF HEADLINE BUT WITH
CLOUD COVER AMOUNT AND TIMING STILL A HUGE ISSUE...DON`T WANT TO
LOCK DAY SHIFT INTO ADVISORY/WARNING SITUATION DESPITE CURRENTLY
FAVORABLE SETUP IN PARTS OF THE AREA.

&&

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 348 AM EDT SAT OCT 18 2014

MAIN ITEM OF INTEREST IN THE LONG TERM WILL BE A CLIPPER LIKE
SYSTEM DIGGING ACROSS THE GREAT LAKES EARLY IN THE WEEK PROVIDING
FOR THE NEXT CHANCE OF RAIN. QUIETER CONDITIONS WILL FOLLOW FROM
TUESDAY NIGHT THROUGH THE END OF THE FORECAST PERIOD.

ON SUNDAY...LAKE EFFECT CLOUDINESS SHOULD PERSIST ACROSS FAR
NORTHWEST PORTIONS OF THE AREA ALTHOUGH DEPTH OF LAKE INDUCED
INSTABILITY WILL BECOME PROGRESSIVELY MORE SHALLOW WITH LOWERING
INVERSION HEIGHTS UNDER THE INFLUENCE OF SYNOPTIC SCALE SUBSIDENCE.
SOME BACKING OF LOW LEVEL WINDS IS EXPECTED SUNDAY MORNING WITH
APPROACH OF LOW LEVEL RIDGE AXIS WHICH SHOULD YIELD SOME EASTWARD
ADVECTION OF LAKE EFFECT CLOUDINESS. OUTSIDE OF LAKE EFFECT
CLOUDS...MAINLY CLEAR SKIES ARE EXPECTED IN THE MORNING...BUT
STRENGTHENING MID LEVEL WAA SHOULD ALLOW FOR MID LEVEL DECK TO
OVERSPREAD THE AREA FROM WEST TO EAST IN THE AFTERNOON HOURS. THE
LOWER INVERSION HEIGHTS ON SUNDAY SHOULD RESULT IN MIXING HEIGHTS
LIMITED TO AROUND 900 HPA WHICH SHOULD LIMIT HIGHS FROM LOWER 50S
FAR NORTHEAST TO THE MID 50S SOUTHWEST.

BY SUNDAY NIGHT...ATTENTION WILL SHIFT TO NEXT NORTHWEST FLOW WAVE
SPILLING OVER THE UPPER RIDGE ACROSS THE UPPER MS VALLEY. SOME WEAK
LOW LEVEL MOISTURE POOLING SHOULD COMMENCE ON SUNDAY ALONG LOW LEVEL
TROUGH AXIS DOWNSTREAM OF THIS WAVE...WITH THIS WEAK MOISTURE AXIS
SHIFTING INTO THE WESTERN GREAT LAKES SUNDAY NIGHT. FAIRLY STRONG
MID/UPPER LEVEL BAROCLINICITY SHOULD ALSO EXIST WELL DOWNSTREAM OF
THIS WAVE ACROSS THE OHIO VALLEY WHICH MAY INDUCE SOME WEAK
MID/UPPER LEVEL FRONTOGENETIC RESPONSE SUNDAY NIGHT. LOW LEVEL
MOISTURE WILL BE EVEN MORE MARGINAL ACROSS AREAS PRONE TO THIS
ELEVATED FORCING HOWEVER. GIVEN COMBINATION OF ABOVE FACTORS HAVE
MAINTAINED BROADBRUSH LOW CHANCE POPS ACROSS ENTIRE CWA SUNDAY NIGHT.

UPPER LEVEL FORCING TO INCREASE BY EARLY MONDAY AS UPSTREAM WAVE
AMPLIFIES ACROSS THE GREAT LAKES REGION...ALTHOUGH LATEST ITERATIONS
OF THE EC SEEM TO BE A LITTLE LESS AGGRESSIVE AND MORE DELAYED IN
THIS REGARD. THIS MAY RESULT IN A SLIGHTLY MORE PROGRESSIVE LOW
LEVEL MOISTURE AXIS THAN PREVIOUS INDICATIONS...SO HAVE HELD TO
INHERITED HIGH CHANCE POPS ACROSS THE EAST. IT IS POSSIBLE POPS WILL
NEED TO BE INCREASED ACROSS THE EAST IN NEXT FEW FORECAST CYCLES
DEPENDING ON EVOLUTION OF UPPER TROUGH. PRECIP MAY END AS A PERIOD
OF PATCHY DRIZZLE LATE MONDAY AFTERNOON INTO MONDAY NIGHT AS UPPER
TROUGH TRACKS ACROSS THE AREA. STILL SOME INDICATIONS OF BETTER
PHASING OF UPPER SYSTEM EAST OF THE AREA ON TUESDAY WHICH COULD LEND
TO ISOLD SHOWER POTENTIAL LINGERING ACROSS THE EAST...SO NO CHANGES
MADE IN THIS REGARD.

TEMPERATURES WILL BE SLOW TO MODERATE THROUGH THE PERIOD AS MORE
PHASED UPPER LOW CONSOLIDATES ACROSS EASTERN CONUS LATER IN THE
WEEK...RESULTING IN ONLY A SLOW EASTWARD MIGRATION OF CENTRAL CONUS
UPPER RIDGING. MORE PRONOUNCED MODERATION IN TEMPERATURES IS
EXPECTED TOWARD THE END OF THE PERIOD HOWEVER.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 137 AM EDT SAT OCT 18 2014

MVFR CONDITIONS EXPECTED TO CONTINUE THROUGH MUCH OF THE PERIOD AS
LAKE EFFECT CLOUDS/LIGHT SHOWERS AND GUSTY WINDS EXPAND OVER THE
NEXT COUPLE OF HOURS AND PERSIST INTO AT LEAST MID AFTERNOON.
IMPACTS WILL REMAIN LONGEST AT KSBN WITH VFR CIGS EVENTUALLY
TAKING SHAPE AT KFWA AS DRIER AIR BEGINS TO FILTER IN.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...FREEZE WATCH FROM LATE TONIGHT THROUGH SUNDAY MORNING FOR
     INZ005>009-016>018-024>027-032>034.

MI...FREEZE WATCH FROM LATE TONIGHT THROUGH SUNDAY MORNING FOR
     MIZ078>081.

OH...FREEZE WATCH FROM LATE TONIGHT THROUGH SUNDAY MORNING FOR OHZ001-
     002-004-005-015-016-024-025.

LM...SMALL CRAFT ADVISORY UNTIL 6 AM EDT SUNDAY FOR LMZ043-046.

&&

$$

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


VISIT US AT WWW.WEATHER.GOV/IWX (ALL LOWER CASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSNORTHERNINDIANA
WWW.TWITTER.COM/NWSIWX
WWW.YOUTUBE.COM/NWSNORTHERNINDIANA






USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.