Blizzard in Michigan, December 21 to 22, 2008

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
406 AM EST SUN DEC 21 2008

.SHORT TERM...
TODAY THROUGH MONDAY NIGHT.

...BITTER WIND CHILLS...LAKE EFFECT SNOWSHOWERS AND INCREASING
THREAT FOR POWER OUTAGES CONTINUE TO LOOM...

ARCTIC COLD FRONT MAKING GOOD PROGRESS WITH TEMPS PLUMMETING BEHIND
IT. MOST LOCATIONS GOING FROM MIDDLE 20S TO THE SINGLE DIGITS WITHIN
3 HOURS. ALSO BURST OF STRONGER WIND GUSTS ASSOCIATED WITH THE STG
CAA WITH GUSTS IN THE 30 TO 35 KT RANGE. HAS BEEN SOME DISCUSSION ON
WIND ADVISORIES FROM SURROUNDING OFFICES...BUT THINK FOR NOW WILL
HOLD OFF ON ANYTHING. IF WE CAN GET SOME SUN THIS AFTERNOON AND
ALLOW FOR SOME MIXING...COULD BE LOOKING AT THE NEED FOR ONE FOR THE
AFTERNOON AND EVE HOURS. WILL DEFER TO DAY SHIFT TO MONITOR.

HAVE LOWERED HIGHS TODAY TO BETTER REFLECT THE PUSH OF COLD AIR.
STARTING AT 12Z ANTICIPATING TEMPS TO BE WELL INTO THE SINGLE DIGITS
WEST TO MID TEENS EAST AS FRONT WILL JUST BE CLEARING THESE AREAS.
THEN TEMPS WILL CONTINUE TO SLOWLY FALL. POPULATED WITH RUC40 DATA
WHICH SEEMS TO HAVE A GOOD HANDLE ON TRENDS...WHICH WOULD PUT SOME
LOCATIONS IN THE SW AREAS NEAR OR EVEN BELOW ZERO BY LATE MORNING.
GIVEN UPSTREAM TEMPS ALREADY 1 ABOVE AT ORD AND CORE OF COLDEST 850
MB TEMPS POISED TO PASS OVER THE SW HALF THIS AFTERNOON WITH VALUES
IN THE -25 TO -28 C RANGE /15 TO 20 DEGREES BELOW MEANS FOR
DECEMBER/...THINK THIS IS REASONABLE AND GRIDS REFLECT THIS. THIS
BRINGS ANOTHER CHALLENGE. IF WINDS DO REMAIN UP...THEN THESE SAME
AREAS WILL APPROACH OR EXCEED WIND CHILL WARNING CRITERIA. FOR NOW
WILL STICK WITH ADVISORY...BUT SPEED UP ONSET TO START WITH PACKAGE
RELEASE AND LET DAY SHIFT MONITOR WINDS AND TEMPS FOR POSSIBLE
UPGRADE.

ALSO HAS HAS BEEN NOTED IN MANY PRODUCTS...ANTICIPATING INCREASED
ISSUES WITH POWER OUTAGES AND TREE/POWER LINE DAMAGE AS STRONG WINDS
OVERLOAD ALREADY BURDENED LINES AND TREES. POWER HAS ALREADY BEEN
FLUCTUATING HERE AT THE OFFICE AND EXPECT THIS TO CONTINUE FOR MANY
AREAS WITH ICE STILL AROUND.

LAKE EFFECT SNOWSHOWERS WILL QUICKLY KICK IN BEHIND THE FRONT WITH
THE BULK OF THE ACTIVITY ACROSS THE FAR NORTHERN PARTS OF THE AREA.
WILL CONTINUE WITH WINTER STORM WARNING FOR BERRIEN THROUGH ST JOE
COUNTIES IN MICHIGAN. WHILE BEING A BIT OF A PROLONGED EVENT...WIND
CHILLS...WINDS...TEMPS AND SNOWFALL WILL ALL LEAD TO ROUGH TRAVEL IN
THESE AREAS. BAND STILL LOOKS TO SET UP RATHER NICELY TOWARDS MONDAY
MORNING ACROSS THE FAR SOUTHER MICHIGAN COUNTIES AND SINCE THIS HAS
BEEN THERE FOR SEVERAL RUNS WILL BLEND WITH GRR AND DTX AND EXPAND
LIKELY POPS OUT INTO HILLSDALE CO. WILL KEEP AMOUNTS IN THE 1 TO 2
INCH RANGE IN THESE AREAS FOR NOW.

THINGS LOOK TO EASE UP FOR MONDAY AND MONDAY NIGHT TO GIVE A DRY BUT
COLD FORECAST BEFORE THE NEXT SYSTEM ARRIVES IN THE LONG TERM.

&&

.LONG TERM...
DIFFICULT FCST PD THROUGHOUT.

VRY INTENSE SW TROUGH OVR THE GULF OF AK YDA HAS STEAMED SEWD TO NR
COASTAL WA STATE THIS MORNING...BRINGING RARE HEAVY SNOW TO KSEA AND
A GOOD INDICATOR OF HOW INTENSE THIS SYS IS. UPSTREAM JET STREAK PER VAPOR
LOOKS QUITE INTENSE AS WELL AND WILL AID SYS DIG INTO SWRN ROCKIES
TUE. DOWNSTREAM CONDS REMAIN A MESS THOUGH W/INCOMING INTENSE ARCTIC
WEDGE AND EVENTUALLY STG LL MSTR RTN OVERTOP RETREATING COLD DOME
MID WEEK. 00Z GUIDANCE TAKEN AS A WHOLE TRENDING QUICKER W/PCPN DVLPMNT
AND NOW INDICATING SNOW TUE AM AND SEE NO REASON TO ARGUE GIVEN UPR
JET SHIFTING THROUGH THE NRN LAKES BY TUE AFTN. PRIMARY DIFFICULTY
LIES W/LL THERMAL RESPONSE INTO RETREATING ARCTIC WEDGE. AS NOTED
YDA...STILL FEEL MODELS ERODING ARCTIC DOME TOO QUICKLY ESP OVR
DEEPER HIGH DENSITY SNOWPACK ACRS NRN PORTION OF CWA YET ON THE
OTHER HAND CANT DISCOUNT LACK OF SNOW CVR ACRS DOWNSTATE IL/IN.
THUS IT SEEMS AT LEAST THE THREAT FOR ANOTHER POTENTIALLY SIG ICING
EVENT PSBL TUE NIGHT AND WED ACRS NRN/NW THIRD OF CWA. PRIOR TO
THAT...MAINLY SNOW TUE INTO TUE EVENING BFR WARM LYR LEADS TO IP MIX
GENERALLY SOUTH OF US 30 AND ZR SOUTH OF US 24.

EJECTION OF INTENSE WRN SW LT TUE MORE DISCONCERTING GIVEN DRAMATIC
MED RANGE TRENDS W/DEGREE OF SFC DVLPMNT SEEN IN 00Z GFS AND ITS
ENSEMBLES. OP GFS/ECMWF SOLUTIONS SIMILAR...BOTH IN INTENSITY AND
QUICKER NEWD EJECTION COMPARED W/GFS ENSEMBLES YET CERTAINLY WITHIN
THE SCOPE OF POSSIBILITIES. PRIOR FLAT OPEN WV EJECTION SEEN IN 12Z
RUNS COMPARABLE W/LATEST WRF 4KM RUN SO UNCERTAINTY IS HIGH. BEST
RECOURSE AT THIS POINT IS TO WEIGHT WED PD MORE HEAVILY TWD A MIXED
PCPN EVENT XPC PERHAPS FAR NW PER IMPLIED SFC LOW TRACK BUT DO XPC
ADDNL SIG FLUCTUATIONS THROUGH THE NXT 36HRS UNTIL THIS SYS GETS
FURTHER INTO UPR AIR NETWORK AND SAMPLED BTR. IN THE LEAST...ANOTHER
HEAVY PRECIPITATION EVENT LIKELY TO BE REALIZED TUE NIGHT/WED.

AFT THAT...PATTN RELOADS AMAZINGLY FAST W/YET ANOTHER INTENSE MID
LAT CYCLONE FOR LT WEEK. ADDNL HEADACHES CERTAIN YET WILL SPARE ANY
DETAILS FOR THE MOMENT GIVEN THAT TIME RANGE.

&&

.PREV DISCUSSION... /ISSUED 1230 AM EST SUN DEC 21 2008/

AVIATION...
06Z TAFS.

TAFS OVERALL IN GOOD SHAPE WITH ARRIVAL OF STG COLD FRONT INTO
KSBN SOMETIME AROUND 7Z AND KFWA A FEW HOURS LATER. QUICK INCREASE
IN WINDS BEHIND THE FRONT WITH GUSTS IN THE 25 TO 35 KT RANGE
COMMON. EXPECTED BURST OF SOMEWHAT HEAVIER SNOW NOW MOVING KSBN
AND WILL CLIP KFWA AS WELL. AFTER THAT MAINLY BLOWING SNOW AND ON
AND OFF SNOW SHOWERS TO PREVAIL UNTIL MORNING WHEN THINGS
TRANSITION TO MORE LAKE EFFECT AND FOCUS TO NEAR OR NORTH OF KSBN.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...WIND CHILL ADVISORY UNTIL 1 PM EST /12 PM CST/ MONDAY FOR
     INZ003>009-012>018-020-022>027-032>034.

MI...WIND CHILL ADVISORY UNTIL 1 PM EST MONDAY FOR MIZ080-081.

     WINTER STORM WARNING UNTIL 10 AM EST MONDAY FOR MIZ077>079.

OH...WIND CHILL ADVISORY UNTIL 1 PM EST MONDAY FOR OHZ001-002-004-005-
     015-016-024-025.

LM...HEAVY FREEZING SPRAY WARNING UNTIL 5 AM EST MONDAY FOR LMZ043-
     046.

     GALE WARNING UNTIL 5 AM EST MONDAY FOR LMZ043-046.

&&

SHORT TERM...FISHER
LONG TERM...HOLSTEN
AVIATION...FISHER