Heavy Snow in Michigan, March 21, 2002

AREA FORECAST DISCUSSION...UPDATE FOR CHG OF GOGEBIC WRNG COND
NATIONAL WEATHER SERVICE MARQUETTE MI
340 AM EST THU MAR 21 2002

MAIN CONCERN WITH THIS FCST PACKAGE IS THE SN AND WNDS FOR TDA...AND
TNGT.

WV IMAGERY SHOWING A CLOSED LOW OVR HUDSON BAY EMBEDDED IN A
LONGWAVE TROF STRETCHING S FM THE N POLE. A RDG IS TRYING TO BUILD
OVR THE PAC NW SEPERATING THE HUDSON BAY TROF FM ANOTHER CLOSED LOW
EMBEDDED IN A LONGWAVE TROF OVR 140W. A SHRTWV IS PINWHEELING ARND
THE HUDSON BAY LOW THRU LK SUPERIOR ATTM...WHILE ANOTHER SHRTWV IS
OVR THE CAN PRAIRIES IS GETTING READY TO DO THE SAME. SFC ANLYS
INDCT A 1015MB SFC LOW OVR LWR MI WITH A CDFNT XTND SW INTO THE
CNTRL PLAINS. A BROAD RDG IS SLIDING DN THE LEE OF THE RCKY INTO THE
CNTRL PLAINS. ACYC FLOW ARND THIS RDG IS PROVIDING PLENTY OF CAA TO
THE FCST AREA THIS MRNG. THE RESULTS OF THIS RDG TRYING TO PUSH THE
LWR MI LOW AND CDFNT OUT OF THE UPR GRTLKS HAS DVLPD SOME TIGHT PRES
GRAD ACRS FCST AREAS GENERATING STRONG N WNDS. KMQT-88D SHOWING LES
BANDS SETTING UP OVR U.P.

MDLS IN GOOD AGREEMENT IN TIMING AND STRENGTH OF SYS MOV THRU FCST
AREA THRU FCST PERIOD. SEE NO REASON TO DISAGREE WITH THEM ATTM.

THE FIRST SHRTWV WILL SWING THRU FCST AREA BY 18Z TDA. A WEAK RDG
WILL SLIDE OVR CWA THIS MRNG FOLLOWING THE SHRTWV. THIS LIKELY ASSOC
WITH STRONG BAROCLINIC ZONE AND CAA ACRS CWA THIS MRNG. THIS WILL
HAMPER SNOWFALL ARND SR. WITH THE DEPARTURE OF THIS SHRTWV...Q-VEC
CONVERGENCE WILL FALL OFF ALSO. LOW LVL MSTR WILL CONT TO DIMINISH
TO <80 PCT BY 12Z...OVR ALL BUT E LK SUPERIOR AND CWA. CAA WILL DVLP
LK-850MB DELTA-TS OF 25C. THE WNDS WILL CONT TO BE STRONG THIS
MRNG...ON THE ORDER TO 15 TO 25 MPH WITH GUSTS TO 35 MPH. THUS GALES
XPC OVR THE LK TDA. THIS WILL HAVE A TENDENCY TO REDUCE THE FETCH
OVR THE WATER. LGTR WNDS AND MORE OUT OF THE NW IS XPC OVR E LK
SUPERIOR...THUS WITH REMANENTS OF THE SHRTWV STILL OVR E LK SUPERIOR
THIS MRNG...ALONG WITH WEAK LOW LVL CONVERGENCE...AND LONGER
FETCH...XPC TO SEE BEST ACCUM OVR THE E U.P. CONT TDA. LES FLOW
CHART FAVOR 4-6 IN/6HRS OVR THE E CWA...AND 1 TO 3 IN/6HRS OVR W.
ANOTHER WEAKER SHRTWV WILL PASS OVR W LK SUPERIOR BY 00Z INTO CNTRL
U.P. INCR Q-VEC CONVERGENCE OVR E LK SUPERIOR. 280K ISENTROPIC ANLYS
ALSO DEPICTING WEAK ASCENT OVR E LK SUPERIOR AS WELL. DELTA-TS WILL
BE AROUND 24C. BLYR WNDS CONVERGENCE ALSO INDCT CONVERGENCE OVR E LK
SUPERIOR. MEAN SFC-850MB RH OVR E LK WILL ALSO BE >80 PCT. COND MUCH
WEAKER OVR THE W LK SUPERIOR. HOWEVER...THE KEWEENAW PENSULA WILL
STILL HAVE THE LONG FETCH WITH A W WND...AND FAVORABLE FOR MORE
ACCUM LATE THIS AFTN AND TNGT. LES CHART STILL SUPPORTS 4-6/6HRS
OVR E LK SUPERIOR LATE THIS AFTN. OVR THE W COND WEAKER WITH SUG 1
TO 3 INCHES. WILL KEEP THE LES ADVISORY UP FOR THE GOGEBIC AND
ONTONAGON SINCE ACCUM WILL CONT INTO EARLY MRNG HRS. POSSIBLY DROP
AFT SR. WILL KEEP LES WARNING FOR ALGER AND XTND IT INTO
TNGT...WHILE ADDING LUCE. HEAVIEST SNOW OVR LUCE CO WILL ALONG THE
LK SHORE. DO NOT XPC THE HVY LES TO REACH INTO N SCHOOLCRAFT AS THE
WNDS WILL BE TOO MUCH OUT OF THE W.

ANOTHER SHRTWV...WEAKER THAN EARLIER ONES...WILL SWING IN W U.P.
OVRNGT. Q-VEC CONVERGENCE WILL INCR ACRS FCST AREA. SFC RDG WILL BE
CNTRD OVR KS. ACYC FLOW WILL KEEP THE WNDS OUT OF THE NW...GRDLY
SHIFTING W. MDLS SHOW A 40KT LOW LVL JET OVR FCST AREA TNGT. WITH
BASE OF THE INVRN ARND 7K FT...MUCH OF THIS WILL WILL MIX TO SFC.
DELTA-TS OVR W LK SUPERIOR WILL BE 20-22C...WHILE OVR THE E IT WILL
BE 22-24C. ETA DEPICTING LOW LVL RH TO BE >80 PCT. 925MB WNDS
SHOWING WEAK CONVERGENCE OVR THE E LK SUPERIOR...WHILE NUETRAL COND
PREVAIL OVR THE FAR W PART OF THE LK. THUS -SHSN WILL CONT OVR FCST
AREA OVRNGT...WITH THE HEAVIEST SNOWFALL OVR E CWA. THUS LOOKING FOR
2 TO 5 INCHES OVR THE E CWA...AND 1 TO 3 OVR NW PART OF CWA.

THE SHRTWV WILL SWING THRU CWA FRI MRNG. Q-VEC INDCT DIVERGENCE ACRS
CWA ON FRI. WND WILL BE MAINLY OUT OF THE W AND REMAIN QUITE STRONG
AND THE MUCH OF LOW LVL JET OVR CWA WILL STILL MIX TO SFC. DELTA-TS
WILL LWR TO 16C OVR MUCH OF LK SUPERIOR. THUS NOT VERY CONDUCIVE FOR
LES OVR E PART OF CWA. LOW LVL MSTR WILL BE ENOUGH TO KEEP SCT -SHSN
GOING...SPCLY IN THE W.

ANOTHER SHRTWV WILL PINWHEEL ARND THE HUDSON BAY LOW AND PASS OVR
FCST AREA FRI NGT. LOOKING FOR INCR IN Q-VEC CONVERGENCE OVRNGT.
DELTA-TS WILL BE ARND 16C. MDLS SHOWING LOW LVL CONVERGENCE...AND
MEAN LOW LVL RH TO INCR TO >80 PCT. WNDS OF THE LOW LVL JET WILL
CONT TO MIX DN AS BASE OF RH WILL BE ABV 850MB. CHC OF SNW LOOKS
LIKELY FRI NGT...TAPERING OFF AFT SHRTWV PASSES.

COORDINATED WITH APX.

.MQT...LAKE EFFECT SNOW WRNG THIS MRNG MIZ005.
       LAKE EFFECT SNOW WARNING TDA AND TNGT MIZ001-003-006-007.
       LAKE EFFECT SNOW ADVY TDA MIZ004.
       GALE WARNING LK SUPERIOR.

DLG