Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 251931
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
331 PM EDT WED MAR 25 2015

.SYNOPSIS...
ISSUED AT 1118 AM EDT WED MAR 25 2015

FOR THE REST OF TODAY WE WILL BE IN BETWEEN LOW PRESSURE SYSTEMS
AS SKIES REMAIN FAIRLY CLOUDY. HIGH TEMPERATURES TODAY WILL RANGE
FROM THE LOWER 50S IN SOUTHERN MICHIGAN TO NEAR 70 IN SOUTHEASTERN
INDIANA. TONIGHT A LOW WILL BE MOVING THROUGH THE OHIO RIVER
VALLEY WHICH WILL BRING ANOTHER CHANCE FOR PRECIPITATION. MAINLY
RAIN IN THE REGION WITH FAR NORTHERN INDIANA AND SOUTHERN MICHIGAN
HAVING A CHANCE FOR RAIN AND SNOW. LOW TEMPERATURES TONIGHT WILL
RANGE FROM THE LOWER 30S IN SOUTHERN MICHIGAN TO THE UPPER 40S
ALONG THE OHIO RIVER.

&&

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 331 PM EDT WED MAR 25 2015

MAIN FOCUS IS ON TIMING/AMOUNTS/PTYPE OF PCPN THROUGH THE AREA
TONIGHT INTO THURSDAY MORNING AS A FRONTAL WAVE TRACKS NE THROUGH
THE OH VALLEY...

TEMPS HAVE UNDERPERFORMED TODAY THANKS TO LOW STRATUS THAT HAS
REMAINED LOCKED IN UNDER BRIEF DRYING/SUBSIDENCE ALOFT. THIS
COOLER BOUNDARY LAYER PROFILE SHOULD ALLOW RAIN TO MIX OR CHANGE
OVER TO SNOW LATER TONIGHT/THU AM...QUESTIONS ARE WHEN/WHERE/HOW
MUCH. SYNOPTICALLY...PHASING/APPROACH OF SHORTWAVE ENERGY DROPPING
SE FROM THE UPPER MIDWEST AND A SEPARATE PV ANOMALY EMERGING INTO
THE CENTRAL PLAINS WILL HELP REORIENT ISOTHERMS ALONG THE
DEFORMATION AXIS...AND THEREFORE TIGHTEN/DEEPEN THE LOW-MID LEVEL
FRONTOGENETICAL RESPONSE INTO OH/IN LATER TONIGHT INTO THURSDAY
MORNING. THIS TIGHTENING OFF THE THERMAL FIELD WILL NO DOUBT
STRENGTHEN A GREAT LAKES UPPER JET STREAK...WITH THE LOCAL AREA
PLACED IN THE RIGHT ENTRANCE REGION OF THIS FEATURE BY THIS TIME.
MODELS AGREE FOR THE MOST PART ON ALL BUT FAR NW ZONES GETTING
INTO THE 750-600 MB PORTION OF THE FRONTAL CIRCULATION...WITH
MOISTURE (PER 3-4 G/KG PUSH ON 290K CHARTS) APPEARING SUFFICIENT
FOR A DECENT BURST OF PCPN. THERE WILL BE A SHARP CUT OFF ON THE
NW FRINGE WHICH UNFORTUNATELY LOOKS TO BE OVER OR JUST SE OF THE
SOUTH BEND/ELKHART AREA MAKING FOR A LOW CONFIDENCE POP/QPF
FORECAST HERE. LOOKS LIKE A SLAM DRUNK ACROSS SOUTHERN/EASTERN
ZONES WHERE CATEGORICAL POPS AND QPF AMOUNTS UP TO NEAR A HALF
INCH WERE RETAINED (ALTHOUGH CONVECTION INTO THE WESTERN OH VALLEY
COULD LIMIT NWD TRANSPORT OF MOISTURE AND THEREFORE AMOUNTS A BIT)

AS FOR PTYPE...PCPN WILL BEGIN AS RAIN ALONG THE INITIAL/NARROW FGEN
BAND INTO CENTRAL PORTIONS OF THE AREA LATER THIS EVENING/EARLY
OVERNIGHT...THEN LIKELY MIX WITH OR CHANGE TO A BRIEF PERIOD OF SNOW
LATER TONIGHT/THU AM AS DEEPER LIFT/COOLING WORKS IN. MODELED WET
BULB TEMPERATURES IN THE LOWEST 2KFT FEET MARGINAL FOR RAIN OR SNOW
MAKING FOR A DIFFICULT PTYPE FCST (OPTED FOR MIX WORDING AS A
RESULT). ALSO ADDED IN SOME LIGHT ACCUMS (LOW CONFIDENCE
...DUSTING-1") ALONG/SE OF A MONTICELLO-WARSAW-HILLSDALE
LINE...ALTHOUGH WPC 1-3" AMOUNTS POSSIBLE IF A QUICKER/FULL
CHANGEOVER OCCURS. COOL/DRY OTHERWISE IN WAKE OF THIS SYSTEM INTO
THURSDAY AFTERNOON.

&&

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 331 PM EDT WED MAR 25 2015

LONGWAVE TROF IN EAST/RIDGING WESTERN STATES FOR MUCH OF LONG
TERM...FAVORING WELL BLO NORMAL INTO ERLY NEXT WEEK.
SHARPENED SERN/NWRN POP GRADIENT WRT EXITING RAFL THU AM. BY ERLY
AFTN SFC LOW INTO SWRN PA TO EFFECTIVELY LIGATE/SHUNT EWD WARM
CONVEYOR BELT MOISTURE FEED. THEREAFTER...PROLONGED DEEP LAYER COLD
AIR ADVECTION THROUGH LATTER PART OF WEEK AS NORTH CENTRAL CANADA
SOURCED ARCTIC RIDGE PLUNGES INTO WRN GRTLKS BY SAT. LARGE SCALE
SUBSIDENT/DRY AIRMASS WITH PWAT GRADUALLY FALLING TO AROUND 0.10
INCHES INTO FRIDAY. CONTD THU NIGHT CHC FLURRIES AMID POS TILTED LOW
AMPLITUDE SHORTWAVE MOVG INTO WRN GRTLKS. HAVE TERMINATED LOW CHC
POPS FRI...THOUGH ACQUIESCE TO CHC FLURRIES FRI AMID MID TEENS LK/8H
DIFFERENTIALS WITH POTNL OFF BOTH LKS MI AND HURON DURING THE DAY
ALONG WITH MODESTLY CYCLONIC 925-8H FLOW.

NEXT STRONG NRN STREAM SYSTEM WITH 150-200M/12 HR FALLS MOVES INTO
NRN GRTLKS SUN. RETURN MOISTURE FLOW INADVOF SYSTEM APPEARS RATHER
ANEMIC. CONTD LOW END SHRA POPS. FEW CHNGS FROM BLEND
THEREAFTER...SAVE FOR DY5/7 RAISED MAX TEMPS SWRLY RETURN
FLOW...CLOSER TO EC ENSEMBLE MEAN. STILL BLO NORMAL SUN...CLOSER TO
NORMAL BY DY7/8 AS PATTERN BECOMES SOMEWHAT IN FLUX FLATTER/OR TROF
AXIS SHUNTS EWD...WHICH MAY ALLOW FOR GREATER TSRA FOCUS FM TX EWD
THROUGH GULF STATES.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1241 PM EDT WED MAR 25 2015

EXTENSIVE IFR TO LOW MVFR STRATUS DECK WILL LIKELY HOLD ON THROUGH
LATE AFTERNOON UNDER SUBSIDENT MID LVL DRY SLOT. 4MB/3HR PRESSURE
RISES WILL CONTINUE TO SUPPORT GUSTS TO NEAR 25 KNOTS THROUGH MID
AFTERNOON BEFORE QUICKLY SUBSIDING LATE AFTN/EVE AS GRADIENT
RELAXES NEAR TRAILING BAROCLINIC ZONE. RETAINED OPTIMISTIC MIX OUT
TO VFR THIS EVENING...ALTHOUGH WOULD NOT BE SURPRISED IF A BKN
MVFR STRATOCU DECK REMAINS LOCKED IN. DETERIORATING CONDITIONS TO
MVFR/IFR EXPECTED LATER TONIGHT/THU MORNING AT KFWA AS A FRONTAL
WAVE TRACKING THROUGH THE OH VALLEY SPREADS MORE PCPN IN. 12Z
GUIDANCE HAS CONTINUED TREND TOWARD COOLER THERMAL PROFILES WITH
RAIN POSSIBLY MIXING WITH OR CHANGING TO A PERIOD OF MODERATE WET
SNOW BEFORE ENDING TOWARD MID MORNING. ATTM IT APPEARS AS IF THE
BULK OF THE PCPN AND ASSOCIATED FLIGHT RESTRICTIONS SHOULD PASS
JUST SSE OF KSBN.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 5 PM EDT THIS AFTERNOON FOR LMZ043-
     046.

&&

$$

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


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