Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 242051
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
451 PM EDT TUE MAR 24 2015

.SYNOPSIS...
ISSUED AT 436 PM EDT TUE MAR 24 2015

A LOW PRESSURE SYSTEM WILL TRACK INTO THE REGION LATE TONIGHT
INTO WEDNESDAY MORNING...BRINGING RAIN AND POSSIBLY A FEW
THUNDERSTORMS TO THE AREA. LOWS TONIGHT WILL RANGE FROM THE UPPER
20S OVER NORTHEAST PORTIONS OF THE AREA TO THE UPPER 30S
SOUTHWEST...THOUGH TEMPERATURES ARE EXPECTED TO RISE INTO THE 40S
OVER THE ENTIRE AREA BY WEDNESDAY MORNING. BECAUSE OF THE
INTIIALLY COLDER TEMPERATURES...THERE IS A CHANCE OF FREEZING RAIN
IN THE NORTHEAST. AS TEMPERATURES WARM OVERNIGHT...ANY FREEZING
RAIN SHOULD TRANISITION TO RAIN. NO ICE ACCUMULATION IS EXPECTED.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 328 PM EDT TUE MAR 24 2015

COOL/DRY LOW LEVEL EASTERLY FLOW ON THE SW PERIPHERY OF AN EASTERN
LAKES SFC ANTICYCLONE WILL GIVE WAY TO A PERIOD OF RAIN OVERNIGHT.
THIS WILL OCCUR AS A VIGOROUS MID LEVEL SHORTWAVE (NOW ADVANCING
THROUGH KANSAS PER AFTERNOON WATER VAPOR) RACES TOWARD THE LOWER
GREAT LAKES WHILE TAKING ON A NEGATIVE TILT. INITIAL SURGE OF
850-700 MB THETA-E ADVECTION WILL BRING INCREASING CLOUDS AND
CHANCES FOR SHOWERS INTO WESTERN PORTIONS OF THE FA THIS
EVENING...ALTHOUGH HELD POPS IN LOW-MID CHC CATEGORY GIVEN FIGHT
WITH ANTECEDENT DRY AIRMASS. DEEP UVM PLUME ASSOCIATED WITH THE
DYNAMIC SHORTWAVE AND EXCELLENT MOISTURE TRANSPORT (850 MB
DEWPOINT SURGE TO 5-6C) WITHIN A 50-60KT LLJ WILL ALLOW MORE
WIDESPREAD/HEAVIER PCPN TO PIVOT NE THROUGH THE LOCAL AREA BTW
06-12Z. A FEW RUMBLES OF THUNDER ALSO REMAIN POSSIBLE GIVEN STRONG
FORCING AND STEEPENING MID LEVEL LAPSE RATES. PCPN MAY BEGIN AS A
BRIEF PERIOD OF -FZRA NORTHERN/EASTERN ZONES OVERNIGHT BEFORE
WAA/LATENT HEATING QUICKLY OVERWHELMS THE NEAR SURFACE
LAYER/INVERSION...BUT NOT EXPECTING ANY ICE ACCUMULATIONS/IMPACTS
ATTM. OTHERWISE...TEMPS MAY DROP A FEW DEGREES EARLY THIS EVENING
BEFORE STEADILY RISING OVERNIGHT.

MID LEVEL SUBSIDENCE/DRYING WILL OVERSPREAD THE AREA ON WEDNESDAY IN
THE WAKE OF THIS UPPER WAVE...WITH LINGERING SHOWERS/DRIZZLE
POSSIBLE EARLY IN THE MORNING ALONG THE SFC OCCLUSION. TEMPS WILL BE
NOTICEABLE MILDER TOMORROW IN WAKE OF THIS FEATURE BUT JUST HOW WARM
WE GET REMAINS HIGHLY UNCERTAIN AND DEPENDENT ON HOW QUICKLY
LINGERING STRATUS HANGS ON AND WHERE TRAILING SFC BOUNDARY LAYS OUT
BY AFTERNOON. OPTED FOR A MODEL BLEND FOR NOW WHICH CAME OUT A FEW
DEGREES COOLER THAN THE PREV FCST.

&&

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 328 PM EDT TUE MAR 24 2015

TOPSY-TURVY SPRING PATTN THIS PD AS BATTLE BTWN WINTER AND SPRING
CONTS.

SECONDARY FNTL WAVE XPCD TO DVLP WED NIGHT ALG TRAILING CDFNT IN
BEHIND VIGOROUS CYCLONE LIFTING UP ACRS THE LAKES ON WED. GOOD
00-12Z AGREEMENT ON PLACEMENT OF BNDRY TO NR/ALG OH RVR AND XPC BULK
OF PCPN TO LINE UP ALG NRN EDGE OF LL THETA-E RIDGE. WILL CONTRACT
GOING POP GRADIENT FURTHER ESP FAR NW TO ACCOUNT FOR LK MI NEG
THETA-E SINK. OTRWS SECONDARY NRN STREAM TROUGH AMPLIFYING SEWD ACRS
THE LAKES THU NIGHT WILL PROPEL ASSOCD ARCTIC FNT THROUGH THE REGION
W/SHARPLY COLDER TEMPS FOLLOWING IN ITS WAKE FOR FRI-SAT AS YET
ANOTHER UNSEASONABLY STG RIDGE BLDS SEWD OUT OF SRN CANADA. IN FACT
MEX/EC MOS BASED GUIDANCE IS SIMILAR W/ADVERTISE DEPARTURES OF 20-25
DEGREES BLO NORMAL.

PATTN ALOFT XPCD TO FLATTEN LT WEEKEND INTO EARLY NEXT WEEK
W/MODERATING TEMPS BACK TO NORMAL IN THE LOW-MID 50S BY DY8 (TUE).

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1236 PM EDT TUE MAR 24 2015

HIGH PRESSURE CENTERED ACROSS THE EASTERN LAKES WILL CONTINUE TO
FUNNEL LOW LEVEL DRY/COOL EASTERLY FLOW INTO NORTHERN INDIANA THIS
AFTERNOON/EVENING. VFR CONDITIONS WILL RESULT WITH JUST A GRADUAL
LOWERING/INCREASE OF MID-HIGH LEVEL CLOUDS WITH TIME. CONDITIONS
WILL RAPIDLY DETERIORATE LATER TONIGHT AS RAIN SHIELD ASSOCIATED
WITH A FAST MOVING/YET VIGOROUS MID LEVEL SHORTWAVE TRACKS TOWARD
THE GREAT LAKES OVERSPREADS. DRYING AND GRADUAL MIX UP/OUT OF POST
OCCLUSION STRATUS EXPECTED TOMORROW AS WINDS VEER WSW IN ADVANCE
OF THE NEXT SYSTEM MODELED TO TAKE AIM ON THE REGION WED NIGHT-THU
AM.


&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 5 PM EDT
     WEDNESDAY FOR LMZ043-046.

&&

$$

SYNOPSIS...MCD
SHORT TERM...STEINWEDEL
LONG TERM...T
AVIATION...STEINWEDEL


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