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 302108
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
408 PM EST FRI JAN 30 2015

.SYNOPSIS...
ISSUED AT 405 PM EST FRI JAN 30 2015

LAKE EFFECT CLOUDS AND FLURRIES WILL CONTINUE TO DIMINISH THIS
EVENING AS HIGH PRESSURE BUILDS ACROSS THE REGION. LOW
TEMPERATURES TONIGHT WILL DROP BACK INTO THE TEENS. HIGHS ON
SATURDAY WILL BE IN THE 30S. A DEVELOPING WINTER STORM WILL
IMPACT THE REGION STARTING SATURDAY NIGHT AND CONTINUING INTO
SUNDAY. WINTER STORM WATCHES REMAIN IN EFFECT.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 405 PM EST FRI JAN 30 2015

BENIGN WEATHER EXPECTED THROUGH SATURDAY AS HIGH PRESSURE DRIFTS
ACROSS THE REGION. BANDS OF LAKE EFFECT CLOUDS AND FLURRIES HAVE
BEEN STEADILY CONTRACTING PAST COUPLE OF HOURS WITH THIS TREND
LIKELY TO INCREASE AS WE CLOSE IN ON THE EARLY EVENING HOURS. THE
CLEAR SKIES AND DIMINISHING WINDS WILL ALLOW LOWS TO DROP INTO
THE TEENS AS THE HIGH DRIFTS OVERHEAD.

THE REGION WILL BE ON THE WARM SIDE OF THE HIGH ON SATURDAY
ALLOWING AFTERNOON HIGHS TO CLIMB TO NEAR OR ABOVE
FREEZING...ALLOWING FOR TEMPORARILY IMPROVING ROAD CONDITIONS
PRIOR TO THE ARRIVAL OF THE SNOW SATURDAY EVENING.

&&

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 405 PM EST FRI JAN 30 2015

12 UTC MODELS/COBB OUTPUT ALONG WITH 09/15 UTC SREF ENSEMBLE
PLUMES LENDING INCREASED CONFIDENCE FOR SIG EVENT SAT NIGHT
THROUGH SUN NIGHT...LEADING TO PRIOR MIDDAY ISSUANCE OF WINTER
STORM WATCH FOLLOWING WPC/INTEROFFICE COORD. SW/BAJA VORTEX
PUMPING EXTREME MOISTURE TRANSPORT NWD. 4-6 G/KG PLUS WITHIN
850-500 MB EXTRUDED NWD FM SWRN MEXICO INTO INTMTN/CENTRAL ROCKIES
TO HARMONIOUSLY MELD WITH HIGH MOISTURE LADEN WRN VANCOUVER WAVE
INTO SAT. PRESENCE OF HUDSON BAY AND SWRN VORTEX TO AID IN PHASING
TO SHARPLY HEWN SEWD DIVING SHORTWAVE THROUGH NRN PLAINS INTO MID
MS VLY. INCREASINGLY RAMPED HGHT FALLS WITH LONG DURATION TO AID
IN LARGE SCALE ASCENT. PROLONGED EWD REACH OF HGHT ADJUSTMENTS
NOTED AS HFC IN EXCESS OF 100M/12HR SUN AM INTENSIFIES UPWARDS OF
180M/12 HR AS IT INTO SWRN OH/NRN KY BY 12 UTC MON.
EXTREME/PROLONGED MFLUX CONVERGENCE IN E-W FASHION THROUGH NRN IL
INTO NWRN OH PER I285/I290K NAM ISENTROPIC SFCS. 50 KT SWRLY
JETLET ORTHOGONAL TO ISENT SFCS MOVES EWD FM SERN MO UP OHIO BASIN
SUN AM TO NEAR KCVG BY 00 UTC MON. 7H TRACK IN LARGELY
OPEN/POSITIVE TILT TO WEAKLY CLOSED ALONG ROUTE 6 CORRIDOR AND
HINT OF TROWAL AT I285K JUST SOUTH...ALONG WITH TIGHTER ENSEMBLE
SPREAD LENDS HIR CONFIDENCE TO FARTHER NWD SWATH OF HEAVIEST
SNOWFALL. WHILE CONFIDENCE OF SIG EVENT/6 PLUS INCHES IS VERY
HIGH...EVENTUAL PLACEMENT AND DETAILS ALONG N/S GRADIENT EDGES
STILL EVOKE HESITANCE/UNCERTAINTY. THEREFORE ENTIRE CWA UNDER WSW
FOR 6 TO 12 INCHES POSSIBLE...WITH LATER RUNS PROVIDING SUFFICIENT
CONFIDENCE FOR UPG WARNING/ADV DECISIONS...LIKELY EARLY AM SUN AND
CERTAINLY BY NOON SHOULD DEFERENCE BE MADE TO 12 UTC SUN MODEL
OUTPUT. WHAT COULD GO WRONG...INCLUSION OF PLATES/NEEDLES IN DEEP
SUPERSATURATION ABOVE THE DGZ COULD LEAD TO MORE GRANULAR FLAKES
AND ANY FARTHER NWD TREND WOULD BEGIN TO GREATLY LESSEN FAR SRN
CWA SLR AS COLUMN WARMS...THOUGH SRN CWA NAM BUFKIT SITES FIRM IN
FROZEN/SNOW PTYPE PER ENERGY NOMOGRAM. RAMPED GRADIENT FLOW TO
BRING PD OF BLSN ESP LATE SUN AFTN/EVE AS OH VLY SFC LOW DEEPENS
ALONG TRACK THROUGH MID INTO UPR OH VLY.

BRIEF LES IN WAKE OF SYSTEM...THOUGH INITIAL BAND MAY SET WEST OF
CWA UNTIL BACKING FLOW BY DAYBREAK MON. THEREAFTER DRY AIR
INTRUSION ALONG WITH LOWERING/STRENGTHENING SUBSIDENCE INVERSION
SHOULD GREATLY MITIGATE NWRN CWA ACCUMS. WEAK CLIPPER SYSTEM INTO
GRTLKS TUE NIGHT/WED...FOLLOWED AGAIN BY AT LEAST WEAK LES
RESPONSE AS PRIMARY TROF AXIS SHARPENS FM HUDSON BAY INTO LWR
GRTLKS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1245 PM EST FRI JAN 30 2015

MARGINAL MVFR CIGS WILL PERSIST AT KSBN THROUGH THE AFTERNOON WITH
EVENTUAL TREND TO CLEARING SKIES TONIGHT. RADAR RETURNS AND SFC
REPORTS SHOWING LITTLE MORE THAN FLURRIES HERE AND THERE SO NO
VSBY IMPACTS EXPECTED.

AFTER 00Z SAT LITTLE IN THE WAY OF SENSIBLE WEATHER CONCERNS AS
HIGH PRESSURE DOMINATES.


&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...WINTER STORM WATCH FROM SATURDAY EVENING THROUGH SUNDAY EVENING
     FOR INZ003>009-012>018-020-022>027-032>034.

MI...WINTER STORM WATCH FROM SATURDAY EVENING THROUGH SUNDAY EVENING
     FOR MIZ077>081.

OH...WINTER STORM WATCH FROM SATURDAY EVENING THROUGH SUNDAY EVENING
     FOR OHZ001-002-004-005-015-016-024-025.

LM...NONE.
&&

$$

SYNOPSIS...MURPHY
SHORT TERM...MARSILI
LONG TERM...SKIPPER
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.