Winter Storm in Michigan, March 15, 2002

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
1050 PM EST THU MAR 14 2002

00Z RAOBS/WV LOOP AND RUC ANAL SHOW VIGOROUS SHRTWV E OF UPR TROF
OVR THE WRN CONUS MOVG NE TOWARD THE GRT LKS ON UPWND SIDE OF UPR
RDG IN THE SE CONUS. ASSOCIATED SFC LO OVR SE IA ATTM WITH ATTENDANT
WARM FNT TO THE E...S OF HI PRES RDG UNDER UPR CONFLUENCE BTWN SRN
BRANCH IMPACTING CONUS AND ARCTIC BRANCH ACRS SCNTRL CAN. BAND OF
HVY SN HAS SET UP IN CCB FM MPX TO IWD/IRON RVR TO MQT TO JUST N OF
ERY WITH MAX REFLECTIVITY ABV 45DBZ. RPRTS FM SPOTTERS INDICATE SN
FALLING AT AN INCH AN HOUR OR BETTER...WITH RPRT FM IRON RVR AREA
SHOWING 5 INCHES ALREADY BY 01Z AND 8 INCHES AT BOVINE (S OF LANSE)
BY 02Z. PW ONLY ABOUT 0.5 INCHES...AND 3G/KG AVBL AT H7. AXIS OF
HEAVIEST SN IS ON COLD SIDE OF PAST/PROJECTED H7 LO TRACK PER
RAOBS/EARLIER MODEL FCSTS. LIFT/SN RATES ENHANCED ABV IMXR/PW BY
SHARP H85-7 FRONTOGEN IN APRNT COUPLED JETS OVR NRN ONTARIO AND THE
ONE LIFTING NE INTO MN SUPPORTING STRG SHRTWV. SOME EMBEDDED
CNVCTN...A FEW LTG STRIKES APRNT FM MPX TO NW WI WHERE CLD TOP TEMPS
DCRSG IN LEFT EXIT OF JET MAX SUPPORTING SHRTWV. THE BAND OF HVY SN
LIFTING SLOWLY N THRU CWA...BUT MORE SLOWLY OVR THE W. PCPN
INTENSITY FARTHER S QUITE A BIT LGTER IN UPR DRYING DEPICTED ON
WV/IR IMAGERY. ESC/MNM/ISQ RPTG VFR VSBYS...BUT LATEST RPRT FM MNM
INDICATES AN INCH OF -PL. FZRA FALLING OVR CNTRL WI ON WARM SIDE OF
H7 LO TRACK EVEN THOUGH 00Z GRB SDNG SHOWS NO ABV FRZG LYR. DRY AIR
EVIDENT ON THIS SDNG ABV H6.

MAIN FCST CONCERNS THIS PACKAGE ARE SN AMTS OVRNGT. MODELS SEEM TO
BE HAVING A HARD TIME DEFINING THE EXACT POSITION OF THE VERY SHARP
UVV THAT MUST BE ACCOMPANYING THE AXIS OF HVY SN... WITH EARLIER
RUNS DEPICTING THE AXIS TOO FAR S. FCST TRACK OF H7 LO SEEMS TO BE A
BETTER INDICATOR OF DELINEATION BTWN HVY SN ON COLD SIDE AND LGTER
PCPN ON THE WARM SIDE. 00Z ETA SHOWS H7 LO TRACK FM NR MPX TO AUW
AND GRM. THIS TRACK FAIRLY CONSISTENT WITH EARLIER RUN AND SUGS
GOING HEADLINES WITH WRNGS OVR ALL BUT MNM-ESC-ISQ-ERY (ZNS ON WARM
SIDE OF H7 LO TRACK WHERE UPR DRYING MOST ACCENTUATED) ON TRACK.
HAVE ALREADY UPDATED MAX SN FCST OVR THE W TO 18 INCHES BASED ON
SPOTTER RPRTS AND ASSUMPTIONS ON FRONTOGEN/COUPLED JET ENHANCEMENTS.
GIVEN EXPANDING COLD CLD TOPS/LTG STRIKES UPSTREAM CLOSER TO ACTUAL
H7 LO CENTER...WL UP MAX AMTS TO 20 INCHES OVR IWD/ONT WHERE CNVCTN
IS MOST LIKELY TO PASS BEFORE ETA SHOWS UPR DVGC IN COUPLED JETS
DIMINISHING LATER TNGT AND WHERE HIER RADAR REFLECTIVITIES APPEAR TO
BE PERSISTING MORE. WL TEND TO LWR MAX SN AMTS AND MAINTAIN OVR THE
SE ON SRN SIDE OF H7 LO TRACK WHERE NEW ETA SHOWS UPR DRYING AOB H7
BY 12Z. INCRSG UPSLOPE AND CYC NELY FLOW INTO THE NCTNRL ZNS TO THE
NW OF SFC LO TRACK INTO NRN LK MI WL ALSO ENHANCE ACCUMS THERE EVEN
THOUGH BEST DYNAMICS WL MISS JUST TO THE NW. ETA SHOWS CCB STRUCTURE
WEAKENING AND DEPARTING CWA BY 18Z FRI AS DYNAMICS COLLAPSE. SINCE
THIS TREND IS EARLIER THAN INDICATED BY EARLIER RUNS...HAVE HASTENED
DIMINISHING OF SN AND LWRD FCST ACCUMS FOR FRI.

AFDMQT FM DAYSHIFT FOR LATER PDS:

THE SHRTWV TROF WILL SLIDE TO THE E OF CWA ON FRI. SFC LOW WILL MOV
TO KAPN BY 18Z AND INTO E ONT BY 00Z SAT. QPF DROPPING TO .10-.20 IN
THE AFTN...AND TO FLURRIES IN THE EVE. MDLS SHOW NO LOW LVL
CONVERGENCE WITH THE CAA. THIS WOULD LIMIT AND LES. HOWEVER...WOULD
NOT RULE OUT SOME WEAK ENHANCEMENT WITH THE N WNDS.

MDLS INDCT A RDG TO CONT TO BUILD OVR N PLAINS ON SATURDAY. THE
NW CST LOW WILL START TO DIG INTO THE GRT BASIN. WEAK SHRTWVS CONT
TO BE EJECTED OUT AHD OF THE THIS LOW. ONE WILL SWEEP ACRS N WI ON
SAT.

SFC RDG WILL BE TREKKING SLOWLY ACRS THE UPR GRTLKS...WHILE ANOTHER
LOW AND ASSOC CDFNT WILL BE DVLG OVR CNTRL HI PLAINS. SAT AND SAT
NGT LOOKS DRY. BY SUN THE W CST LOW WILL HAVE DUG INTO THE GRT
BASIN. THE RDG WILL MOV INTO ONT/QUE AND LWR GRTLKS ON SUN. SFC RDG
WILL MOV INTO W QUE. A SHRTWV WILL MOV INTO N PLAINS. CAN GEM SUG
THAT THE SHRTWV WILL DEEPEN INTO A CLOSED LOW AS IT MOV ACRS U.P. ON
MON. AVN/ECMWF KEEPING THE SYS A LTL WEAKER. IN ANY CASE...SNOW IS
LIKELY AS 1000-500MB THICKNESSES WILL REMAIN BELOW 540M.
CAN/ECMWF/MRF ALL SHOW INVERTED TROF OVR N MN BY 12Z MON. THERE IS
CONSIDERABLE DISAGREEMENT ON STRENGTH HOWEVER. MDLS SHOWING THE SNOW
WILL END ON TUE. A DEEP TROF WILL DIG INTO THE S RCKY ON
WED...EJECTING MORE SHRTWV OUT AHD OF IT THRU THE U.P. A SHRTWV WILL
SHOT THRU THE CWA ON WED. A SFC LOW WILL REACH E ONT. CYC FLOW
BEHIND THIS LOW WILL CAUSE INCR CAA AND LK DELTA-TS OF 14C. LES
POSSIBLE. RDG WILL MOV OVR CWA ON ON THU...REDUCING WNDS...DRAWING
IN DRIER AIR AND ENDING LES.

COORDINATED WITH GRB...APX.

.MQT...WINTER STORM WRNG OVRNIGHT/FRI MRNG MIZ001>006-009>011.
       SNOW ADVY OVRNIGHT/FRI MRNG MIZ007-011-014.
       WINTER WEATHER ADVISORY OVRNIGHT/FRI MRNG MIZ012-013.

KC