Heavy Snow in Michigan, December 24 to 25, 2003

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
300 PM EST WED DEC 24 2003

.DISCUSSION...
INTERESTING WEATHER SCENARIO UNFOLDING ACROSS NORTHERN LOWER WHICH
EXTENDS INTO ONTARIO.  FAIRLY LARGE CLOSED UPPER LOW WAS, MORE OR
LESS, OVER THE STATE OF MICHIGAN WITH SEVERAL SHORT WAVES ROTATING
AROUND THIS LOW (EVEN DIFFICULT TO ASCERTAIN ON THE H2O VAPOR LOOP
THIS AFTERNOON).  HOWEVER, EXCELLENT MODEL CONSENSUS THIS 12Z RUN
WITH THE HANDLING OF THIS LOW AS WARM AIR ADVECTION ACROSS ONTARIO
(YES...WARM AIR ADVECTION) STREAMS INTO NORTHERN LOWER THEN TRACKS
SOUTH ACROSS THE REGION OVERNIGHT INTO THURSDAY MORNING...MORE ON
THIS IN A BIT.  H2O VAPOR DOES SHOW A HIGHLY AMPLIFIED PATTERN OVER
NOAM WITH PRONOUNCED RIDGE OVER THE PLAINS AND DEEP LOW OFF THE
PACIFIC NORTHWEST COAST TOWARD LOWER ALASKA.  AT THE SURFACE, LOW
PRESSURE WAS HEADING NORTH INTO NEW ENGLAND WITH INVERTED TROF AXIS
ACROSS NORTHERN LOWER ONCE AGAIN (LEAD TROF IS CURRENTLY INTO THE
OHIO VALLEY).

KAPX RADAR SHOWING LEADING EDGE OF SNOW ADVANCING SOUTH WHICH IS ON
THE LEADING EDGE OF MID LEVEL WARM AIR ADVECTION.  MODELS LATCH ONTO
THIS FEATURE QUITE WELL WHICH BRINGS SNOW INTO THE TRI-CITIES AND
THUMB THIS EVENING THEN SPREADS SOUTH OVERNIGHT TOWARD M59
CORRIDOR.  LAYER Q-VECTOR CONVERGENCE IS QUITE IMPRESSIVE (STRONGER
ON THE GFS) AND LAYER OMEGA VALUES RESPOND WITH GOOD VERTICAL MOTION
RIGHT AROUND THE -12C (GOOD DENDRITIC ICE GROWTH POTENTIAL).  700MB
SHORT WAVE AXIS IS FURTHER WEST ON THE GFS/ETA-XX THAN COMPARED THE
ETA WHICH LOOKS A BIT MORE CORRECT BASED ON UPSTREAM CONDITIONS.
285K ISENTROPIC SURFACES OFF THE GFS ARE EQUALLY IMPRESSIVE WITH
STRONG ASCENT ON THE SURFACE, VERY LOW CPD/S AND BULLET OF NET
ISENTROPIC ADIABATIC OMEGA CENTERED OVER THE NORTHERN 1/2 OF THE CWA
IN THE MORNING...SLIDING SOUTHEAST ACROSS LAKE ST CLAIR BY 18Z
(ETA-XX IS IN VERY CLOSE AGREEMENT...IF NOT A LITTLE STRONGER
SIGNAL). 850-700 SPECIFIC HUMIDITIES AROUND 2 G/KG BUT WE NOW ADD IN
SOME LAKE HURON MOISTURE...850MB TEMPS ARE WARMING WITH TIME BUT
INITIALLY COLD ENOUGH FOR CONTRIBUTION TO ADD ADDITIONAL QPF.  WITH
THE ABOVE SIGNALS, AND SNOW ALGORITHMS POINTING TOWARD 4...WE WILL
HOIST WINTER WEATHER ADVISORIES FOR SNOW FOR LOCATIONS ALONG AND
NORTH OF M59 OVERNIGHT INTO THURSDAY MORNING.  GIVEN FORECAST LOW
LEVEL WIND FIELD...CURRENT THOUGHTS ARE SOME DOWNSLOPE COMPONENT
WILL CUT OFF AMOUNTS SOUTH OF M59 BUT OVERNIGHT CREW WILL NEED TO
RE-EVALUATE WITH NEW GUIDANCE.  OTHERWISE...HIGHER AMOUNTS WILL
LIKELY BE DOWNWIND OF LAKE HURON WHERE 3-5 OF SNOW COULD
FALL...2-4 AWAY FROM THE LAKE.

SYSTEM SLOWLY LIFTS NORTHEAST THURSDAY NIGHT WITH RISING HEIGHTS
OVER THE STATE.  SOME RESIDUAL ACTIVITY MAY HANG ON ALONG THE
LAKESHORE EARLY BUT NO ADDITIONAL ACCUMULATIONS EXPECTED.  LOW
CLOUDS WILL HANG ON EAST AS LOW-LEVEL WAA WILL ENHANCE THE INVERSION
AND WITH FRESH SNOW COVER, BUT WITH RIDGE SETTLING IN ACROSS LAKE
MICHIGAN WE MIGHT ENOUGH BREAKS DEVELOPING OVERNIGHT INLAND FOR A
PTCLOUDY SKY.  TEMPERATURES WILL BE TRICKY BUT WE WILL HOLD ONTO THE
LOWER HALF OF THE 20S.

RIDGE AT ALL LEVELS MOVES OVERHEAD FRIDAY FOR A NICE END TO THE
WEEK.  WITH HIGHER THICKNESS, TEMPERATURES WOULD EASILY CLIMB INTO
THE 40S BUT WITH EXPECTED SNOW COVER...WE WILL HOLD TEMPS BACK INTO
THE UPPER 30S (CLOSER TO THE MAV NUMBERS).

INTO THE WEEKEND, VERY IMPRESSIVE WAA DEVELOPS OVER THE CENTER OF
THE NATION AS DEEP TROF AND STRONG JET OF >130KTS COMES ASHORE INTO
THE INTER-MOUNTAIN WEST.  MOISTURE TRANSPORT VECTORS AND THETA-E
ADVECTION ORIGINATE FROM THE GULF OF MEXICO WHICH QUICKLY HEAD
NORTH INTO THE CENTER OF THE NATION.  WITH WARM AIR WELL HEADING
NORTH, PRECIP IN OUR CWA WILL BE IN THE FORM OF RAIN, WHICH SHOULD
HOLD OFF UNTIL AFTER MIDNIGHT SATURDAY.  NOSE OF LOW LEVEL JET
(>45KTS) HEADS RIGHT INTO THE STATE ON SUNDAY WHERE WE STAND THE
BEST CHANCE FOR RAIN.  THEREAFTER, MODELS SLOWLY COMING AROUND
TOWARD A BRIEF SHOT OF WINTRY WEATHER FOR EARLY NEXT WEEK BUT STILL
SOME DISAGREEMENT AS ECMWF/GFS/ETA-XX ALL FAVOR EACH OTHER IN
DPROG/DT ANALYSIS.  FOR NOW WE WILL TREND TOWARD RAIN/SNOW MIX FOR
TUESDAY WITH A CHANCE FOR LINGERING SNOW SHOWERS FOR MID NEXT
WEEK...COULD BECOME INTERESTING TOWARD NEW YEARS DAY.

COLLABORATED WITH APX AND GRR...THANKS

&&

.DTX WATCHES/WARNINGS/ADVISORIES...WINTER WEATHER ADVISORY FOR SNOW
ALONG AND NORTH OF M59 FROM 05Z-17Z THURSDAY.

&&

BGM

EXPERIMENTAL GRAPHICAL FORECASTS ARE AVAILABLE ONLINE AT
HTTP://WWW.CRH.NOAA.GOV/DTX  (ALL LOWER CASE)

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
345 PM EST WED DEC 24 2003

MIZ047>049-053>055-251200-
BAY-HURON-MIDLAND-SAGINAW-SANILAC-TUSCOLA-
345 PM EST WED DEC 24 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST LOWER MICHIGAN

.DAY ONE...TODAY AND TONIGHT

A WINTER WEATHER ADVISORY IS IN EFFECT FROM MIDNIGHT TONIGHT TO NOON
THURSDAY.

AN UPPER LEVEL DISTURBANCE WILL BRING SNOW TO THE AREA TONIGHT WITH
AROUND ONE INCH OF NEW ACCUMULATION EXPECTED BY DAYBREAK.

PLEASE REFER TO THE LATEST WINTER WEATHER ADVISORY FOR ADDITIONAL
INFORMATION.

.DAY TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

A WINTER WEATHER ADVISORY IS IN EFFECT FROM MIDNIGHT TONIGHT TO NOON
THURSDAY.

SNOW WILL CONTINUE THURSDAY MORNING...WITH PERIODS OF HEAVY SNOW
POSSIBLE GENERALLY BEFORE 10 AM. TOTAL ACCUMULATIONS OF 3 TO 5
INCHES ARE EXPECTED.

PLEASE REFER TO THE LATEST WINTER WEATHER ADVISORY FOR ADDITIONAL
INFORMATION.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IN NOT ANTICIPATED. HOWEVER...SNOWFALL REPORTS
WOULD BE APPRECIATED.

MIZ060>063-068>070-251200-
GENESEE-LAPEER-LIVINGSTON-MACOMB-OAKLAND-SHIAWASSEE-ST. CLAIR-
345 PM EST WED DEC 24 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST LOWER MICHIGAN

.DAY ONE...TODAY AND TONIGHT

A WINTER WEATHER ADVISORY IS IN EFFECT FROM MIDNIGHT TONIGHT TO NOON
THURSDAY.

AN UPPER LEVEL DISTURBANCE WILL BRING SNOW TO THE AREA LATE TONIGHT
WITH ACCUMULATIONS OF LESS THAN AN INCH EXPECTED.

PLEASE REFER TO THE LATEST WINTER WEATHER ADVISORY FOR ADDITIONAL
INFORMATION.

.DAY TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

A WINTER WEATHER ADVISORY IS IN EFFECT FROM MIDNIGHT TONIGHT TO NOON
THURSDAY.

SNOW WILL CONTINUE THURSDAY MORNING...WITH PERIODS OF HEAVY SNOW
POSSIBLE GENERALLY BEFORE 10 AM. TOTAL ACCUMULATIONS OF 2 TO 4
INCHES ARE EXPECTED.

PLEASE REFER TO THE LATEST WINTER WEATHER ADVISORY FOR ADDITIONAL
INFORMATION.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IN NOT ANTICIPATED. HOWEVER...SNOWFALL REPORTS
WOULD BE APPRECIATED.

MIZ075-076-082-083-251200-
LENAWEE-MONROE-WASHTENAW-WAYNE-
345 PM EST WED DEC 24 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR FAR SOUTHEAST LOWER MICHIGAN

.DAY ONE...TODAY AND TONIGHT

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAY TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

SNOW IS EXPECTED TO FALL...PRIMARILY DURING THE MORNING HOURS...AS
AN UPPER LEVEL DISTURBANCE SWINGS BY THE REGION. ACCUMULATIONS OF
1 TO 2 INCHES WILL BE POSSIBLE...WITH HEAVIER AMOUNTS EXPECTED FROM
THE M 59 CORRIDOR NORTH.

GIVEN SOME DEGREE OF UNCERTAINTY IN THE TRACK OF THIS DISTURBANCE...
THERE IS SOME CHANCE THAT ACCUMULATIONS MAY BE SLIGHTLY HIGHER FROM
THE CITY OF DETROIT SOUTH TO MONROE.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IN NOT ANTICIPATED. HOWEVER...SNOWFALL REPORTS
WOULD BE APPRECIATED.

GURNEY