Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 230546
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
1246 AM EST FRI JAN 23 2015

.SYNOPSIS...
ISSUED AT 1230 AM EST FRI JAN 23 2015

HIGH PRESSURE WILL REMAIN OVER THE REGION TODAY BUT CLOUDS WILL
REMAIN TRAPPED OVER THE REGION KEEPING SKIES MOSTLY CLOUDY. LOW
TEMPERATURES TONIGHT WILL RANGE FROM THE TEENS NORTH TO UPPER 20S
SOUTH. HIGHS ON FRIDAY WILL GENERALLY BE IN THE 30S.

&&

.UPDATE...
ISSUED AT 800 PM EST THU JAN 22 2015

00Z RAOBS FROM ILX/DTX AND REGIONAL AMDAR SOUNDINGS CONTINUE TO DEPICT
A VERY THIN LOW LEVEL SATURATED LAYER THIS EVENING. SATELLITE
IMAGERY DURING THE LATE AFTERNOON HOURS WAS SHOWING SOME EROSION
OF LOW CLOUDS ACROSS CENTRAL WISCONSIN/LOWER MICHIGAN. SOUTHWARD
EROSION OF THIS DECK HAS SLOWED OVER THE PAST FEW HOURS AND
SUSPECTING THAT WITH LIGHT SOUTHWEST LOW LEVEL FLOW DEVELOPING
OVERNIGHT ON WESTERN SIDE OF LOW LEVEL ANTICYCLONE THAT THESE LOW
CLOUDS MAY PERSIST THROUGH MUCH OF THE NIGHT GIVEN PERSISTING LOW
LEVEL INVERSION. DID NUDGE UP SKY COVER OVERNIGHT INTO EARLY
FRIDAY MORNING WITH AN ASSOCIATED HEDGE TO SLIGHTLY INCREASE MIN
TEMPS INTO MAINLY THE LOWER TO MID 20S GIVEN THIS THINKING. ANY
AREAS WHICH DO EXPERIENCE MORE SUBSTANTIAL CLEARING OVERNIGHT WILL
HAVE A BETTER CHANCE TO DROP THROUGH THE LOWER 20S HOWEVER. OTHER
THAN SKY COVER AND MINOR TEMP TWEAK...NO OTHER SUBSTANTIAL CHANGES
MADE AT THE CURRENT TIME.

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 500 PM EST THU JAN 22 2015

BROAD STRETCHING OF MID-LEVEL TROF OVER THE GREAT LAKES BETWEEN THE
SOUTHERN STREAM STORM AND THE NEXT CLIPPER MOVING OUT THE CANADIAN
ROCKIES. BOUNDARY LAYER AND SURFACE HIGH PRESSURE EXTENDING FROM THE
CENTRAL PLAINS INTO THE GREAT LAKES EXPECT TO WEAKEN THROUGH FRIDAY
EVENING. MAY SEE SOME FOG / LOW STRATUS EARLY IN THE MORNING FRIDAY
BUT OTHERWISE NO MEASURABLE PRECIPITATION IS EXPECTED.

AS THE HIGH PRESSURE WEAKENS...EXPECT TO SEE THE LOW LEVEL
INVERSION ERODE DURING THE EARLY MORNING HOURS FRIDAY. FRIDAYS MAX
TEMPERATURES SHOULD INCREASE A FEW DEGREES OVER TODAY.

SHORT TERM AND HIGH RES MODELS IN GOOD AGREEMENT FOR THE NEXT 24-30
HOURS AND HAVE ONLY MODIFIED THE CURRENT FORECAST GRIDS SLIGHTLY
OVER PREVIOUS GRIDS.

&&

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 500 PM EST THU JAN 22 2015

THE CHALLENGES IN THIS PERIOD INCLUDE THE TRACK...AMOUNT OF SNOW AND
TYPE OF PRECIPITATION WITH THE CLIPPER SYSTEM SUNDAY INTO EARLY
SUNDAY NIGHT. NCEP AND OTHER MODELS CONTINUE TO STRUGGLE WITH THE
HANDLING OF THE SYSTEM. A VERY LARGE SPREAD OF GFS ENSEMBLE MEMBERS
TRACK AND CENTRAL PRESSURE OF THE SURFACE LOW WERE INDICATIVE OF THE
ISSUES HANDLING OF THIS SYSTEM. GFS ENSEMBLE CENTRAL PRESSURE
DIFFERENCES RANGE FROM 980 MB TO AROUND 1000 MB. HAVE REJECTED THE
ECMWF TRACK WITH ITS SOUTHERN SOLUTION IN LIEU OF A MORE NORTHERN
SOLUTION SUPPORTED BY THE GFS. MANY GFS ENSEMBLE MEMBERS INCLUDING
THE OPERATIONAL RUN FAVOR A LOW TRACK OVER FAR SOUTH LOWER MICHIGAN.
THIS TRACK IS SUPPORTED BY CLIPPER CLIMATOLOGY AND CIPS ANALOGS.
ISENTROPIC LIFT ON THE 290K SURFACE WITH SPECIFIC HUMIDITIES OVER
3G/KG SUPPORT SNOWFALL AMOUNT OF GENERALLY 2 TO 4 INCHES OVER FAR
NORTHEAST AREAS...WITH MUCH LESSER AMOUNTS FARTHER SOUTHWEST.
OTHERWISE...FOR THE REST OF THIS UPCOMING WEEK...CHALLENGES WITH THE
EXTENT OF ARCTIC AIR OVER THE AREA AND THE TIMING OF CLIPPER SYSTEMS
IN STRONG NW FLOW. FOR NOW...KEPT MONDAY THROUGH WEDNESDAY BELOW
NORMAL...WITH MODERATING TEMPERATURES THURSDAY.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1232 AM EST FRI JAN 23 2015

LOW CLOUDS REMAIN LOCKED UNDER STRONG INVERSION WITH SURFACE HIGH
PRESSURE OVER THE REGION. DO NOT EXPECT THIS MVFR CLOUD DECK TO
DISSIPATE OVERNIGHT AS SOUTHWEST FLOW ALOFT IS LOCKING INVERSION
IN PLACE AND SATELLITE SHOWS CLOUD DECK EXPANDING. LATEST HIRES
GUIDANCE INDICATES INVERSION TO HOLD THROUGH FRIDAY WITH MOISTURE
TRAPPED OVER OUR AREA. SUBSIDENCE COULD WORK ON THE THIN LAYER
DURING THE DAY BUT WOULD ONLY EXPECT SOME BREAKS TO DEVELOP IN
AFTERNOON VERSUS FULL CLEARING. THUS HAVE KEPT TAFS IN THE MVFR
RANGE FOR THE PERIOD.

&&

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

$$

UPDATE...MARSILI
SYNOPSIS...LASHLEY
SHORT TERM...LEWIS
LONG TERM...SKIPPER
AVIATION...LASHLEY


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