Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 031940
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
340 PM EDT SUN MAY 3 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 505 AM EDT SUN MAY 3 2015

WV IMAGERY AND RUC ANALYSIS INDICATED A BROAD SHALLOW MID/UPPER
LEVEL TROUGH OVER WRN CANADA...FROM BC INTO NW ONTARIO. A SHORTWAVE
TROUGH AND ASSOCIATED SFC LOW WAS LIFTING NE FROM FAR NW ONTARIO TO
TOWARD HUDSON BAY WHILE ANOTHER UPSTREAM SHRTWV WAS MOVING INTO SRN
MANITOBA. AT THE SFC...SSW FLOW WAS INCREASING THROUGH THE UPPER MS
VALLEY INTO THE WRN LAKES AHEAD OF A COLD FRONT STRETCHING FROM NW
MN INTO ERN SD. SCT SHRA AND ISOLD TSRA HAD DEVELOPED AHEAD OF THE
FRONT OVER CNTRL INTO NE MN WITH FAVORABLE 925 MB THETA-E ADVECTION.
UPSTREAM DEWPOINTS FROM MN INTO NW WI HAD CLIMBED TO AROUND 50.

A SHORTWAVE TROUGH AND ASSOCIATED COLD FRONT WILL SLIDE THROUGH THE
NRN GREAT LAKES LATE THIS AFTERNOON AND TONIGHT. MOISTURE IS
EXPECTED TO INCREASE AHEAD OF THE FRONT WITH 850 MB DEWPOINTS NEAR
10C...SFC DEWPOINTS INTO THE LOWER 50S AND PWAT VALUES TO AROUND
1.25 INCH. EVEN WITH INCREASING CLOUDS...WAA WILL HELP PUSH TEMPS
INTO THE MID TO UPPER 70S OVER THE WEST HALF.

THE COMBINATION OF WEAK TO MODERATE 700-500 MB QVECTOR CONV AHEAD OF
THE SHRTWV AND LOW LEVEL CONV ALONG AND AHEAD OF THE FRONT WILL
SUPPORT SCT/NUMEROUS SHRA/TSRA INTO THE WEST HALF OF UPPER MI BY MID
TO LATE SUN AFTERNOON AND ACROSS THE REST OF THE CWA SUN EVENING.
LAKE BREEZE BOUNDARIES WILL ALSO PROVIDE A FOCUS FOR TSRA
DEVELOPMENT. MLCAPE LIKELY TO AROUND 1K J/KG DURING PEAK AFTERNOON
HEATING ALONG WITH 0-6KM SHEAR OF 30-35KT AND WBZERO HEIGHTS OF 9K-
10K FT MAY BE ENOUGH TO SUPPORT SOME ISOLD SEVERE STORMS WITH
DAMAGING WINDS AND LARGE HAIL...MAINLY OVER THE SW CWA WHERE THE
INSTABILITY IS EXPECTED TO GREATEST. THERE IS STILL SOME UNCERTAINTY
WITH THE SEVERE RISK INTO UPPER MICHIGAN AS NAM REMAINS MORE
AGGRESSIVE WITH THE AMOUNT OF MLCAPE AVAILABLE COMPARED TO THE
ECMWF/GFS/GEM WHICH KEEP THE GREATER MOISTURE/INSTABILITY FARTHER
SOUTH.

EXPECT MOST OF THE SHRA/TSRA TO MOVE SOUTH AND EAST OF THE CWA BY
06Z WITH SOME LINGERING PCPN OVER THE FAR S AND E LATE.

.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 300 PM EDT SUN MAY 3 2015

THE MODELS INDICATE THAT THE NRN STREAM ZONAL FLOW WILL GIVE WAY TO
RIDGING OVER THE WRN GREAT LAKES DOWNSTREAM FROM A TROUGH DEVELOPING
OVER THE WRN CONUS. BY LATE IN THE WEEK...SHORTWAVES EMERGING FROM
THE SW CONUS AND CNTRL PLAINS WILL HELP TO FLATTEN THE RIDGE AND
BRING AN INCREASING POTENTIAL FOR PCPN INTO THE WRN GREAT LAKES.
TEMPS ARE EXPECTED TO REMAIN ABOVE NORMAL THROUGH MUCH OF THE
PERIOD.

HIGH PRES WILL DOMIMATE KEEPING CONDITIONS DRY MON NIGHT THROUGH
TUE. WITH PWATS DROPPING DOWN BLO .25 INCH AND LIGHT WINDS EXPECTED
UNDER THE SFC HIGH...MIN TEMPS MON NIGHT COULD VERY WELL DROP BELOW
FREEZING AT SEVERAL OF THE TYPICAL INLAND COLD SPOTS. EXPECT TEMPS
TO REBOUND ON TUESDAY AND MAYBE BE A FEW DEGREES WARMER THAN
MONDAY/S READINGS...WITH HIGHS IN THE 60S AND LOWER 70S...WARMEST
WEST. COOLER READINGS IN THE 50S CAN BE EXPECTED NEAR THE GREAT
LAKES...ESPECIALLY NEAR LAKE MICHIGAN WITH DEVELOPING LIGHT SE FLOW
ON BACKSIDE OF SFC RIDGE AXIS.

TUE NIGHT-WED NIGHT...INCLUDED SOME LOW POPS FOR SHRA OVER MAINLY
WEST HALF (ESPECIALLY ALONG THE WI BORDER) WHICH MAY DEVELOP LATE
TUE NIGHT INTO WED ALONG AN 850 MB WARM FRONT LIFTING SLOWLY NNE
FROM THE UPPER MS VALLEY AND AHEAD OF A STRENGTHENING 850 MB JET
NOSING INTO THE WRN GREAT LAKES. TEMPS WILL BEGIN TO INCREASE WED
WITH WAA BUT THERE COULD BE SOME WAA CLOUDS AROUND TO KEEP TEMPS
DOWN A BIT. MODELS SUGGEST A LULL IN PCPN WED NIGHT AS 850 MB WARM
FRONT LIFTS NORTH OF THE AREA AND WRN GREAT LAKES REGION BECOMES
CAPPED BY WARMER/DRIER AIR ALOFT.

THU-FRI...TEMPS SHOULD REALLY CLIMB THU ALONG WITH INCREASING GULF
MOISTURE IN STRENGTHENING SRLY FLOW AHEAD OF A PLAINS SFC TROUGH
THAT WILL EDGE TOWARD THE UPPER MS VALLEY. LAYER PWATS INCREASE FROM
NEAR 1.5 INCHES WEST TO 1.25 INCHES EAST. MODELS STILL DIFFER ON
TIMING OF COLD FRONTAL PASSAGE LATE IN THE WEEK WITH THE 00Z ECMWF
12-18 HRS FASTER THAN EITHER THE 12Z GFS OR 12Z CANADIAN MODEL. 00Z
ECMWF HAS FRONT MOVING THROUGH LATE THU NIGHT AND FRI WHILE THE 12Z
GFS/CANADIAN SHOW A FRONTAL TIMING OF FRI ATFERNOON AND FRI NIGHT.
ALL MODELS SHOW INCREASING PCPN CHANCES OVER THE WEST HALF THU
AFTERNOON SPREADING INTO THE EAST HALF THU NIGHT AHEAD OF
APPROACHING FRONTAL BOUNDARY. MOST OF THE MODELS SHOW SHRA/TSRA
HANGING AROUND ON FRIDAY WITH ECMWF SHOWING FRONTAL PASSAGE TAKING
PLACE AND GFS/CANADIAN SHOWING FRONTAL BOUNDARY APPROACHING THE WRN
CWA.

FRI NIGHT-SATURDAY...MODEL DIFFERENCES WILL HAVE BIGGEST IMPACT ON
FCST TOWARD NEXT WEEKEND. IF 00Z ECMWF VERIFIES THEN FRI NIGHT AND
SAT WILL BE MOSTLY DRY AND COOLER IN WAKE OF FRONTAL PASSAGE. THE
12Z SLOWER GFS AND CANADIAN SOLN WITH FRONT WOULD WARRANT KEEPING
SHRA/TSRA CHCS IN FOR AT LEAST THE CENTRAL AND ERN FCST AREA FRI
NIGHT AND MAYBE EVEN LINGERING INTO SAT MORNING. GFS AND CANADIAN
WOULD THEN ARGUE FOR DRIER/COOLER CONDITIONS SAT AFTERNOON INTO SAT
NIGHT AS HIGH PRES BUILDS IN FM THE NW IN THE WAKE OF THE FRONTAL
PASSAGE. GIVEN POOR MODEL AGREEMENT WILL PROBABLY EMPLOY A BLEND
OF FCST GUIDANCE FOR POPS DURING THIS PERIOD.

NEXT SUNDAY...AGAIN MODEL DIFFERENCES WILL PROBABLY ARGUE FOR USING
A BLEND OF MODEL GUIDANCE BY DAY 7 FCST. THIS WOULD WARRANT A DRY
FCST FOR MUCH OF THE CWA ESPECIALLY CENTRAL AND EAST STILL UNDER
INFLUENCE OF CANADIAN HIGH PRES OVER AREA. THE ECMWF SHOWS SYSTEM
DEVELOPING OVER CENTRAL PLAINS AND TRIES TO DEVELOP PCPN ALONG THE
WI BORDER COUNTIES IN STRENGTHENING WAA PATTERN OUT AHEAD OF IT.
&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 151 PM EDT SUN MAY 3 2015

EXPECT MAINLY VFR CEILINGS/VIS THROUGH THE PERIOD. THE ONLY
EXCEPTION WILL BE IF AND WHEN TS ENTER THE AREA. SHOWERS AND
ISOLATED TS ACTIVITY ACROSS CENTRAL MN WILL CONTINUE TO EDGE
NE...WITH ADDITIONAL SHOWERS AND TS DEVELOPMENT ALONG THE NEARING
COLD FRONT STRETCHING FROM SE ACROSS CENTRAL MANITOBA TO NEAR THE W
LAKE SUPERIOR SHORELINE...AND THROUGH CENTRAL MN. LOOK FOR THE BEST
CHANCE FOR TS DEVELOPMENT AT IWD 20-22Z. WHILE SAW WILL HAVE A
CHANCE OF TS AROUND 23Z...IT WAS LESS LIKELY...SO LEFT VCTS OUT OF
THE TAF FOR THEM. DRY HIGH PRESSURE ROLLING INTO E MT AND THE
DAKOTAS THIS AFTERNOON WILL QUICKLY BUILD IN BEHIND THE FRONT. THE
RESULT WILL BE A CLEAR/MOSTLY CLEAR BY DAYBREAK MONDAY IF NOT
EARLIER.
&&

.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 339 PM EDT SUN MAY 3 2015

OUTSIDE OF ANY THUNDERSTORM ACTIVITY...WINDS ACROSS LAKE SUPERIOR
SHOULD BE AROUND 25KTS OR LESS THROUGH THE PERIOD.

A LOW OVER S HUDSON BAY WILL MOVE INTO FAR N QUEBEC TONIGHT AND DRAG
A TROUGH/COLD FRONT OVER LAKE SUPERIOR...WITH SHOWER AND
THUNDERSTORMS...AND THE POTENTIAL FOR AREAS OF FOG. FOG WILL LINGER
INTO MONDAY OVER THE E HALF OF LAKE SUPERIOR. IN THE WAKE OF THE
TROUGH...HIGH PRESSURE WILL BUILD OVER THE UPPER LAKES FROM THE W-NW
ON MONDAY. EXPECT THIS HIGH TO DRIFT INTO SE ONTARIO LATER TUESDAY
INTO WEDNESDAY...AS ANOTHER AREA OF HIGH PRESSURE MOVES INTO NW
ONTARI...AND A LOW TAKES SHAPE OVER THE PLAINS. A LOW PRESSURE
CENTER EMERGING FROM THIS TROUGH WILL MOVE THROUGH THE N PLAINS ON
THURSDAY WHILE THE ONTARIO HIGH DRIFTS ACROSS HUDSON BAY INTO
QUEBEC. THE LOW WILL DRAG A TROUGHACROSS THE UPPER GREAT LAKES
REGION THURSDAY NIGHT THROUGH FRIDAY.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&

$$

SHORT TERM...JLB
LONG TERM...VOSS
AVIATION...KF
MARINE...KF



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