000
FXUS63 KIWX 072023
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
323 PM EST SAT DEC 7 2013

.SYNOPSIS...
ISSUED AT 322 PM EST SAT DEC 7 2013

CLOUDS WILL DECREASE ACROSS MUCH OF THE REGION TONIGHT AS HIGH
PRESSURE BUILDS ACROSS THE NORTHERN GREAT LAKES.  ANOTHER
DISTURBANCE WILL RACE INTO THE REGION LATE THIS WEEKEND...BRINGING
A PERIOD OF LIGHT SNOW SUNDAY AFTERNOON ALONG WITH A POSSIBILITY
OF SOME FREEZING DRIZZLE SUNDAY NIGHT. LOWS TONIGHT WILL MAINLY BE
IN THE TEENS WITH HIGHS SUNDAY IN THE 20S.

&&

.SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT)
ISSUED AT 319 PM EST SAT DEC 7 2013

QUIET START TO THE PERIOD AS HIGH PRESSURE MOVES OUT OF THE PLAINS
INTO THE NORTHERN GREAT LAKES. THIS WILL ALLOW THE LOW LEVEL FLOW TO
BECOME MORE EAST AND SOUTHEAST WITH TIME AND BRING AN END TO THE
LAKE EFFECT. LAKE EFFECT SNOW SHOWERS HAVE BEEN RAPIDLY
DIMINISHING AND EXPECTING LITTLE MORE THAN SOME LINGERING FLURRIES
INTO EVENING. VERY DRY AIR MASS WILL THEN SETTLE IN THROUGH EARLY
SUNDAY AFTERNOON WITH MOSTLY CLEAR/SUNNY SKIES TO START SUNDAY.

ENERGETIC UPPER FLOW WILL AMPLIFY OVER THE NEXT 24 TO 36 HOURS IN
THE WEST AS SEVERAL PIECES OF ENERGY...EACH ACCOMPANIED BY JET
STREAKS IN EXCESS OF 140 KTS CARVE OUT A DEEP BUT ELONGATED TROUGH.
THIS WILL ALLOW THE FLOW TO BUCKLE NORTHWARD AND A TONGUE OF LOW
LEVEL WARM AIR TO MAKE A RUN AT PORTIONS OF THE CWA. WHILE THE MAIN
BAROCLINIC ZONE WILL REMAIN WELL SE OF THE AREA...285K ISENTROPIC
LIFT ACROSS THE AREA LATE SUNDAY MORNING AND CONTINUE TO STRENGTHEN
WITH NEARLY 40 KTS OF FLOW BY SUNDAY NIGHT. CONDENSATION PRESSURE
DEFICITS DROP BELOW 10 MB ARE MOST WIDESPREAD BETWEEN 21Z SUN AND 6Z
MON. LIGHT PRECIP SHOULD BEGIN TO BREAK OUT BY THIS TIME FRAME AS
DRY (PWAT AROUND 0.2 INCHES) AIR MASS BECOMES SATURATED. WIDESPREAD
LIGHT SNOWFALL WOULD TYPICALLY BE A GOOD BET WITH LIGHT ACCUMS.
HOWEVER...AT THE SAME TIME THAT FULL SATURATION OCCURS ACROSS MOST
LOCATIONS...THE WARM AIR MODIFIES THE PROFILE SUFFICIENTLY TO PUSH
THE DGZ ABOVE THE CLOUD LAYER RESULTING IN THE DEMISE OF ICE CRYSTAL
PRESENCE ACROSS THE SOUTHERN HALF TO THREE QUARTERS OF THE AREA.
THIS WILL LEAD TO INCREASING CHANCES FOR FREEZING DRIZZLE WITH SOME
POTENTIAL FOR LIGHT MEASURABLE PRECIP AND SUBSEQUENT MINOR ICE
ACCUMULATIONS. TRAVEL CONDITIONS COULD BECOME RATHER SLIPPERY FOR
THE MONDAY MORNING COMMUTE. PREV FORECAST WAS GENERALLY HANDLING
EVERYTHING WELL WITH A START OUT OF SOME LIGHT SNOW PRIOR TO THE
WARM AIR ARRIVING AND THEN TRANSITION TO MAINLY FREEZING DRIZZLE. IF
TRENDS CONTINUE...SOME WINTER HEADLINES MAY BE NEEDED FOR PARTS OF
THE AREA LATE SUN AFTERNOON INTO MONDAY MORNING. WILL ISSUE SPS TO
COVER INCREASING CHANCES FOR TRAVEL ISSUES. LOCATIONS ACROSS THE
FAR NORTH MAY BE SPARED THE FREEZING PRECIP BUT COULD SEE BETTER
CHANCES FOR LIGHT SNOW ACCUMULATIONS AS WARMEST AIR REMAINS SOUTH
AND SOUNDINGS SHOW AT LEAST PARTIAL ICE CRYSTAL DEVELOPMENT.

BY IN LARGE...FORECAST WAS IN DECENT SHAPE IN TERMS OF TIMING AND
COVERAGE FOR ONSET AND PEAK OF THE EVENT. HI RES MODELS ARE ALL
SHOWING BEST ISENTROPIC LIFT AND DEEPEST MSTR QUICKLY DEPARTING E/NE
OUT OF THE AREA IN THE 9 TO 12Z WINDOW. HAVE STARTED DOWNWARD TREND
WITH PRECIP ENDING FAR SW AT THIS POINT WITH CONFINEMENT OF HIGHEST
POPS N/NE. A COLD NIGHT WILL BE ON TAP TONIGHT WITH LOWS DROPPING
BACK INTO THE MID TO UPPER TEENS BUT REBOUND SOMEWHAT TO MID AND
MAYBE UPPER 20S COURTESY OF INITIAL SUNSHINE AND SURGE OF WARMER
AIR.

&&

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 319 PM EST SAT DEC 7 2013

LOW PRESSURE WILL MOVE NE FROM THE GRTLKS MONDAY WITH CYCLONIC FLOW
AND CAA IN ITS WAKE. THIS SHOULD RESULT IN MOSTLY CLOUDY SKIES
ACROSS THE CWA IN THE MORNING WITH SOME DECREASE IN CLOUDINESS
MAINLY SW PORTION OF THE CWA IN THE AFTN... MORESO MONDAY NIGHT AS
RIDGE MOVES ACROSS THE AREA. WK LAKE INDUCED INSTABILITY AND
CYCLONIC WESTERLY FLOW SHOULD SUPPORT A FEW SNOW BANDS ACROSS SWRN
MI... LIFTING NORTH MONDAY NIGHT AS WINDS BACK TO SW.

BROAD TROF ALOFT EXPECTED OVER CENTRAL PORTIONS OF CANADA AND NRN
U.S. TUE-WED CONTG BLO NORMAL TEMPS ACROSS THE MIDWEST. A COUPLE OF
WK SHRTWVS MOVG THROUGH THE NW FLOW ALOFT MAY CAUSE SCT LAKE
EFFECT/ENHANCED SNOW SHOWERS... MAINLY OVER SW MI DURING THIS
TIMEFRAME. FLOW ALOFT OVER NRN CONUS EXPECTED TO WEAKEN AND GRDLY
BACK BY THU AS UPR LOW OVER HUDSON BAY SLOWLY FILLS. SFC HIGH
PRESSURE EXPECTED TO MOVE FROM THE PLAINS WED...ACROSS THE MIDWEST
THU... AND TO THE MID-ATLANTIC STATES FRI. THIS SHOULD RESULT IN SCT
LAKE EFFECT SNOW SHOWERS OVER SW MI ENDING BY THU WITH FAIR WX OVER
THE REMAINDER OF THE CWA. RETURN OF SWLY LOW LEVEL FLOW AS THE HIGH
MOVES AWAY FROM THE AREA SHOULD ALLOW TEMPS TO WARM CLOSER TO NORMAL
BY FRI.

SPLIT FLOW EXPECTED TO DEVELOP LATE WEEK OVER THE SWRN CONUS
RESULTING IN A WK BUT MOISTURE LADEN SRN STREAM SHRTWV MOVG E-ENE
ACROSS THE SRN U.S. FRI-SAT. ATTM PRECIP ASSOCIATED WITH THIS LOW
EXPECTED TO STAY SOUTH OF OUR AREA. WK NRN STREAM SHRTWV/CDFNT MOVG
ACROSS THE AREA SAT SHOULD RESULT IN RENEWED CAA AND POTENTIAL FOR
SOME LAKE EFFECT SNOW SHOWERS OVER NW PORTION OF CWA.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1238 PM EST SAT DEC 7 2013

OVERALL COVERAGE AND INTENSITY OF LAKE EFFECT CLOUDS/SNOWSHOWERS HAS
BEEN ON THE WANE SINCE 15Z AND INLAND EXTENSION HAS BEEN CUT IN HALF
OVER THE PAST HOUR. LIGHT SNOW SHOULD QUICKLY END AT KFWA BY 18Z
WITH CLEARING SKIES SO HAVE LEFT ANY MENTION OF SNOW OUT OF TAFS. AT
KSBN...SEVERAL SMALL BANDS WERE ORIENTED NW-SE AND MAY LINGER A BIT
LONGER. WILL MAINTAIN TEMPO MVFR GROUP TO HANDLE THESE THROUGH 19Z
AND EXPECTED IMPROVING CONDITIONS THEREAFTER. ALL QUIET BY 00Z
ACROSS THE AREA AS LOW PRESSURE DEVELOPS AND MOVES NORTHWEST OF THE
AREA SUNDAY AND SUNDAY NIGHT. OVERRUNNING MSTR WILL ARRIVE LATE
AM/EARLY PM SUNDAY BUT MASSIVELY DRY AIRMASS WILL EAT UP MUCH OF THE
ARRIVING LOW/MID LEVEL MSTR IN SATURATION. MAIN FOCUS OF CONCERNS
WITH REGARDS TO SNOW/FREEZING DRIZZLE POTENTIAL WILL EXIST AFTER 18Z
AND ESPECIALLY IN THE 3Z TO 12Z WINDOW MONDAY WHEN THE POSSIBILITY
EXISTS FOR SOME LIGHT ICING PROBLEMS ON LOCAL RUNWAYS. MORE DETAILS
TO COME ON THIS IN LATER FORECASTS.


&&

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

&&

$$

SYNOPSIS...FISHER
SHORT TERM...FISHER
LONG TERM...JT
AVIATION...FISHER


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