Hail and Damaging Wind in Minnesota, April 17 to 18, 2004

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
330 PM CDT SAT APR 17 2004

.DISCUSSION...
IN PREVIOUS RUNS THERE WAS A GOOD DEAL OF VARIATION AS TO HOW FAR
NORTH THE SURFACE LOW ORGANIZING OVER THE CENTRAL ROCKIES WOULD
TRACK ON SUNDAY. ETA WAS DECIDEDLY FURTHER SOUTH WITH GFS ABOUT 150
MILES NORTH. SOLUTIONS HAVE CONVERGED SOMEWHAT WITH GFS NOT AS FAST
HOWEVER, BOTH MODELS TRACK SURFACE LOW JUST NORTH OF TWIN CITIES.
THIS WILL TAKE SOUTH CENTRAL AND EAST CENTRAL MINNESOTA INTO A WARM
SECTOR THAT IS EXPECTED TO BE DRY SLOTTED.

TONIGHT...STRONG WARM ADVECTION AS DISPLAYED ON 300K ISENTROPIC
SURFACE (BOTH ETA AND GFS) SETS UP ELEVATED CONVECTION. EXPECT A FEW
STORMS MAY PRODUCE SOME LARGE HAIL...GIVEN EXPECTED CAPE LEVELS.
TIMING SUGGESTS AROUND 05Z.

SUNDAY...AS SURFACE LOW CROSSES CENTRAL MN...VERTICAL WIND SHEAR
FORECAST (SFC-70H) TOGETHER WITH SHAPE OF SURFACE THETA-E FIELD AND
CAPE SUGGESTS A DERECHO OR BLOW ACROSS CENTRAL MINNESOTA THAT MAY
VERY WELL INCLUDE THE TWIN CITIES. QPF FORECAST REFLECTS THIS
THINKING.

AFTER THAT...THE COOL AIR PUSHES IN AND WE DRY OUT.

LONGER TERM...TUESDAY NIGHT THROUGH SATURDAY...
THE LATEST GFS MODEL CONTINUES TO INDICATE A SPLIT FLOW OVER NORTH
AMERICA. LONGWAVE TROUGH DAMPENS OVER THE EASTERN GREAT LAKES
EARLIER IN THE PERIOD...ALLOWING WEAK UPPER RIDGE TO BUILD OVER THE
UPPER MIDWEST BY TUESDAY. GFS AND LATEST LONG RANGE MODELS STILL
INDICATE A SERIES OF SHORTWAVE TROUGHS/LOW PRESSURE SYSTEMS MOVING
OVER THE MIDWEST DURING THE WORK WEEK WITH A SIGNIFICANT LOW
PRESSURE SYSTEM MOVING INTO THE MIDWEST OVER THE WEEKEND.
THUS...MORE RAIN ANTICIPATED FOR THE UPCOMING WEEKEND ALONG WITH
SLIGHTLY COOLER TEMPERATURES.
&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.

&&

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
500 AM CDT SAT APR 17 2004

MNZ049-051>053-057>070-073>078-082>085-091>093-WIZ014>016-023>028-
181000-
ANOKA-BARRON-BLUE EARTH-BROWN-CARVER-CHIPPEWA-CHISAGO-DAKOTA-DUNN-
EAU CLAIRE-FARIBAULT-FREEBORN-GOODHUE-HENNEPIN-ISANTI-KANDIYOHI-
LE SUEUR-MARTIN-MCLEOD-MEEKER-NICOLLET-PEPIN-PIERCE-POLK-RAMSEY-
REDWOOD-RENVILLE-RICE-RUSK-SCOTT-SHERBURNE-SIBLEY-ST CROIX-STEARNS-
STEELE-WASECA-WASHINGTON-WATONWAN-WRIGHT-YELLOW MEDICINE-
500 AM CDT SAT APR 17 2004

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF WEST CENTRAL...
EAST CENTRAL AND SOUTH CENTRAL MINNESOTA...AND MUCH OF WEST CENTRAL
WISCONSIN.

.DAY ONE...TODAY AND TONIGHT

THE FIRST SIGNIFICANT SEVERE WEATHER OF SEASON IS POSSIBLE LATER
TONIGHT INTO SUNDAY MORNING. A FRONTAL BOUNDARY THAT HAD STALLED
OVER IOWA THIS MORNING...WILL BEGIN TO LIFT SLOWLY NORTHWARD
TONIGHT. STRONG UPPER LEVEL FORCING ALOFT...COMBINED WITH RETURN FLOW
OF GULF MOISTURE WILL HELP DESTABILIZE THE ATMOSPHERE OVER THE UPPER
MIDWEST DURING THE OVERNIGHT HOURS. THUS...THE NATIONAL STORM
PREDICTION CENTER HAS INDICATED A SLIGHT RISK OF SEVERE STORMS OVER
SOUTH CENTRAL...CENTRAL AND WEST CENTRAL MINNESOTA...AS WELL AS MUCH
OF WEST CENTRAL WISCONSIN FOR LATER TONIGHT.  THE MAIN SEVERE WEATHER
THREATS ARE LARGE HAIL...DAMAGING WINDS AND POSSIBLY A FEW
TORNADOES.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

ANOTHER ROUND OF SEVERE WEATHER IS FORESEEN FOR SUNDAY INTO
SUNDAY NIGHT. A LOW PRESSURE CENTER IS FORECAST TO TRACK
NORTHEAST INTO THE GREAT LAKES BY MONDAY MORNING.  AHEAD OF THIS
WEATHER SYSTEM...SHOWERS AND STRONG THUNDERSTORMS ARE LIKELY TO
REGENERATE ALONG SEVERAL OUTFLOW BOUNDARIES AND NORTH OF THE WARM
FRONT. SOME STORMS COULD PRODUCE LARGE HAIL OR DAMAGING WINDS.
ISOLATED TORNADOES ARE ALSO POSSIBLE WITH A FEW OF THESE STORMS.

GUSTY NORTHWEST WINDS WILL DEVELOP IN THE WAKE OF THE LOW PRESSURE
SYSTEM ON MONDAY.

.SPOTTER INFORMATION STATEMENT...

SKYWARN SPOTTER ACTIVATION COULD BE NEEDED LATER TONIGHT.

MNZ041>045-047-048-050-054>056-181000-
BENTON-CHIPPEWA-DOUGLAS-KANABEC-LAC QUI PARLE-MILLE LACS-MORRISON-
POPE-STEVENS-SWIFT-TODD-
500 AM CDT SAT APR 17 2004

THIS HAZARDOUS WEATHER OUTLOOK IS FOR A PORTION OF WEST CENTRAL
AND CENTRAL MINNESOTA.

.DAY ONE...TODAY AND TONIGHT

SCATTERED THUNDERSTORMS MAY DEVELOP LATER TONIGHT.  A FEW OF THESE
STORMS MAY PRODUCE LARGE HAIL OR DAMAGING WINDS.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

A FRONTAL BOUNDARY THAT HAS STALLED OVER IOWA...WILL BEGIN TO LIFT
NORTHWARD INTO NORTH CENTRAL MINNESOTA BY SUNDAY EVENING.
MEANWHILE...A LOW PRESSURE SYSTEM TRACKING ALONG THE FRONT...WILL
ADVANCE INTO WEST CENTRAL MINNESOTA SUNDAY NIGHT...THEN MOVE RAPIDLY
NORTHEAST INTO THE GREAT LAKES REGION BY MONDAY MORNING. THERE
REMAIN A THREAT FOR SEVERE WEATHER OVER PARTS OF WEST CENTRAL
AND CENTRAL MINNESOTA SUNDAY AFTERNOON AND SUNDAY EVENING. THE MAIN
SEVERE WEATHER THREATS ARE LARGE HAIL AND DAMAGING WINDS. AN ISOLATED
TORNADO IS POSSIBLE SUNDAY AFTERNOON AND SUNDAY EVENING.

STRONG NORTHWEST WINDS MAY DEVELOP BEHIND THE LOW PRESSURE ON
MONDAY.

.SPOTTER INFORMATION STATEMENT...

SKYWARN SPOTTER ACTIVATION MAYBE NEEDED LATER TONIGHT.