Severe Thunderstorm Warning 9, NWS Marquette, MI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
405 PM EDT THU MAY 17 2001

MAIN FORECAST CONCERNS DEAL WITH PCPN/CONVECTION/WIND THIS
EVENING...THEN MAX TEMPS ON FRI AND SAT.

LATEST OBSERVATIONS AND SATELLITE PICTURES SHOW A WEAK SURFACE
TROUGH JUST TO THE WEST OF IRONWOOD. VERY LITTLE MOISTURE ASSOCIATED
WITH THIS SYSTEM DUE TO MOST OF THE DEEP MOISTURE BEING LOCKED UP IN
THE CENTRAL/SRN PLAINS SYSTEM. KMQT 88D INDICATE A FEW CELLS
DEVELOPING NEAR THE TROUGH AXIS OVER THE WESTERN U.P. WITH THE BEST
CONVECTIVE ACTIVITY SEEN IN NORTHEAST MN UNDER THE -23C H5 COLD
POOL. THE ETA DID AN EXCELLENT JOB PEGGING THE CONVECTION OVER NE MN
THIS AFTN...AND THAT MODEL INDICATES THAT THERE MAY BE A CHANCE OF
SHRA/TSRA THIS EVENING. ETA SHOWS WEAK LOW LEVEL CONVERGENCE AND
SOME MARGINAL CAPE OVER THE CENTRAL AND EASTERN U.P THIS
EVENING...AND WITH SHOWERS/TSRA ALREADY OVER WESTERN LAKE
SUPERIOR...IT WOULD BE PRUDENT TO INCLUDE SCATTERED/ISOLATED POPS
ACROSS THE NORTH AND EAST.

CONCERNING THE WINDS...OBSERVATIONS FROM THE AREA AND UPSTREAM SHOW
WINDS IN THE BREEZY CATEGORY DUE TO SOME STEEP LOW LEVEL LAPSE RATES
AND DECENT MIXING. BUFKIT SOUNDINGS FROM THE WESTERN U.P. SHOW THE
MIXING AND BREEZY CONDITIONS TO CONTINUE THROUGH ABOUT 10 PM AND
THEN WEAKEN AS THE LOWER LEVELS STABILIZE.

FRIDAY SHOULD BE A SUNNY DAY ACROSS THE ENTIRE FA WITH HIGH PRES
BUILDS INTO THE AREA...WITH THE H5 RIDGE AXIS BUILDING OVERHEAD.
ONLY PROBLEM WILL BE THE MAX TEMPS AND THE SEA BREEZE POTENTIAL
ALONG THE LAKES. WITH HIGH PRES BUILDING INTO WISCONSIN...GRADIENTS
ARE GENERALLY LIGHT WITH THE EXCEPTION OF THE EASTERN FA. THIS
SHOULD CAUSE THE SEA BREEZE TO PENETRATE INLAND ACROSS THE SUPERIOR
SHORELINE. THE MODELS SHOW NWLY 10 TO 20 KT LOWER LEVEL WINDS ACROSS
DELTA AND SCHOOLCRAFT COUNTIES...WHICH MAY PREVENT THE LAKE BREEZE
FROM MOVING ONSHORE UNTIL VERY LATE AFTN. WILL THEREFORE RAISE MAX
TEMPS SLIGHTLY ALONG LAKE MICHIGAN. OTHERWISE...INLAND TEMPS SHOULD
RISE WELL INTO THE MID 70S WITH H8 TEMPS AROUND +8C WITH PLENTY OF
SUNSHINE.

ON SATURDAY...WILL GO WITH AN INCREASING CLOUDS TREND AS THE NEXT
WEAK SYSTEM MOVES OUT OF THE CANADIAN PRAIRIES AND MOVES RAPIDLY
EAST. BEST DYNAMICS AND LIFT STAY WELL NORTH OF THE AREA SO IT IS
MARGINAL WHETHER OR NOT IT WILL RAIN ON SAT NIGHT. HOWEVER...ENOUGH
MOISTURE AND LIFT ARE AROUND TO WARRANT SOME MENTION OF POPS FOR SAT
NIGHT. IT LOOKS LIKE SUNDAY MAY HAVE A SLIGHTLY BETTER CHANCE AS A
WEAK SHORT WAVE MOVES OVER THE AREA.

FOR THE EXTENDED...FOLLOWING THE WEAK SYSTEM THAT MOVES THROUGH THE
NORTHERN GREAT LAKES SATURDAY NIGHT AND SUNDAY...THE MODEL START TO
DIVERGE ON THE STRENGTH AND LOCATION OF THE NEXT SYSTEM MOVING OUT
OF BRITISH COLUMBIA AND INTO THE GREAT LAKES STATES MONDAY NIGHT AND
BEYOND. THE MODELS ARE IN GENERAL AGREEMENT IN MOVING A STRONG SHORT
WAVE OUT OF ALBERTA SUNDAY AND MOVING IT INTO THE NRN PLAINS SUN
NIGHT WHILE CLOSING AN UPPER LOW OFF OVER NORTH DAKOTA. AFTER THIS
THE MODELS DIVERGE AS THE MRF MOVES THE LOW SOUTHWEST AND NEARLY
CUTS IT OFF FROM THE NRN STREAM...WHILE THE UKMET/EURO/CANADIAN KEEP
THE SYSTEM A LITTLE MORE PROGRESSIVE AND MUCH FURTHER N INTO CANADA.
REGARDLESS...IT LOOKS LIKE TUESDAY WILL BE A WET DAY ACROSS THE AREA
AS THE AVN BRINGS PWATS TO 1.6 INCHES AND KI/S TO 35C. AGREE WITH
NCEP/S MAN PROGS WHICH KEEP THE SYSTEM A LITTLE MORE
PROGRESSIVE...SO THU MIGHT END UP BEING DRY. WILL ALSO HIGHLIGHT
SOME WIND FOR TUE AND WED AS LOW DEEPENS TO 999 MB AND MOVES JUST TO
THE N OF THE AREA.

COORD WITH APX...THANKS!

.MQT...NONE.

MRD