Winter Storm in Michigan, January 22, 2005

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1130 PM EST FRI JAN 21 2005

.UPDATE...

PHASING OFF THE LEAD SHORTWAVE AND STRONG ARCTIC VORTICITY NOW
DIVING INTO MINNESOTA SEEMS TO BE TAKING PLACE A BIT QUICKER THAN
MODELS SUGGEST. LEAD SYSTEM HAS BY AND LARGE DEVIATED FROM ITS
EAST-SOUTHEAST TRACK AND SEEMS TO BE HEADING DUE EAST IN RESPONSE
TO SECOND STRONGER SHORTWAVE DROPPING IN BEHIND IT (PER SATELLITE
INTERPRETATION).

THIS SHOULD BRING HEAVIER BAND OF SNOW FARTHER NORTH INTO THE CWA...
AND ALSO LEAD TO A QUICKER DEEPENING OF LOW PRESSURE ON SATURDAY AS
THE TWO SYSTEMS FINISH THEIR PHASING. 88D MOSAIC SHOWS A WIDE AREA OF
SNOW...WITH THE LEAD SHORTWAVE FORCING A VERY HEAVY AREA OF
SNOW ON THE LEADING EDGE OF THIS OVERALL EXPANSE. ROCKFORD IL HAS
PICKED UP 6 INCHES IN ABOUT 4 HRS...AS OF 11 PM. THIS AREA...MUCH
LIKE THE SATELLITE REPRESENTATION...SEEMS TO BE EXPANDING DUE EAST
IF NOT JUST A TOUCH NORTH OF DUE EAST.

HAVE ADJUSTED THE ADVISORY/WARNING BREAKUP ACCORDINGLY...EXPANDING
THE WARNING ANOTHER ROW OF COUNTIES NORTH TO INCLUDE LIVINGSTON...
OAKLAND AND MACOMB. IN ADDITION...HAVE UPGRADED THE WATCH FOR HURON
SANILAC AND ST CLAIR COUNTIES TO A WARNING FOR SATURDAY INTO THE
EVENING. IN THE THUMB...ACTUAL WIDESPREAD SNOW AMOUNTS MIGHT HAVE
TROUBLE GETTING TO WARNING CRITERIA...BUT LAKE ENHANCEMENT/EFFECT
WILL HELP PUSH LOCAL AREAS OVER THE TOP. NOT THAT ANYONE WILL BE
ABLE TO MEASURE IT AS THE MAIN CONCERN IS FOR 30 TO 40 MPH NORTHEAST
WINDS TO BLOW THE NEW SNOW AND EXISTING 6 (TO LOCALLY 12+) INCHES OF
POWDERY SNOW ON THE GROUND ALREADY. THIS WILL BE ESPECIALLY TRUE THE
NEARER ONE IS TO LAKE HURON. THESE WINDS...AND LAKE EFFECT...WILL
HOLD ON WELL INTO THE EVENING HOURS...HENCE THE LONGER DURATION IN
THESE THREE COUNTIES. COULD BE QUITE NASTY UP THERE LATE SATURDAY.

&&

.AVIATION...

BIG TROUBLE WILL BE TIMING IN LOW VSBYS/CEILINGS AS AREA OF SNOW
FROM APPROACHING CLIPPER. PLENTY OF VSBYS AT 1/4-1/2 MILE AROUND
CHICAGO BACK  INTO PARTS OF WI ATTM...AND WOULD EXPECT THESE
CONDITIONS TO SPREAD INTO THE DTW/DET AREAS TOWARD MORNING.
CONDITIONS WILL BE SLIGHTLY BETTER HEADING NORTH TO FNT AND MBS...OR
AT LEAST THE WORST CONDITIONS WILL BE OF A SHORT DURATION...AS MAIN
FORCING WITH THE COMING STORMS SLIDES SOUTH OF THE CWA. WILL TREND
IN SLIGHTLY MORE OPTIMISTIC CONDITIONS DURING THE MORNING TOMORROW.
MAIN SNOW THEN MOVES EAST OF AREA IN THE 18Z TO 21Z TIMEFRAME...WITH
IMPROVING VSBYS (AND EVENTUALLY CEILINGS). WINDS WILL BE RATHER GUSTY
THROUGH THE DAY SATURDAY...BUT WILL START TO EDGE OFF BY LATE IN THE
FORECAST.

&&

.SHORT TERM...TONIGHT AND SATURDAY...ISSUED AT 435 PM EST.

CLOUD SHIELD IN ADVANCE OF THE NEXT CLIPPER SYSTEM STARTING TO MAKE
INROADS ACROSS LAKE MICHIGAN. HOWEVER, THE LEADING EDGE HAS BEEN
ERODING AS IT MOVES INTO THE DRIER COLUMN OVER LOWER MICHIGAN.  LAKE
EFFECT SNOW SHOWERS OFF OF LAKE HURON HAVE WANED AS THE INVERSION
HEIGHTS HAVE LOWERED SUBSTANTIALLY AND THE FLOW HAS VEERED TO
SOUTHEASTERLY.  DEWPOINTS UPSTREAM OF THE FORECAST AREA ACROSS
SOUTHWEST ONTARIO ARE RUNNING IN THE TEENS BELOW ZERO.  EXPECT THIS
DRY AIR TO HAVE AN IMPACT ON THE ONSET OF SNOWFALL ASSOCIATED WITH
THE CLIPPER TONIGHT.

NCEP SUITE IS CONVERGING ON A SOLUTION WITH RESPECT TO THE SHORTWAVE
RESPONSIBLE FOR NEXT SYSTEM. THE TREND HAS BEEN BACK TOWARD THE
SOUTH WITH THE PAST FEW CYCLES, BRUSHING THE FORECAST AREA WITH THE
SWATH OF HEAVIER PRECIPITATION.  THE AIRMASS ACROSS THE FORECAST
AREA WILL REMAIN COLD AND MODEL PROJECTIONS INDICATE THAT THERE WILL
BE APPRECIABLE LIFT WITHIN THE MAX DENDRITIC GROWTH REGION (-13 TO
-18C). HOWEVER, THE SNOW WILL BE QUITE POWDERY AS THERE WILL BE
LITTLE AGGREGATION OF FLAKES AS THE COLUMN WILL REMAIN COLDER THAN
-8C.  THE PRIMARY LIFTING MECHANISM WILL BE ISENTROPIC LIFT ABOVE
700MB WITH SOME MID-LEVEL FRONTOGENESIS AROUND 600-500MB. THE
STABILITY ABOVE THIS LAYER WILL BE QUITE LOW AS THE UPPER WAVE
SWINGS ACROSS, STEEPENING THE LAPSE RATES. HOWEVER, THE BEST
LOW-LEVEL FORCING WILL TRAVERSE SOUTH OF THE FORECAST AREA, WHERE
THE BETTER MOISTURE WILL RESIDE. THE MID-LEVEL FGEN WILL TRANSITION
TO MID-LEVEL DEFORMATION DURING THE MORNING, GIVING A PROLONGED
PERIOD OF SNOWFALL ACROSS THE SOUTHERN HALF. MODEL PRECIP FORECASTS
APPEAR TO BE SLIGHTLY ON THE HIGH SIDE GIVEN THE DRY AIR IN PLACE,
WHICH WILL EAT AWAY AT THE INITIAL SURGE, AND THE BEST DEEP MOISTURE
SHOULD REMAIN TIED TO THE LOW-MID LEVEL FRONTOGENESIS ACROSS INDIANA
AND OHIO.  FURTHERMORE, PROJECTED MIXING RATIOS ONLY CLIMB TO AROUND
2G/KG NEAR THE BORDER WHICH DOES NOT SEEM TO SUPPORT THE NEARLY HALF
INCH IF QPF IN THE SOUTH.  HAVE OPTED TO GO WITH A WARNING ACROSS
THE SOUTHERN FOUR COUNTIES FOR 5 TO 10 INCHES, WITH AN ADVISORY TO
THE NORTH.

THE GRADIENT WILL INCREASE SUBSTANTIALLY EARLY SATURDAY PRODUCING
STRONG NORTHEAST WINDS ACROSS THE ENTIRE AREA LEADING TO
CONSIDERABLE BLOWING AND DRIFTING OF SNOW EVERYWHERE.

AS THE SYSTEM PULLS TO THE EAST OF THE REGION LAKE HURON WILL BECOME
PRIMED FOR LAKE EFFECT SATURDAY AFTERNOON.  INVERSION BASES SHOULD
CLIMB TO AROUND 8KFT ALLOWING FOR LAKE INDUCED CAPES TO CLIMB TO
NEAR 350J/KG.  EXPECT MULTIPLE WIND PARALLEL BANDS TO SETUP ACROSS
THE THUMB COUNTIES.  THE FLOW SHOULD REMAIN STRONG ENOUGH TO KEEP
THE BANDS SOMEWHAT TRANSIENT BUT THE POTENTIAL FOR SUBSTANTIAL
ACCUMULATION STILL EXISTS.  HAVE OPTED TO KEEP THE WATCH GOING FOR
THE LAKE HURON COUNTIES AS THE SNOW WILL START THERE LATE TONIGHT,
GIVING A LITTLE MORE TIME TO ASSESS THE IMPACT OF LAKE HURON LATER
TOMORROW.

&&

.LONG TERM...BEGINNING SATURDAY NIGHT...ISSUED AT 435 PM EST.

AT 500 MB...MODELS CONTINUE IN GOOD AGREEMENT WITH SHARP TROUGH
CONTINUING TO PIVOT SOUTHEAST SATURDAY NIGHT...SOME SHEARED
VORTICITY IN NORTHWEST FLOW SUNDAY NIGHT AND MONDAY...WITH STILL
DECENT MODEL CONSENSUS DEPICTING PROGRESSIVE PACIFIC SHORTWAVE
TROUGH PASSING ACROSS GREAT LAKES REGION AT MID WEEK...ANOTHER
SHORTWAVE TROUGH APPROACHING GREAT LAKES BY NEXT FRIDAY NIGHT. AT
THE SURFACE...THE LOW EARLIER PASSING SOUTH OF THE GREAT LAKES WILL
MOVE OFF THE ATLANTIC COAST SATURDAY NIGHT...RIDGE MOVES IN BY
SUNDAY...THEN SAGS SOUTH AHEAD OF WEAK TROUGH MONDAY. EXTENDED
MODELS STILL SHOWING MID WEEK SURFACE LOW TRAVERSING THE NORTHERN
LAKES REGION...THEN COLDER WITH RIDGE BUILDING IN THURSDAY.

MOISTURE DEPTH SHARPLY DECREASES EARLY SATURDAY NIGHT...AS
SUBSIDENCE SETS IN. THIS SUBSIDENCE SATURDAY NIGHT SHOULD ALLOW
INVERSION HEIGHTS NEAR LAKE HURON TO LOWER STEADILY...THUS LIMITING
FURTHER LAKE EFFECT POTENTIAL DESPITE MEAN LOW LEVEL NORTHERLY WINDS
AND DELTA T AT LEAST MINUS 20. HOWEVER...ETA STILL DEPICTS GOOD 950
MB CONVERGENCE LURKING ACROSS EASTERN COUNTIES OF SOUTHEAST MI
THROUGH EARLY SATURDAY NIGHT...AS WELL AS GOOD LOW LEVEL OMEGA LIFT.
SO...WILL PLAN ON UP TO ABOUT 2 MORE INCHES EARLY SATURDAY NIGHT.

LOW TO MID LEVEL OMEGA FIELDS...THEN...INDICATIVE OF GOOD SUBSIDENCE
ENTIRE FORECAST AREA BY SUNDAY MORNING...THEN FAIRLY GOOD LIFT
SETTING UP SUNDAY NIGHT AND MONDAY AHEAD OF NEXT TROUGH. 850 TO 500
MB QVECTOR DIVERGENCE/SUBSIDENCE SETTLING IN SATURDAY NIGHT...GOOD
CONVERGENCE SUNDAY NIGHT INTO MONDAY TO HELP SQUEEZE OUT MORE
SNOW...BUT AMOUNTS SHOULD GENERALLY BE LIGHT. 850 TO 700 MB
FRONTOGENESIS ALSO MODEST SUNDAY NIGHT AND MONDAY...ALONG WITH
MODEST DEVELOPING LOW LEVEL CONVERGENCE AND 285K ISENTROPIC LIFT
WITH PLUNGING CONDENSATION PRESSURE DEFICITS.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
.MI...
WINTER STORM WARNING...OVERNIGHT AND SATURDAY...
    LIVINGSTON...OAKLAND...MACOMB...WAYNE...WASHTENAW...LENAWEE AND
    MONROE COUNTIES.

WINTER STORM WARNING...SATURDAY INTO SATURDAY NIGHT...
    HURON...SANILAC...AND ST CLAIR COUNTIES.

SNOW AND BLOWING SNOW ADVISORY...OVERNIGHT AND SATURDAY...
    MIDLAND...BAY...SAGINAW...TUSCOLA...SHIAWASSEE...GENESEE...
    LAPEER COUNTIES.

.LAKE HURON...GALE WARNING ALL AREAS...SATURDAY.
.LAKE ST CLAIR...SMALL CRAFT ADVISORY...SATURDAY.
.MI WATERS OF LAKE ERIE...SMALL CRAFT ADVISORY...SATURDAY.

&&

DEG/MANN/DWD

HAZARDOUS WEATHER OUTLOOK FOR SOUTHEAST MICHIGAN
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
455 PM EST FRI JAN 21 2005

MIZ075-076-082-083-221200-
LENAWEE-MONROE-WASHTENAW-WAYNE-
455 PM EST FRI JAN 21 2005

THIS HAZARDOUS WEATHER OUTLOOK IS FOR FAR SOUTHEAST MICHIGAN.

.DAY ONE...TONIGHT

A WINTER STORM WARNING IS IN EFFECT...BEGINNING AT 2 AM. PLEASE
REFER TO THE LATEST URGENT WINTER WEATHER STATEMENT FOR DETAILS.

.DAY TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

THE WINTER STORM WARNING REMAINS IN EFFECT UNTIL 6 PM SATURDAY.
PLEASE REFER TO THE LATEST URGENT WINTER WEATHER STATEMENT FOR
DETAILS.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT PLANNED...HOWEVER SNOWFALL REPORTS WOULD
BE APPRECIATED TONIGHT AND SATURDAY.

MIZ047-048-053-054-060>062-068>070-221200-
BAY-GENESEE-LAPEER-LIVINGSTON-MACOMB-MIDLAND-OAKLAND-SAGINAW-
SHIAWASSEE-TUSCOLA-
455 PM EST FRI JAN 21 2005

THIS HAZARDOUS WEATHER OUTLOOK IS FOR AREAS GENERALLY ALONG AND
NORTH OF INTERSTATE 96 AND 696.

.DAY ONE...TONIGHT

A SNOW AND BLOWING SNOW ADVISORY IS IN EFFECT...BEGINNING AT 2 AM.
PLEASE REFER TO THE LATEST URGENT WINTER WEATHER STATEMENT FOR
DETAILS.

.DAY TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

THE SNOW AND BLOWING SNOW ADVISORY REMAINS IN EFFECT UNTIL 6 PM
SATURDAY. PLEASE REFER TO THE LATEST URGENT WINTER WEATHER STATEMENT
FOR DETAILS.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT PLANNED...HOWEVER SNOWFALL REPORTS WOULD
BE APPRECIATED TONIGHT AND SATURDAY.

MIZ049-055-063-221200-
HURON-SANILAC-ST. CLAIR-
455 PM EST FRI JAN 21 2005

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PARTS OF THE THUMB REGION

.DAY ONE...TONIGHT

A WINTER STORM WATCH IS IN EFFECT...BEGINNING AT 4 AM TONIGHT.
PLEASE REFER TO THE LATEST URGENT WINTER WEATHER STATEMENT FOR
DETAILS.

.DAY TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

THE WINTER STORM WATCH REMAINS IN EFFECT ON SATURDAY. PLEASE REFER
TO THE LATEST URGENT WINTER WEATHER STATEMENT FOR DETAILS.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT PLANNED...HOWEVER SNOWFALL REPORTS WOULD
BE APPRECIATED LATE TONIGHT THROUGH SATURDAY.

LCZ422-423-460-LEZ444-LHZ421-422-441>443-462>464-221200-
SAGINAW-BAY-SOUTHERN LAKE HURON-LAKE HURON NEARSHORE FROM PORT
AUSTIN TO PORT HURON-ST CLAIR RIVER-LAKE ST CLAIR-DETROIT
RIVER-MICHIGAN WATERS OF LAKE ERIE-
455 PM EST FRI JAN 21 2005

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SAGINAW BAY...SOUTHERN LAKE
HURON...THE ST CLAIR RIVER...LAKE ST CLAIR...THE DETROIT RIVER...AND
THE MICHIGAN WATERS OF LAKE ERIE.

.DAY ONE...TONIGHT

HAZARDOUS WEATHER IS NOT EXPECTED AT THIS TIME.

.DAY TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

A SMALL CRAFT ADVISORY IS IN EFFECT SATURDAY INTO SATURDAY NIGHT
FOR ALL NEARSHORE WATERS OF LAKE HURON...LAKE ST CLAIR AND LAKE
MICHIGAN. PLEASE REFER TO THE LATEST MARINE FORECASTS FOR DETAILS.

SMALL CRAFT ADVISORY CONDITIONS WILL BE POSSIBLE AGAIN BY SUNDAY
AND ALSO ON WEDNESDAY OF NEXT WEEK.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT PLANNED.

GURNEY