National Weather Service Weather Forecast Office

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FXUS63 KIWX 112338
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
638 PM EST WED DEC 11 2013

.SYNOPSIS...
ISSUED AT 626 PM EST WED DEC 11 2013

SNOW SHOWERS WILL CONTINUE TO DIMINISH ACROSS THE MAJORITY OF THE
AREA THIS EVENING...ALTHOUGH LIGHT LAKE EFFECT SNOW SHOWERS WILL
LINGER INTO TONIGHT. LOWS TONIGHT WILL FALL BELOW ZERO WHERE SKIES
CLEAR...OTHERWISE TEMPERATURES SHOULD BE IN THE SINGLE DIGITS
ABOVE ZERO. WIND CHILL VALUES BELOW ZERO ARE EXPECTED EVERYWHERE.
THURSDAY WILL BE ANOTHER COLD DAY WITH HIGHS IN THE MID TEENS TO
AROUND 20 DEGREES.

&&

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 359 PM EST WED DEC 11 2013

COLD ADVECTION WITHIN VEERED FLOW IN WAKE OF AN ARCTIC FRONT WILL
KEEP SCATTERED LAKE EFFECT SNOW SHOWERS GOING ACROSS MAINLY FAR
NORTH-CENTRAL INDIANA AND SW LOWER MICHIGAN THIS EVENING. THERMAL
PARAMETERS BELOW MODEST INVERSION NEAR 6-7 KFT APPEAR FAVORABLE FOR
DECENT DENDRITIC ICE CRYSTAL GROWTH. HOWEVER...STRONG DRY ADVECTION
WITH LAKE MODIFIED SPECIFIC HUMIDITY IN 1000-850 MB LAYER ONLY 1
G/KG (WITH UPSTREAM SFC DEWPOINTS INTO THE SINGLE DIGITS AND TEENS
BELOW ZERO) SHOULD OFFSET THIS...LIMITING ADDITIONAL ACCUMS TO LESS
THAN AN INCH FOR MOST LOCATIONS (LOCALIZED 1-3 INCH AMOUNTS POSSIBLE
IN SW LOWER MI). EXPECT A CLEARING TREND ELSEWHERE INTO THIS EVENING
PER INCREASE IN COLD/DRY ADVECTION WITHIN DEEPENING NW FLOW. BULK OF
SNOW SHOWER ACTIVITY WILL LIFT NORTH OF THE AREA LATER
TONIGHT/THURSDAY AS FLOW BACKS IN RESPONSE TO SFC HIGH SLIDING SOUTH
OF THE AREA UNDER SIGNIFICANT HEIGHT RISES/LARGE SCALE SUBSIDENCE.

THE MAIN STORY TONIGHT/TOMORROW WILL BE THE COLD TEMPERATURES AND
WIND CHILLS. DROPPED LOWS CLOSER TO COOLER MOS GUIDANCE ACROSS THE
SOUTH AND WEST GIVEN EXPECTATIONS FOR A PERIOD OF MAINLY CLEAR SKIES
WITH FRESH SNOW COVER AND PARTIAL DECOUPLING. WIND CHILLS MAY
APPROACH ADVISORY CRITERIA FOR A FEW AREAS BY LATER TONIGHT IN THE
WEST. LAKE CLOUDS WILL LIKELY LIMIT LONGWAVE LOSS ACROSS THE FAR NORTH
WHERE WARMER MINS ARE ANTICIPATED. WARM ADVECTION ALOFT KICKS IN
LATER TONIGHT INTO TOMORROW WITH 850 MB TEMPS EXPECTED TO RISE
NEARLY 10C TOMORROW. UNFORTUNATELY...ASSOCIATED STRENGTHENING
SOUTHWEST WINDS AND LOW LEVEL INVERSION WILL ONLY ALLOW WIND CHILLS
TO RECOVER INTO THE SINGLE DIGITS ABOVE ZERO BY TOMORROW AFTERNOON.

&&

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 359 PM EST WED DEC 11 2013

...ACCUMULATING SNOW INCREASINGLY LIKELY FRI NIGHT-SAT...

SERIES OF PV ANOMALIES IN THE EASTERN PACIFIC WILL DIVE INTO THE
WESTERN CONUS THURSDAY INTO THURSDAY NIGHT AND EJECT TOWARDS OUR
AREA BY FRIDAY NIGHT. MODELS HAVE BEEN CONSISTENT IN KEEPING THESE
IMPULSES SEPARATE AND SHEARING THEM OUT AS THE PERSISTENT CONFLUENT
FLOW ACROSS THE EASTERN CONUS ELIMINATES THE CHANCE FOR ANY
SIGNIFICANT CYCLONE DEVELOPMENT. SHOULD GET BETTER SAMPLING OF THESE
WAVES BY TOMORROW EVENING AS THEY MOVE INTO THE CONUS...BUT WITH
FAIRLY DECENT MODEL CONSENSUS ATTM...EXPECT LITTLE DEVIATION FROM
THE CURRENT SW TRACK THROUGH THE SE PORTION OF THE CWA. DESPITE A
SHEARED OUT/WEAKENING SYSTEM MOVING TOWARDS OUR AREA...A SOLID 2 TO
3 INCH SNOWFALL ACROSS OUR NW HALF AND 3 TO 5 INCH SNOW ACROSS THE
SE HALF IS LOOKING INCREASINGLY LIKELY.

WEAK ISENTROPIC LIFT ALONG THE THERMAL GRADIENT ACROSS THE STATE
WILL SPEND MOST OF THE TIME FRIDAY SATURATING THE COLUMN. EXPECT
SNOWFALL TO COMMENCE AFTER 00Z AS THE DEEPER MOISTURE ARRIVES ON
FRIDAY NIGHT AHEAD OF THE MID LEVEL SW AS IT EJECTS INTO THE OZARK
PLATEAU. WHILE THERE IS NO INDIVIDUAL FORCING THAT IS EXCESSIVELY
STRONG...COMBINATION OF ISENTROPIC LIFT...DCVA...AND 925-700 MB
FRONTOGENESIS WILL LEAD TO A SOMEWHAT LONG DURATION (15-18 HR)
MODERATE SNOWFALL PERIOD. SOME MESOBANDING CONCERNS AS BEST OMEGA
ALIGNS WELL WITH THE LOW/MID LEVEL FRONTOGENESIS AND THE DGZ AS WELL
AS AT LEAST NEAR NEUTRAL EPV DIRECTLY ABOVE. THESE AREAS OF
MESOBANDING WILL NEED TO BE WATCHED FOR POTENTIALLY HIGHER
ACCUMULATION AMOUNTS. EXPECT HEAVIEST SNOWFALL TO BE ALONG AND
SOUTHEAST OF US 24 FROM AROUND 03Z SATURDAY THROUGH 21Z SATURDAY.

RESIDUAL LOW LEVEL SYNOPTIC MOISTURE BEHIND THIS SYSTEM AND
CONTINUED CYCLONIC FLOW WILL KEEP THE CHANCE FOR LIGHT SNOW SHOWERS
ACROSS MOST OF THE CWA ON SUNDAY WITH THE BEST CHANCES DOWNSTREAM OF
THE LAKE. LIGHT WINDS WILL INCREASE PARCEL RESIDENCE TIME OVER THE
LAKE...BUT LOWERING INVERSION HEIGHTS AND DRY MID LEVEL AIR WILL
INHIBIT MUCH IN THE WAY OF SNOWFALL ACCUMULATIONS.

A FEW WEAK CLIPPER SYSTEMS WILL PARADE TOWARDS THE GREAT LAKES FOR
THE FIRST PART OF THE WEEK. THE FIRST OF THESE SYSTEMS WILL PASS BY
TO THE NORTH OF OUR AREA SOMETIME MONDAY WITH A MORE SIGNIFICANT
WAVE TO PASS THROUGH THE AREA SOMETIME TUESDAY. THE IMPACT OF THESE
WAVES ON OUR FORECAST AREA WILL REMAIN UNCERTAIN UNTIL THE FRIDAY
NIGHT/SATURDAY SYSTEM MOVES THROUGH AND MODELS BETTER RESOLVE THE
EXACT PLACEMENT OF THE LONGWAVE TROUGH.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 626 PM EST WED DEC 11 2013

LIGHT LAKE EFFECT SNOW SHOWERS WILL SLOWLY DIMINISH TONIGHT AS
INVERSION LOWERS AND WINDS BACK TO SW WITH RIDGE PASSAGE. IN THE
MEANTIME EXPECT MVFR CONDITIONS TO PERSIST AT SBN WITH LOW VFR AT
FWA. VFR CONDITIONS SHOULD PREVAIL THU WITH A PERIOD OF
STRATO/ALTO CU IN THE MORNING AS A TROF PRECEDED BY FAIRLY STRONG
WAA MOVES ACROSS THE AREA.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 7 PM EST THURSDAY FOR LMZ043-046.

&&

$$

SYNOPSIS...CEO
SHORT TERM...STEINWEDEL
LONG TERM...BENTLEY
AVIATION...JT


VISIT US AT WWW.WEATHER.GOV/IWX (ALL LOWER CASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.NORTHERNIN.GOV
WWW.TWITTER.COM/NWSIWX
WWW.YOUTUBE.COM/NWSNORTHERNINDIANA