Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 290003
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
803 PM EDT TUE OCT 28 2014

.SYNOPSIS...
ISSUED AT 750 PM EDT TUE OCT 28 2014

COOL AND MAINLY DRY CONDITIONS ARE EXPECTED THROUGH MIDWEEK...
WITH ONLY SOME SCATTERED SPRINKLES POSSIBLE WEDNESDAY ACROSS
LOWER MICHIGAN. LOW TEMPERATURES TONIGHT WILL RANGE FROM THE
UPPER 30S TO LOWER 40S. HIGH TEMPERATURES ON WEDNESDAY WILL RANGE
FROM THE UPPER 40S TO LOWER 50S.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 350 PM EDT TUE OCT 28 2014

COLD FRONT HAS EXITED NORTHWEST OHIO THIS AFTERNOON WITH POST
FRONTAL COLD ADVECTION CONTINUING THROUGH TONIGHT. INITIAL UPPER
LEVEL TROUGH ACROSS THE WESTERN GREAT LAKES WILL BEGIN TO SHIFT
NORTHEAST TONIGHT...WITH ONLY A GLANCING BLOW OF STRONGER
MID/UPPER LEVEL COLD POOL ACROSS THE SOUTHERN GREAT LAKES.
STRATOCU HAS FILLED IN SOMEWHAT ACROSS SOUTHERN WISCONSIN AND SCT-
BKN LOW CLOUDS MAY SHIFT ACROSS FAR NORTHERN PORTIONS OF THE AREA
THIS EVENING. HOWEVER...WITH COLD POOL ALOFT BEGINNING TO LIFT
SLIGHTLY NORTHEAST TONIGHT AND LOSS OF DAYTIME HEATING...SHOULD
TEND TO SEE THESE LOW CLOUDS DIMINISH AT LEAST EARLY THIS EVENING.
BY LATE TONIGHT...SECONDARY UPPER TROUGH WILL ROUND LARGE SCALE
UPPER CIRCULATION...PROVIDING REINFORCING LOW/MID LEVEL CAA.
PASSAGE OF THIS UPPER TROUGH LATE TONIGHT SHOULD ALLOW A MORE
SOLID STRATOCU DECK TO MOVE ACROSS AT LEAST NORTHERN THIRD OF THE
AREA. IN TERMS OF TEMPERATURES...LOW LEVELS WILL REMAIN WELL MIXED
TONIGHT WHICH SHOULD PREVENT A SIGNIFICANT DROP OFF. HOWEVER...THE
MAGNITUDE OF AIR MASS ADVECTING INTO THE AREA SHOULD SUPPORT LOWS
FROM UPPER 30S TO LOWER 40S...AND PERHAPS LOWER TO MID 40S IN
VICINITY OF LAKE MICHIGAN SHORELINE.

A QUIET DAY IS IN STORE FOR WEDNESDAY...WITH AFOREMENTIONED
SECONDARY TROUGH THE MAIN FEATURE OF INTEREST AS IT SWINGS ACROSS
THE GREAT LAKES REGION. MAINTENANCE OF CYCLONIC FLOW/STEEP LOW LEVEL
LAPSE RATES SHOULD SUPPORT BROKEN-OVERCAST STRATOCU DECK ACROSS THE
NORTH...ESPECIALLY FROM MID MORNING THROUGH MID AFTERNOON. LAKE
INDUCED INSTABILITY IS EXPECTED TO BE QUITE SHALLOW...BUT COULD BE
SUFFICIENT FOR A FEW SCATTERED LIGHT RAIN SHOWERS OR SPRINKLES WITH
WEAK BACKGROUND SYNOPTIC FORCING. IF SOLID LOW CLOUD DECK DOES
BECOME ESTABLISHED ACROSS THE NORTH...HIGHS MAY STRUGGLE TO REACH 50
AND NOT MUCH CHANGE MADE TO PREVIOUS FORECAST AT THIS TIME. GOOD LOW
LEVEL MIXING WILL SUPPORT GUSTS TO AROUND 20 MPH AGAIN ON
WEDNESDAY...ALTHOUGH SLACKENING GRADIENT IN THE AFTERNOON SHOULD
RESULT IN RAPID DECOUPLING TOWARD EVENING.

&&

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 350 PM EDT TUE OCT 28 2014

NO MAJOR WEATHER CONCERNS TO START THE PERIOD OFF WITH WEAK SFC HIGH
PRESSURE SET TO DRIFT SOUTH OF THE FORECAST AREA WITH PERSISTENT NW
FLOW ALOFT KEEPING TEMPERATURES SEASONABLY WARM (MID 50S THURSDAY).
MAIN FOCUS REMAINS APPROACH OF STRENGTHENING UPPER LEVEL SYSTEM
WHICH WAS OVER WESTERN CANADA (PARTIALLY MADE UP OF REMNANTS OF
TROPICAL SYSTEM ANA). A WEAK SHORT WAVE WILL DROP RAPIDLY SOUTHEAST
TOWARDS THE REGION THURSDAY NIGHT WITH AN OUTSIDE CHANCE FOR SOME
LIGHT SHOWERS BUT MORE AN INCREASE IN CLOUDS. ECMWF/GEM ARE THE MOST
AGGRESSIVE/DEEP WITH THE MAIN UPPER LOW TRACKING IT FROM WEST OF
HUDSON BAY WEDNESDAY EVENING WEST OF LAKE SUPERIOR (STILL AN OPEN
WAVE) TO VICINITY OF SOUTHERN LAKE MI BY FRIDAY AFTERNOON. ECMWF
SUGGESTS TEMPERATURE PROFILES WOULD LEND MORE CREDENCE TO
INTRODUCING MENTION OF SNOW IN NE AREAS FRIDAY AFTERNOON WITH
1000-850 MB THICKNESS VALUES. SFC TEMPERATURES WILL STILL BE
CRITICAL WITH READINGS AROUND 40 OR LOWER 40S EARLY. DO EXPECT
FALLING TEMPS IN THE AFTERNOON BUT DEEPEST MOISTURE QUICKLY DEPARTS
AT THE SAME TIME. HAVE INCREASED POPS TO LIKELY IN NE AREAS GIVEN
LAKE ENHANCEMENT AND STRENGTH OF FEATURES.

MODELS TRENDING TOWARDS FEATURES SLOWING DOWN FRIDAY NIGHT AS UPPER
LOW WRAPS UP AND DEEPENS FURTHER. THUS AN INTRODUCTION IN POPS IN
EASTERN AREAS IS WARRANTED (CHC). IN TERMS OF LAKE EFFECT...FLOW
WILL QUICKLY BECOME NORTH OR NNW WHICH WILL KEEP MAJORITY OF THE
ACTIVITY JUST TO THE WEST OF THE AREA INTO WESTERN PARTS OF LAPORTE
STARKE AND PULASKI COUNTIES. GIVEN TEMPERATURES IN THE 20S AND
30S...HAVE WENT ALL SNOW FRI NGT.

MUCH LIKE THE LAST SYSTEM THE MAIN UPPER LOW WILL DROP INTO THE
CAROLINAS BY SATURDAY AFTERNOON WITH A A STRONG NE FLOW ACROSS
MAINLY EASTERN AREAS TO POSSIBLY MAKE FOR A BLUSTERY DAY SATURDAY.
ENERGY WILL PHASE WITH WEAKER WAVE ALONG THE EAST COAST AND RAPIDLY
DEEPEN AS IT HEADS UP THE COAST. HIGH PRESSURE WILL DRIFT ACROSS THE
AREA WITH OVERNIGHT LOWS FRI AND SAT NGT BELOW FREEZING IN MOST
LOCATIONS AND HIGHS STRUGGLING TO CLIMB INTO THE 40S SATURDAY. SOME
MODERATION BEGINS TOWARDS THE END OF THE PERIOD AS THE HIGH DEPARTS.
ANOTHER DEEP LOW PRESSURE AREA WILL TAKE SHAPE...BUT THIS TIME MUCH
FURTHER NORTH IN SOUTHERN CANADA. A FRONT WILL BE DRIVEN INTO THE
AREA WITH SOME RETURN IN MOISTURE EXPECTED. SUPERBLEND OF GUIDANCE
WANTS TO PLACE LIKELY POPS IN THIS PERIOD BUT WITH AREA SO REMOVED
FROM MAIN DYNAMICS THIS IS TOO PREMATURE AT THIS POINT TO GO THAT
HIGH. HAVE WENT CHC POPS MON NGT INTO TUES.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 800 PM EDT TUE OCT 28 2014

UPSTREAM SHORTWAVE ACROSS NWRN GREAT LAKES /YOOP INTO NRN MN/ TO
ROTATE THROUGH WESTERN GREAT LAKES WED AM AS PRIMARY VORTEX LIFTS
OUT INTO WESTERN QUEBEC. SECONDARY LOW LEVEL COLD AIR ADVECTION
PUSH WED AM...ALONG WITH CYCLONIC LOW LEVEL 925-850MB LAYER
FLOW...APPEARS SIGNIFICANT ENOUGH TO SUPPORT HIGH END MVFR BKN
STRATOCU DECK ACROSS NRN IN...IN LINE WITH LATEST 4KM NAM BUFKIT
PROFILES. IRREGARDLESS...CONDITIONS SHOULD NOT DETERIORATE BELOW
FUELING/ALTERNATE LEVELS AND SHALLOW MOMENTUM TRANSFER SHOULD
KEEP DAYTIME GUSTS GENERALLY AOB 20KTS.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 3 PM EDT WEDNESDAY FOR LMZ043-046.

&&

$$

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


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