Severe Thunderstorm Warning 45, NWS Marquette, MI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
354 PM EDT MON SEP 11 2000

MAIN FCST CONCERN IS SHRA/TSRA POTENTIAL THIS EVENING.

WV IMAGERY THIS AFTN SHOWS SHORTWAVE TROF MOVING ACROSS DAKOTAS INTO
MN. AT THE SFC...ASSOCIATED COLD FRONT EXTENDS FROM NEAR ISLE ROYALE
TO LOW PRESSURE IN SE MN NEAR KRST. COLD FRONT MAKING STEADY E
PROGRESS. COMBINATION OF TSTMS ACROSS IA/WI/IL DISTURBING INFLOW
INTO UPPER LAKES AND EXTENSIVE LOW CLOUDS ACROSS NW WI/W UPPER MI
INHIBITING STRONG HEATING ARE RESULTING IN DIMINISHED THREAT FOR
SVR TSTMS THIS EVENING.

MODELS IN GOOD AGREEMENT ON FEATURES TO AFFECT UPPER MI. FRONT WILL
CROSS FA THIS EVENING...EXITING E FA BY 06Z. AT THE SAME TIME...
HEALTHY UPPER DIVERGENCE DEVELOPS THIS EVENING AS FA BECOMES IDEALLY
SITUATED UNDER RIGHT ENTRANCE REGION OF 100KT JET RUNNING FROM NE MN
TO JAMES BAY. SO DESPITE LACK OF HEATING...THE COMBINATION OF GOOD
LOW-LEVEL MOISTURE...STRONG LOW-LEVEL CONVERGENCE ALONG FRONT AND
UPPER DIVERGENCE WILL LEAD TO WIDESPREAD COVERAGE OF SHRA/TSRA NEAR
COLD FRONT. IN THE LAST HOUR...SHRA/TSRA HAVE RAPIDLY DEVELOPED
ACROSS NW WI...AND THIS TREND WILL CONTINUE TO DEVELOP NE INTO FA
THIS EVENING. WITH STRONG DRYING AND SUBSIDENCE FOLLOWING FRONT...
SKIES WILL BEGIN TO CLEAR.

850MB THERMAL TROUGH MOVES ACROSS FA ON TUE...AND WITH SFC DWPTS
NEAR OR JUST A LITTLE ABOVE 850MB TEMPS...WILL SEE CU DEVELOP. MAYBE
BKN CU FOR A TIME BEFORE MOISTURE BEGINS TO MIX OUT. SLIGHTLY LOWER
FWC/ETA 2M TEMPS PREFERRED OVER WARMER AVN MOS BASED ON POST FRONTAL
CONDITIONS ACROSS NDAKOTA/S MANITOBA THIS AFTN.

ON WED...A WEAK/DRY COLD FRONT WILL PASS. WITH THERMAL RIDGE ACROSS
AREA...WILL BE A WARMER DAY AND GUIDANCE TEMPS LOOK ACCEPTABLE. ON
THU...SHORTWAVE DIGS SOUTHEAST ACROSS UPPER LAKES. WILL CONTINUE TO
CARRY SHRA CHC AT THAT TIME AS TROF DEEPENS AND INSTABILITY
INCREASES AS COLD POOL ALOFT MOVES OVER UPPER GREAT LAKES.

IN THE EXTENDED...MODELS TRENDING TOWARD A COLD END OF THE WEEK. MRF
IS MOST AMPLIFIED...CLOSING OFF AN UPPER LOW OVER E OHIO VALLEY SAT.
MRF HAS TRENDED TOWARD A MORE AMPLIFIED SOLUTION THIS RUN...AND
MRF ENSEMBLES SHOW GOOD SUPPORT FOR AN AMPLIFIED TROF...BUT NOT
QUITE TO THE EXTENT OF OPERATIONAL RUN. CANADIAN/UKMET AND ECMWF
SHOW SOME MINOR DIFFERENCES IN JUST HOW AMPLIFIED THE TROF WILL
BE...BUT IN ANYCASE...THE OVERALL MESSAGE FROM THE MODELS IS A COOL
FRI/SAT AFTER A CHANCE OF SHRA THU AS SHORTWAVE PASSES. SHOULD BE
PLENTY OF CLOUDS FRI WITH CYCLONIC FLOW AND SUFFICIENT LK-850MB
DELTA-T. FROST/FREEZE A GOOD POSSIBILITY FRI NIGHT WHERE SKIES
CLEAR...PROBABLY INTERIOR CNTRL/W. MRF/ECMWF SHOW NEXT SHORTWAVE
WHICH LOOKS FAIRLY STRONG PASSING SUN...BUT IT WILL BE MOISTURE
STARVED AND SO WILL LEAVE SUN DRY FOR NOW.

.MQT...NONE.

ROLFSON

MIZ001>007-009>014-121000-

SPECIAL WEATHER STATEMENT - SEVERE WEATHER OUTLOOK
NATIONAL WEATHER SERVICE MARQUETTE MI
1215 PM EDT MON SEP 11 2000

...SEVERE THUNDERSTORMS POSSIBLE ACROSS PARTS OF UPPER
MICHIGAN LATE THIS AFTERNOON AND THIS EVENING...

THE NATIONAL WEATHER SERVICE ADVISES THERE IS A RISK OF
SEVERE THUNDERSTORMS LATE THIS AFTERNOON AND EARLY TONIGHT.
DAMAGING WINDS... LARGE HAIL... HEAVY RAIN... AND CLOUD TO
GROUND LIGHTNING ARE POSSIBLE WITH SOME STORMS.

THE GREATEST RISK OF SEVERE STORMS IN UPPER MICHIGAN IS ACROSS THE
FAR SOUTH...IN MENOMINEE COUNTY.  THERE IS A SLIGHT RISK OF SEVERE
THUNDERSTORMS ACROSS THE REST OF UPPER MICHIGAN EAST OF A LINE FROM
BARAGA/L'ANSE TO WATERSMEET. SCATTERED THUNDERSTORMS ARE EXPECTED TO
DEVELOP AROUND 5 PM EDT/4 PM CDT ALONG A FRONT FROM BARAGA TO
WATERSMEET AND MOVE NORTHEAST AT 35 MPH.  SCATTERED THUNDERSTORMS
WILL MOVE FROM SOUTHWEST TO NORTHEAST REACHING CRYSTAL FALLS... IRON
MOUNTAIN AND MENOMINEE AROUND 5 TO 7 PM CDT... AND MARQUETTE AND
ESCANABA AROUND 8 PM EDT.

MONITOR LATER FORECASTS TO KEEP UP WITH THIS WEATHER SITUATION. STAY
TUNED TO NOAA WEATHER RADIO OR THIS STATION FOR THE LATEST
INFmORMATION DIRECT FROM THE NATIONAL WEATHER SERVICE.

ED F