Tornado Warning 20, NWS Duluth, MN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DULUTH MN
623 PM CDT TUE JUN 22 2010

.AVIATION...UPDATE FOR 00Z TAFS
VFR CONDS EXPECTED EXCEPT FOR MFVR IN SHRA/TS AND IFR/LIFR IN FG
EARLY WED MRNG. SHOWERS AND TSTMS WILL BE WIDELY SCT...SO IT IS
DIFFICULT TO PREDICT IF ONE WILL FORM WITHIN 5NM OF A TAF
SITE...VCSH AND VCTS WERE USED TO INDICATE THE PSBLTY. THE MOST
LIKELY TIMES WILL BE THIS EVE THRU A FEW HRS AFT MIDNIGHT...THEN
AGAIN WED AFTN.

&&

.PREV DISCUSSION... /ISSUED 249 PM CDT TUE JUN 22 2010/

DISCUSSION...SEVERE CONVECTION IS MAIN FOCUS FOR TONIGHT.

AT 230 PM...MESOSCALE ANALYSIS POINTS TO A COUPLE INTERESTING
FEATURES APPROACHING THE CWA...GENERALLY JUST WEST OF THE CWA AT
THE CURRENT TIME. THE FIRST IS ACROSS NW/NC MN. THERE WERE A FEW
THUNDERSTORMS DEVELOPING ACROSS THIS AREA...GENERALLY RIGHT ALONG
THE INTERNATIONAL BORDER. CIN IS RELATIVELY LOW ACROSS THIS
AREA...AND ALTHOUGH IT IS NOT QUITE AS UNSTABLE AS POINTS
SOUTH...THERE IS SOMEWHAT DECENT FORCING DUE TO THE H5 SHORTWAVE
TROUGH. THE OTHER AREA OF INTEREST IS WC MN WHERE THERE IS A WEAK
FRONT/TROUGH AND NOTED REMNANT MCV/VORT. CLOUDS WERE BECOMING
MORE AGITATED OVER THIS AREA...AS WELL AS ACROSS NW MN.

THE AREA OF WC MN...SPREADING INTO OUR SOUTHERN CWA IS ONE OF
PARTICULAR INTEREST AND SOMETHING WE WILL NEED TO WATCH CLOSELY
OVER THE NEXT COUPLE HOURS. COULD SEE STORMS DEVELOP RAPIDLY IN
THE NEXT HOUR OR SO ACROSS THIS AREA. STABILITY PARAMETERS ARE
QUITE FAVORABLE...AND THIS AREA IS ON THE NORTHERN EDGE OF THE CAP
AND ALONG THE STABILITY GRADIENT AS WELL. MID LEVEL LAPSE RATES
ARE VERY FAVORABLE...AND IT IS HIGHLY UNSTABLE. MU AND ML CAPE
VALUES ARE IN THE 3000-4000 J/KG RANGE AND THERE IS NOTABLE
MOISTURE CONVERGENCE AND FRONTOGENESIS ACROSS THIS REGION. WITH
DEWPOINTS IN THE UPPER 60S TO LOWER 70S...THERE IS PLENTY OF
MOISTURE FOR HP SUPERCELLS. THE MODERATE RISK AREA STILL LOOKS
LIKE IT WILL SEE THE MOST DESTRUCTIVE WEATHER LATER TONIGHT...BUT
UNTIL THEN...THIS MAY BE THE MAIN FEATURE OF INTEREST.

FOR TONIGHT...WILL GENERALLY GO WITH SCATTERED POPS ACROSS THE
CWA. THE RUC AND 4KM NMM WRF BOTH PAINT THE SOUTHERN CWA AS THE
MAIN FEATURE OF INTEREST INTO THE NIGHT...ALONG WITH SOME STORMS
ACROSS THE NORTH AS WELL. WILL NEED TO WATCH FOR RAPID DEVELOPMENT
OF THE STORMS THIS LATE AFTERNOON AND EVENING...WITH THE POTENTIAL
FOR LARGE HAIL...DESTRUCTIVE WINDS AND ISOLATED TORNADOES. SHEAR /
HELICITY IS SLIGHTLY LIMITING ACROSS WC MN...BUT WITH INSTABILITY
BEING VERY HIGH...IT WILL LIKELY BE ABLE TO OVERCOME THIS
POTENTIAL LIMITATION.

FOR WEDNESDAY...THE INTENSE MCS ACROSS SOUTHERN MN AND MUCH OF WI
SHOULD IMPACT MAINLY THE SOUTHERN PORTION OF THE CWA. COULD SEE
SOME SPOTTY SHOWERS AND STORMS NORTH...BUT MAIN ISSUE SHOULD BE IN
THE SOUTH.

WEDNESDAY NIGHT INTO THURSDAY...WILL PROBABLY SEE A DIMINISHING
TREND TO THE PCPN ON WEDNESDAY NIGHT...BUT COULD SEE MORE STORMS
DEVELOPING ON THURSDAY AS A WARM FRONT DEVELOPS ACROSS THE CWA.
HAVE ADDED POPS TO ALL ZONES ON FRIDAY...AS THE POTENTIAL FOR
SHOWERS AND THUNDERSTORMS INCREASES IN THE VICINITY OF THE
FRONT...AND WITH LOW PRESSURE SPREADING IN FROM THE WEST IN THE
AFTERNOON.

EXTENDED...FRIDAY NIGHT THROUGH SATURDAY. LATEST MODEL RUNS
CONTINUE TO SHOW A 30-40 KT SRLY LLJ DEVELOPS OVER THE DAKOTAS/WRN
MN FRIDAY AS BROAD RIDGING IS FOUND OVER NRN PLAINS. TEMPS AT 850
MB INCREASE INTO THE 15-20C RANGE THROUGH FRIDAY NIGHT AS LOW
PRESSURE ADVANCES FROM THE WEST. KEPT BROADBRUSH LIKELY POPS GOING
FOR THIS TIME FRAME AS MOISTURE AND FORCING ARE EXPECTED TO BE
SUFFICIENT FOR CONVECTION OVER MUCH OF THE DLH CWA INTO SAT.
ALTHOUGH GFS/ECM HAVE SIMILAR IDEA THAT A SHORT WAVE DROPS OVER
THE CWA SUNDAY NIGHT/MONDAY...SOLUTIONS DIVERGE GREATLY IN
TIMING/PLACEMENT OF VORT AND QPF. MODELS COME BACK INTO GOOD
AGREEMENT THAT BLOCKING PATTERN SETS UP THROUGH MID WEEK BRINGING
STRONG RIDGING/SFC HIGH PRESSURE TO THE NRN PLAINS AND WRN GRT
LAKES.

AVIATION.../18Z ISSUANCE/
SHOWERS AND THUNDERSTORMS...WITH PERIODS OF MVFR CIGS...WILL BE
FOUND THIS AFTERNOON. STORMS ARE ANTICIPATED TO INITIATE IN
NORTHWEST AND WEST-CENTRAL MINNESOTA ALONG A SURFACE FRONT IN THE
19-21Z TIME FRAME. THE STORMS WILL PUSH EAST INTO WISCONSIN THROUGH
THE EVENING. SOME OF THESE STORMS WILL HAVE THE POTENTIAL TO BE
STRONG TO SEVERE WITH LOCALIZED VARIABLE WIND GUSTS...HAIL...AND
HEAVY RAIN. THE STORMS WILL DIMINISH IN INTENSITY INTO THE NIGHT.

&&

.POINT TEMPS/POPS...
DLH  59  75  55  74 /  40  30  20  10
INL  56  76  52  75 /  30  30  10  10
BRD  61  78  55  79 /  40  30  20  10
HYR  67  82  57  78 /  40  40  20  10
ASX  62  77  57  75 /  40  40  20  10

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...NONE.
&&

04

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE DULUTH MN
331 PM CDT TUE JUN 22 2010

MNZ010>012-018>021-025-026-033>038-WIZ001>004-006>009-231030-
KOOCHICHING-NORTHERN ST. LOUIS-NORTHERN COOK/NORTHERN LAKE-
NORTHERN ITASCA-CENTRAL ST. LOUIS-SOUTHERN LAKE/LAKESHORE-
SOUTHERN COOK/LAKESHORE-NORTHERN CASS-SOUTHERN ITASCA-
SOUTHERN CASS-CROW WING-NORTHERN AITKIN-SOUTHERN AITKIN-
CARLTON/SOUTHERN ST. LOUIS-PINE-DOUGLAS-BAYFIELD-ASHLAND-IRON-
BURNETT-WASHBURN-SAWYER-PRICE-
331 PM CDT TUE JUN 22 2010

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHEAST MINNESOTA AND
NORTHWEST WISCONSIN.

.DAY ONE...THIS AFTERNOON AND TONIGHT

PATCHY DENSE FOG WILL LINGER NEAR LAKE SUPERIOR OVERNIGHT.

SCATTERED THUNDERSTORMS ARE EXPECTED ACROSS THE AREA TONIGHT.
SOME OF THESE THUNDERSTORMS WILL BE SEVERE WITH DAMAGING WINDS
AND LARGE HAIL ACROSS THE ENTIRE AREA. THERE IS ALSO A POSSIBILITY
OF A FEW TORNADOES.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

SCATTERED...MOSTLY AFTERNOON AND EVENING THUNDERSTORMS WILL OCCUR
ACROSS THE AREA WEDNESDAY AND AGAIN FRIDAY THROUGH SUNDAY. AT THIS
TIME...THE THUNDERSTORMS ARE NOT EXPECTED TO BE SEVERE.

.SPOTTER INFORMATION STATEMENT...

SKYWARN SPOTTER ACTIVATION MAY BE NEEDED THIS AFTERNOON AND
TONIGHT.

LSZ121-140>148-231030-
BAYFIELD TO OAK POINT WI-GRAND PORTAGE TO GRAND MARAIS MN-
GRAND MARAIS TO TACONITE HARBOR MN-
TACONITE HARBOR TO SILVER BAY HARBOR MN-
SILVER BAY HARBOR TO TWO HARBORS MN-TWO HARBORS TO DULUTH MN-
DULUTH MN TO PORT WING WI-PORT WING TO SAND ISLAND WI-
SAND ISLAND TO BAYFIELD WI-OAK POINT TO SAXON HARBOR WI-
331 PM CDT TUE JUN 22 2010

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE NEARSHORE WATERS OF
WESTERN LAKE SUPERIOR.

.DAY ONE...THIS AFTERNOON AND TONIGHT

PATCHY FOG WILL LINGER IN THE NEARSHORE AREA OF WESTERN LAKE
SUPERIOR TONIGHT.

SCATTERED THUNDERSTORMS ARE EXPECTED ACROSS THE NEARSHORE WATERS
TONIGHT. SOME OF THESE THUNDERSTORMS WILL BE SEVERE WITH STRONG
WINDS...VERY ROUGH WATER...AND LARGE HAIL. THERE IS ALSO A
POSSIBILITY OF A FEW SIGNIFICANT WATERSPOUTS.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

SCATTERED...MOSTLY AFTERNOON AND EVENING THUNDERSTORMS WILL OCCUR
ACROSS WESTERN LAKE SUPERIOR WEDNESDAY AND AGAIN FRIDAY THROUGH
SUNDAY. AT THIS TIME...THUNDERSTORMS ARE NOT EXPECTED TO BE SEVERE.

DAP

MORE INFORMATION MAY BE OBTAINED AT THE FOLLOWING WEB ADDRESS:
HTTP://WWW.WEATHER.GOV/DULUTH (ALL LOWER CASE)

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