Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 272047
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
347 PM EST SAT DEC 27 2014

.SYNOPSIS...
ISSUED AT 332 PM EST SAT DEC 27 2014

LOW PRESSURE OVER SOUTHERN ONTARIO WILL CONTINUE ITS NORTHEASTWARD
PATH OVERNIGHT. AS A RESULT...RAIN SHOWERS AND DRIZZLE ACROSS THE
FORECAST AREA WILL DWINDLE. SOME OF THESE RAIN SHOWERS MAY MIX WITH
SNOW LATER TONIGHT IN THE SOUTHEAST. OTHERWISE...HIGH PRESSURE WILL
MOVE IN FOR SUNDAY. AS A RESULT...SKIES ON SUNDAY WILL BE PARTLY TO
MOSTLY CLOUDY IN THE SOUTHEAST...AND MOSTLY SUNNY IN THE NORTHWEST.
LOWS TONIGHT WILL BE IN THE UPPER 20S AND LOW TO MID 30S. HIGHS
SUNDAY WILL BE IN THE MID TO UPPER 30S.

&&

.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 346 PM EST SAT DEC 27 2014

THE COLD FRONT WAS JUST ENTERING THE FAR NORTHWEST CORNER OF THE
FORECAST AREA FROM NEAR BENTON HARBOR TO LAPORTE INDIANA AT 3 PM EST.
BRIEF SUSTAINED WINDS AROUND 30 MPH WITH ISOLATED GUSTS TO 45 MPH
ARE POSSIBLE FOR THE FIRST HOUR OR TWO BEHIND THE FRONT. WEAK LIFT
ON THE 295K SFC WAS STILL ENOUGH TO SUPPORT LIGHT PRECIPITATION SO
LIGHT SHOWERS ARE ALSO POSSIBLE BEHIND THE FRONT ALONG WITH A BRIEF
MIX OF SNOW BEFORE THE PRECIPITATION ENDS. NO SNOW ACCUMULATION IS
EXPECTED.

&&

.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 332 PM EST SAT DEC 27 2014

...MAIN FOCUS OF THE LONG TERM IS LAKE EFFECT SNOW MONDAY AFTERNOON
INTO WEDNESDAY AND THE LOW PRESSURE SYSTEM EXPECTED TO MOVE INTO THE
GREAT LAKES REGION NEXT WEEKEND...

500MB LOW SITUATED OVER QUEBEC WILL KEEP A BROAD TROUGH OVER THE
GREAT LAKES REGION THROUGH WEDNESDAY NIGHT AS A RIDGE OVER THE
SOUTHEASTERN UNITED STATES DRIFTS INTO THE ATLANTIC. THIS KEEPS THE
CWA SUSCEPTIBLE TO PASSING SHORTWAVES. MEANWHILE...A CUT OFF LOW
SWINGS OVER CALIFORNIA WEDNESDAY AFTERNOON AND DRIFTS EASTWARD
SOMEWHERE INTO THE CENTRAL PLAINS BY FRIDAY NIGHT/DEPENDING ON THE
MODEL/. ANOTHER RIDGE WILL BUILD AHEAD OF THIS CUT OFF LOW...FURTHER
AMPLIFYING THE PATTERN AND SETTING THE STAGE FOR THE NEXT POTENTIAL
WEATHER-MAKER OVER THE FORECAST AREA. MODELS MERGE THE CUT OFF LOW
AND THE TROUGH ASSOCIATED WITH THE QUEBEC LOW BY 00Z SUNDAY...THOUGH
TIMING AND LOCATION OF THIS MERGE VARY DEPENDING ON THE MODEL USED.

AT THE SURFACE HIGH PRESSURE OVER THE CANADIAN PRAIRIE EXPANDS INTO
THE GREAT LAKES REGION THROUGH THURSDAY NIGHT. AS THE HIGH SINKS
SOUTHEASTWARD INTO THE CENTRAL PLAINS FRIDAY...LOW PRESSURE OVER
HUDSON BAY BRINGS A TROUGH ACROSS MICHIGAN. DEPENDING ON THE
MODEL...LOW PRESSURE ASSOCIATED WITH THE PHASING ENERGY ALOFT WILL
PASS THROUGH THE GREAT LAKES REGION. EXACT PATH AND STRENGTH OF THE
SYSTEM VARIES GREATLY AMONG THE MODELS.

FORECAST WISE...THIS SFC PATTERN ALLOWS COLD ARCTIC AIR TO
INFILTRATE THE GREAT LAKES...WITH 850MB TEMPS DIPPING TO -16C OVER
SOUTHERN LAKE MI BY WEDNESDAY. HIGHS WILL START OUT NEAR NORMAL
MONDAY...THEN DROP BELOW NORMAL INTO THE 20S AND MAYBE EVEN THE
TEENS BY WEDNESDAY. LOWERED TEMPERATURES FROM THE CONSENSUS BLEND IN
THE EXTENDED AS A RESULT.

WITH ARCTIC AIR PLUNGING INTO THE GREAT LAKES...LAKE EFFECT SNOW
WILL BE THE PRIMARY FOCUS MONDAY INTO TUESDAY NIGHT. A COLD FRONT
WILL SINK ACROSS LAKE MICHIGAN LATE SUNDAY NIGHT INTO MONDAY
MORNING...BRINGING AN UPTICK IN MOISTURE. 1000-700 MB TDD`S DECREASE
TO 1-3C BY MONDAY MORNING AS THE FRONT APPROACHES...AND REMAIN THAT
WAY UNTIL DRIER AIR BEHIND THE FRONT SLOWLY ARRIVES LATE TUESDAY
AFTERNOON/EVENING. 700MB DELTA TS INCREASE INTO THE 20-22C RANGE BY
MONDAY NIGHT...AND THETA E LAPSE RATES DROP FROM -3 TO -5...WHICH IS
ENOUGH INSTABILITY TO KICK OFF AND SUSTAIN THE LAKE EFFECT NEAR LAKE
MICHIGAN. ADDITIONALLY...WITH PASSING SHORTWAVES IN THE CYCLONIC
FLOW ALOFT...INVERSION HEIGHTS THROUGH THE MONDAY EVENING INTO
TUESDAY AFTERNOON PERIOD LIFT TO NEAR 700MB AT TIMES. WHILE THINGS
LOOK MORE SUPPORTIVE OF LIGHT TO MODERATE LAKE EFFECT SNOW...THE
WIND DIRECTIONS CHANGE FAIRLY QUICKLY TO MOVE THE BAND THROUGHOUT
THE PERIOD.

AS FAR AS THE LOCATION OF THE SNOW...WINDS BECOME NORTHERLY BEHIND
THE COLD FRONT MONDAY MORNING...THEN BECOME MORE NORTHEASTERLY
THROUGH MONDAY EVENING. AS THE ARCTIC SURFACE HIGH EXPANDS EASTWARD
AND STRONGER WINDS OVER WI BECOME MORE NORTHERLY...NORTHEAST
FLOW/LAND BREEZES OVER MI INCREASE MOISTURE CONVERGENCE OVER LAKE MI
AND DEVELOP A BAND. BOTH THE GFS/GEM/NAM HAVE THE BAND ORIENTED
NORTH-SOUTH BY 12Z TUESDAY...DROPPING INTO PORTER IN/LAKE IL
COUNTIES...AND CLIPPING WESTERN LAPORTE. BY 15Z HOWEVER WINDS BECOME
NORTHWESTERLY AS THE 500MB SHORTWAVE SWINGS SOUTH OF THE
AREA...WHICH SHIFTS THE BAND INTO SOUTH BEND BY 18Z. MOISTURE
QUICKLY DWINDLES AROUND THIS TIME FRAME HOWEVER...AND WINDS BECOME
WESTERLY BY EARLY TUESDAY EVENING. THINKING A BRIEF SPURT OF LIGHT
TO MODERATE SNOW IS THE MOST LIKELY OUTCOME UNTIL THEN...THOUGH
STILL EXPECTING OVERALL LIGHT ACCUMULATIONS AS THE BAND DRIFTS
AROUND INSTEAD OF STAYING STATIONARY AND BECAUSE MOISTURE BECOMES SO
LIMITED. HAVE AN INCH OR LESS IN THE GRIDS FOR NOW...CONFINED TO THE
LAKE MI SHORE.

WEDNESDAY AND THURSDAY LOOK TO BE QUIETER...WITH LIGHT WEST TO
SOUTHWESTERLY FETCH LAKE EFFECT SNOW SHOWERS. WOULD NOT BE SURPRISED
IF THESE DIDNT MATERIALIZE...AS MOISTURE IS LACKING. THE BRIEF
EXCEPTION IS A QUICK INCREASE IN MOISTURE AHEAD OF ANOTHER SHORTWAVE
ON WEDNESDAY MORNING...MAINLY TO THE NORTH OF THE CWA. KEPT GOING
SLIGHT CHANCE POPS IN WSW WIND FAVORED REGIONS.

FRIDAY INTO SATURDAY OUR ATTENTION TURNS TO THE LOW PRESSURE SYSTEM
EXPECTED TO IMPACT THE REGION. AS USUAL...MODELS ARE HAVING QUITE A
BIT OF DIFFICULTY HANDLING THE SITUATION. THE ECMWF SLOWS THE TIMING
DOWN...BRINGING THE SURFACE LOW INTO THE OHIO VALLEY BY 00Z SUN. THE
PROGRESSIVE GFS PULLS THE LOW INTO SOUTHEASTERN LOWER MI BY 12Z
SATURDAY. KEPT CONSENSUS POPS IN THE FORECAST FOR NOW GIVEN THE
SIGNIFICANTLY DIFFERENT SOLUTIONS. FOR NOW KEPT P-TYPE ALL SNOW WITH
THE EXCEPTION OF THE FAR SOUTHEAST...WHERE TEMPS ARE SLIGHTLY ABOVE
FREEZING.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 203 PM EST SAT DEC 27 2014

AREAS OF DRIZZLE AND LOWS CLOUDS WILL PERSIST AHEAD OF A COLD
FRONT UNTIL THE FRONT PASSES LATE THIS AFTERNOON/EARLY THIS
EVENING. IFR CIGS EARLY SHOULD BECOME VFR BY LATE IN THE PERIOD AS
DRIER AIR SPREADS INTO NORTHERN INDIANA. THE FRONT PASSED GARY
ABOUT 17Z AND SHOULD BE ACCOMPANIED BY BRIEFLY HIGHER SUSTAINED
WINDS AND WIND GUSTS.


&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 11 AM EST SUNDAY FOR LMZ043-046.

&&

$$

SYNOPSIS...MCD
SHORT TERM...SKIPPER
LONG TERM...MCD
AVIATION...SKIPPER


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