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000
FXUS63 KIWX 110930 CCA
AFDIWX

AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE NORTHERN INDIANA
529 AM EDT TUE MAR 11 2014

.SYNOPSIS...
ISSUED AT 523 AM EDT TUE MAR 11 2014

TEMPERATURES WILL BE CLOSE TO NORMAL TODAY...HOWEVER MUCH COLDER
AIR WILL BEGIN TO INFILTRATE THE REGION LATER TONIGHT THROUGH
WEDNESDAY. A STRONG LOW PRESSURE WILL TRACK EAST FROM THE PLAINS
AND INTO SOUTHERN INDIANA OVERNIGHT. THIS SYSTEM WILL BRING RAIN
TO THE REGION THAT WILL TRANSITION TO ALL SNOW BY WEDNESDAY
MORNING. SIGNIFICANT SNOW AMOUNTS ARE POSSIBLE...ALONG WITH
BLOWING SNOW AS THE SYSTEM INTENSIFIES ACROSS PENNSYLVANIA DURING
THE DAY.

&&

.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 523 AM EDT TUE MAR 11 2014

INTENSE 150-160KT 3H JETSTREAK INTO NRN BC THIS AM LEADING TO ENERGY
BIFURCATION WITH STRONG/PROGRESSIVE MID TROPOSPHERIC TROF CONTG EWD
THROUGH CNTL ROCKIES TODAY AND WELL TUCKED REX DROPPING SWD INTO SRN
NV INTO WED. MEANWHILE A NRN SPLIT OF EPAC ENERGY HAS ALIGHTED NRN
PERIPHERY OF WRN RIDGE AND WILL SOON PHASE WITH WRN SPOKE OF NERN
CANADIAN VORTEX AS THE SECONDARY DROPS SWD THROUGH NRN
ALBERTA...OFFERING POTENTIAL TRIFECTA PHASING AS DEEP TROF MOVES
INTO WRN GRTLKS BY 12 UTC WED. LEESIDE CYCLOGENETIC STRETCHING
ALREADY UNDERWAY WITH EMERGENT WRN KS LOW TRACKING EWD TO WRN MO BY
EVENING. THEREAFTER CONSTERNATION MOUNTS WITH QUITE SKEPTICAL 00 UTC
NAM IDENTIFYING LOW LEVEL THERMAL DISCONTINUITY MUCH FARTHER NWD
THAN CONSENSUS AND PRIOR NAM ITERATIONS. NAM ALSO DEEPER/SLOWER/MORE
ROBUST THAN SEEN PRIOR WITH STRONG 7H CLOSED CIRCULATION TRACKING
ACRS NRN CWA FM NWRN IN ON KVPZ TO KDTW LINE 12-18 UTC WED WHILE
DEEPENING 65M. THIS WITH STRONG TROWAL PRESENCE...IF VERIFIED COULD
EFFECTIVELY NEARLY DOUBLE MAX SNOW SWATH AMOUNTS...ESPECIALLY IN
LIGHT OF STEEP MID/UPR LEVEL LAPSE RATES/PRESENCE OF CONVECTIVELY
UNSTABLE PARCELS IN FAR NRN CWA. WHILE NAM DISCOUNTED...HAVE HELD
ONTO MID/LATE SECOND PERIOD WATCH IN DEFERENCE TOWARD NEED FOR 12
UTC MODEL ANALYSIS TO FINE TUNE WARNING/ADVISORIES AND AMOUNTS.
LARGE SPREAD OF POTENTIAL OUTCOMES DENOTED WITH CONTINUATION OF SREF
PLUME MEMBERS WELL SCATTERED ABOUT THE MEAN AND INHERENT
CONDITIONALITY ON UPSTREAM PHASING. SLIGHT MOD TO GRIDS/TOTAL
QPF/SNOW AMNTS FARTHER NORTH GIVEN EFFICIENT MOISTURE TAP PRESENTED
WITH INITIAL 6 G/KG 1000-850MB MOISTURE LAID OUT ALONG OLD FNTL
BNDRY SW-S FOLLOWED BY INTENSE MFLUX CONVERGENCE WITH BROAD GT 8
G/KG AIRMASS REACHING I70 CORRIDOR.

&&

.LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY)
ISSUED AT 523 AM EDT TUE MAR 11 2014

LONG TERM PERIOD TO BEGIN WITH DEPARTING STORM SYSTEM WEDNESDAY
NIGHT. UPPER LEVEL TROUGH AXIS WILL LIKELY LINGER ACROSS EASTERN
PORTIONS OF THE AREA DURING THE EVENING WITH SOME LINGERING LIGHT
SNOW SHOWERS OR FLURRIES STILL A POSSIBILITY. VERY COLD AIR TO
ADVECT INTO THE REGION WEDNESDAY NIGHT WILL SET UP. FRESH SNOW COVER
AND MAGNITUDE OF THIS AIR MASS SHOULD YIELD LOWS IN THE SINGLE
DIGITS ABOVE ZERO MOST LOCATIONS WITH MAIN LIMITING FACTOR TO THE
BOTTOM REALLY DROPPING OUT BEING FAIRLY WELL MIXED LOW LEVELS UNDER
THIS COLD ADVECTION. COULD APPROACH RECORD OR NEAR RECORD LOWS FOR
EARLY THURSDAY MORNING (FWA/1 SET IN 1960...AND SBN 1/SET IN 1896).

THE APPROACH OF LOW LEVEL RIDGE AXIS THURSDAY WILL ALLOW FOR BACKING
LOW LEVEL WINDS AND THE ONSET OF A PERIOD OF STRONGER WARM ADVECTION
THAT WILL EXTEND THROUGH THURSDAY NIGHT. THIS SHOULD SET THE STAGE
FOR RESPECTABLE DIURNAL TEMPERATURE SWINGS...PARTICULARLY ACROSS THE
SOUTHWEST WITH THE EARLIER ONSET OF LOW LEVEL WAA WHERE HIGHS OF
AROUND 30 OR LOWER 30S ARE POSSIBLE. ONGOING WARM ADVECTION THURSDAY
NIGHT WILL LIKELY LEAD TO NON-DIURNAL TEMPERATURE TENDENCIES WITH
RISING TEMPS. EVEN WITH THE POSSIBILITY OF FRESH SNOWCOVER TONIGHT
INTO WEDNESDAY...MAY STILL BE A BIT TOO COOL DURING THE OVERNIGHT
HOURS ON THURSDAY GIVEN THE STRENGTH OF THIS WARM ADVECTION AND WILL
JUST SLIGHTLY NUDGE TEMPERATURES UP AT THIS TIME.

FRIDAY STILL SHAPING UP TO BE A RELATIVELY MILD DAY WITH LOW LEVEL
THERMAL RIDGING IN PLACE IN ADVANCE OF NEXT PROGRESSIVE SHORT WAVE
DIVING SOUTHEAST THROUGH MEAN WESTERN CONUS/WESTERN CANADIAN RIDGE.
SOME WEAK FRONTAL RESPONSE POSSIBLE AS THIS SHORT WAVE
APPROACHES...ALTHOUGH TIMING QUITE DIFFICULT AT THIS FORECAST
DISTANCE DUE TO PROGRESSIVE NATURE OF THE PATTERN. THUS...HAVE GONE
CONSERVATIVE ON POPS AND WILL LIMIT MENTION TO SLIGHT CHANCE -RA
FRIDAY NIGHT.

FOR SATURDAY...UPPER VORT LOBE ROTATING AROUND WESTERN FRINGE OF
HUDSON BAY UPPER LOW SHOULD BRING ANOTHER SHOT OF COLD AIR BACK TO
THE REGION FOR THE WEEKEND. AS ZONE OF STRONGER DPVA DROPS INTO THE
REGION...SCATTERED SNOW SHOWERS ARE A POSSIBILITY BUT EXPECTED
MAGNITUDE OF LOW/MID LEVEL DRY AIR ADVECTION SHOULD LIMIT THIS
POTENTIAL AND WILL MAINTAIN JUST SLIGHT/LOW CHANCE SNOW SHOWER
MENTION FOR SATURDAY NIGHT/SUNDAY. WHILE RETURN TO MUCH BELOW NORMAL
TEMPERATURES STILL LOOKS REASONABLE FOR THE END OF THE
PERIOD...OVERALL PROGRESSIVE NATURE OF THE PATTERN SHOULD ALLOW FOR
MODERATION JUST AFTER THIS FORECAST VALID PERIOD.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 126 AM EDT TUE MAR 11 2014

MAIN AVIATION FORECAST CHALLENGES WILL CENTER ON FOG POTENTIAL
OVERNIGHT AND POTENTIAL OF PRECIPITATION TOWARD THE END OF THE
FORECAST PERIOD. LOCAL AREA TO BE POSITIONED IN COL TONIGHT WHICH
WILL PROVIDE GENERALLY LIGHT AND VARIABLE WINDS. HAVE NOTED SOME
DIMINISHMENT IN MID/HIGH CLOUD COVER ACROSS NORTHWEST
INDIANA/NORTHEAST ILLINOIS OVER THE PAST FEW HOURS...WITH GREATEST
MID CLOUD COVERAGE OVERNIGHT INTO EARLY TUESDAY MORNING EXPECTED
TO THE NORTH OF THE TERMINALS. COMBINATION OF PARTLY CLOUDY SKIES
AND LIGHT WINDS SHOULD CONTINUE TO LEND TO SOME RADIATIONAL
COOLING. CROSSOVER TEMPS LIKELY TO BE REACHED AND WILL CONTINUE
TO MENTION MVFR AND PERIODIC IFR VSBYS WITH THE 06Z TAFS THROUGH
EARLY TUESDAY MORNING. A WEST TO EAST ORIENTED SFC TROUGH WILL
TAKE SHAPE ON TUESDAY IN RESPONSE TO LEAD SHORT WAVE KICKING OUT
OF THE ROCKIES. THIS SHOULD PROMOTE EAST NORTHEAST WINDS FOR THE
TERMINALS ON TUESDAY WITH SPEEDS GENERALLY LESS THAN 10
KNOTS...BUT INCREASING TO 10 TO 15 KNOTS TOWARD THE END OF THE
PERIOD. BULK OF PRECIP WITH THIS SYSTEM LIKELY TO OCCUR AFTER THIS
FORECAST VALID PERIOD...ALTHOUGH HAVE INCLUDED -RA INITIALLY AT
KSBN THIS EVENING...TRANSITIONING TO RASN TOWARD THE END OF THE
PERIOD. WILL HOLD OFF ON PRECIP INCLUSION AT KFWA FOR THIS
FORECAST PERIOD...WITH INITIALLY STRONGER MID LEVEL FRONTOGENESIS
FORCING SETTING UP ACROSS FAR NORTHERN INDIANA.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...WINTER STORM WATCH FROM LATE TONIGHT THROUGH WEDNESDAY AFTERNOON
     FOR INZ008-009-013-015>018-020-022>025.

     WINTER STORM WATCH FROM LATE TONIGHT THROUGH WEDNESDAY AFTERNOON
     FOR INZ003>007-012-014.

MI...WINTER STORM WATCH FROM LATE TONIGHT THROUGH WEDNESDAY AFTERNOON
     FOR MIZ077>081.

OH...WINTER STORM WATCH FROM LATE TONIGHT THROUGH WEDNESDAY AFTERNOON
     FOR OHZ004-005-015-016.

     WINTER STORM WATCH FROM LATE TONIGHT THROUGH WEDNESDAY AFTERNOON
     FOR OHZ001-002.

LM...NONE.
&&

$$

SYNOPSIS...MURPHY
SHORT TERM...MURPHY
LONG TERM...MARSILI
AVIATION...MARSILI


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