Area Forecast Discussion
Issued by NWS Marquette, MI

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000
FXUS63 KMQT 271913
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
313 PM EDT SAT JUN 27 2015

.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 308 PM EDT SAT JUN 27 2015

PERSISTENT NW FLOW PATTERN ALOFT HAS BEEN AT LEAST TEMPORARILY
INTERRUPTED OVER PARTS OF GREAT LAKES AS STRONGER SHORTWAVE IS
SLIDING OVER THE LOWER GREAT LAKES ALONG WITH SFC LOW NEAR 1000 MB
OVER NORTHERN OHIO. OTHER THAN DAYTIME CUMULUS...HIGH PRESSURE
REMAINS IN CONTROL OVER UPR MICHIGAN. DOES APPEAR THAT POCKET OF
HIGHER MID-LEVEL MOISTURE ALONG WITH DAYTIME HEATING WAS ENOUGH TO
KICK OFF ISOLD SHRA ALONG LAKE BREEZE OVER THE KEWEENAW IN THE LAST
HOUR /ZONE EAST OF KCMX TO NORTHEAST OF TWIN LAKES/. NORTHWEST FLOW
IS PRESENT UPSTREAM OVER SCNTRL CANADA AND THAT IS CARRYING ALONG
VIGOROUS SHORTWAVE AND SFC TROUGH DIGGING ACROSS SOUTHERN MANITOBA
PER 12Z RAOBS AND WV LOOP AND ALSO SEEN FM THE HIGHER COVERAGE TO
SHRA/TSRA JUST AHEAD OF THE WAVE/SFC TROUGH. ISOLD SHRA/TSRA AHEAD
OF THAT WAVE ARE OCCURING AS FAR EAST AS NORTHEAST MINNESOTA TO JUST
NW OF THUNDER BAY ONTARIO.

SHORTWAVE OVER MANITOBA IS FORECAST TO DIG SSE AND STAY WEST OF UPR
MICHIGAN THROUGH SUNDAY AS SHOWN WELL BY TRACK OF H7-H5 Q-VECTOR
CONVERGENCE. SFC TROUGH INTENSIFIES INTO MORE OF A CLOSED SFC LOW
DIVING ACROSS MINNESOTA AND THIS KEEPS HIGHER SFC-H85 THETA-E
WRAPPED UP INTO THE LOW INSTEAD OF ADVECTING TO THE EAST OVER UPR
MICHIGAN. SEEMS THAT RAIN CHANCES EVEN LATE TONIGHT OVER THE WEST
ARE MINIMAL. WILL GO WITH BIAS CORRECTED MIN TEMPS TONIGHT WITH
LIGHT WINDS AND MAINLY CLEAR SKIES. A FEW INLAND LOCALES WILL DROP
INTO THE 40S CNTRL AND EAST.

PER WV LOOP AND H5 RAOBS...THERE IS LIKELY ANOTHER SHORTWAVE OVER
NORTHERN MANITOBA TO NORTH OF THE STRONGER WAVE...AND THAT SECONDARY
WAVE SHOULD TRACK MORE TOWARD LK SUPERIOR AND UPR MICHIGAN ON SUNDAY
AFTN...THUS INCREASING FORCING FOR ASCENT DURING PEAK HEATING. BASED
ON MODEL TRENDS...COULD BE DECENT AMOUNT OF SUNSHINE AHEAD OF THIS
WAVE AND SFC WIND FIELDS APPEAR MORE LAKE BREEZE DRIVEN THAN
ANYTHING ELSE WITH POSSIBLE INTERACTION OF WEAK TROUGH EXTENDING TO
NORTHEAST OF SFC LOW OVER SOUTHEAST MINNESOTA SUNDAY AFTN. AS LONG
AS MID CLOUDS DO STAY WEST...H85 TEMPS ARE UP TO 15C ON THE NAM/GEM-
REGIONAL OVER INTERIOR WEST AT 18Z SUNDAY...SUGGESTING TEMPS MAY
REACH MID 80S THERE AND UPPER 70S TO NEAR 80 AWAY FM ANY LOCALIZED
LAKE BREEZE. MOSTLY EXPECT LOW-MID 50S DWPNTS BUT SEEMS REASONABLE
THAT DWPNTS WILL POOL TOWARD UPR 50S TO AROUND 60 DEGREES ALONG LAKE
BREEZE OVER NORTHWEST CWA IN THE AFTN. NAM AND GEM-REGIONAL SHOW
THIS IDEA. RESULT WILL BE MLCAPES MAINLY IN THE 500-800J/KG RANGE
WITH POCKETS OF NEAR 1000J/KG. GIVEN THE LARGER SCALE LIFT AND LOW-
LEVEL CONVERGENCE ALONG WITH CONVECTIVE TEMPS IN THE MID
70S...EXPECT SHRA/TSRA TO DEVELOP AFTER NOON AND INCREASE IN
COVERAGE BY MID AFTN. COVERAGE SHOULD STAY SCATTERED AT BEST AS
AIRMASS STILL ON THE DRY SIDE.

NOT EXPECTING STRONG STORMS AS DEEP LAYER SHEAR IS VERY WEAK WITH
ONLY 10-20 KTS FORECAST. H85 DWPNTS BARELY REACH 10C IN THE
WEST...SO EVEN THOUGH STORM MOTION WILL BE SLOW...HEAVY RAIN SHOULD
NOT BE AN ISSUE EITHER.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 230 AM EDT SAT JUN 27 2015

IMPACT ASSESSMENT...MOST IMPACTFUL WEATHER WILL BE MON AS SOME
STRONGER THUNDERSTORMS MAY RESULT AND ALSO FRI INTO NEXT WEEKEND DUE
TO INCREASE IN OUTDOOR ACTIVITIES RELATED TO INDEPENDENCE DAY.
GREATEST FOCUS WAS PUT INTO THESE TIMES.

A BROAD UPPER TROUGH WILL BE OVER THE ERN HALF OF THE CONUS SUN
THROUGH MID WEEK. MODELS SHOW A SHORTWAVE MOVING W OF THE CWA ON SUN
AND DRAGGING A SFC TROUGH ALONG WITH IT. FORCING MAY BE SUFFICIENT
FOR SHOWERS AND THUNDERSTORMS MAINLY SUN AFTERNOON/EVENING OVER WRN
UPPER MI. CAPE MAY EXCEED 1000J/KG SUN AFTERNOON/EARLY EVENING...BUT
0-6KM BULK SHEAR VALUES WILL BE LESS THAN 10KTS...SO NO SEVERE
STORMS ARE ANTICIPATED.

SLIGHT CHANCES FOR SHOWERS AND THUNDERSTORMS WILL REMAIN IN THE
FORECAST FOR THE W ON SUN NIGHT AS THE SFC TROUGH SITS OVER WRN
UPPER MI.

TIMING AND TRACK OF A SHORTWAVE MODELS SHOW MOVING THROUGH ON MON
WILL BE IMPORTANT TO CONVECTIVE STRENGTH...ALTHOUGH MOST LOCATIONS
SHOULD AT LEAST SEE PRECIP. WHILE THERE IS SOME UNCERTAINTY...MODELS
GENERALLY SHOW THE SHORTWAVE FIRING CONVECTION STARTING IN THE EARLY
AFTERNOON AND CONTINUE INTO THE EARLY EVENING. CAPE IN EXCESS OF
1000J/KG APPEARS LIKELY IF ENOUGH SFC HEATING CAN RESULT. THE ECMWF
IS ON THE LOW SIDE OF CAPE VALUES WITH SBCAPE AROUND 1000J/KG ALONG
THE WI BORDER...BUT THE NAM AND GFS SHOW 1500-2000J/KG OF SBCAPE IN
THE AFTERNOON. BIG NEGATIVE FOR SEVERE STORMS IS 0-6KM BULK SHEAR
VALUES OF 10-15KTS...SO LAKE BREEZE INTERACTION WILL BE KEY FOR
HAVING ORGANIZED STORMS. WILL NEED TO KEEP AN EYE ON CONDITIONS FOR
MON.

SHOWER AND POSSIBLY THUNDER CHANCES CONTINUE INTO MON NIGHT AS
ANOTHER WEAKER WAVE POSSIBLE MOVES THROUGH. SHOULD SEE CLEARING BY
TUE EVENING AS SFC HIGH PRESSURE PUSHES IN FROM THE N...BUT THERE IS
UNCERTAINTY ON HOW FAST CLEARING OCCURS.

WED THROUGH AT LEAST MOST OF THU LOOK DRY AS A 1020MB HIGH MOVES
THROUGH. IT WILL BE COOLER WITH 850MB TEMPS IN THE MID SINGLE
DIGITS...RESULTING IN HIGHS MAINLY IN THE 60S ON WED.

NOW FOR THE FRI AND SAT TIME PERIOD. MODEL RUN TO RUN CONTINUITY HAS
BEEN POOR ON EXACT TIMING OF A SHORTWAVE AND SUBSEQUENT UPPER TROUGH
LATE IN THE WEEK/NEXT WEEKEND. THE ECMWF HAS A STRONG SHORTWAVE AND
ASSOCIATED WIDESPREAD PRECIP MOVING THROUGH THU NIGHT INTO FRI...THE
GFS IS WEAKER WITH LESS QPF AND LATER (FRI AFTERNOON INTO FRI
NIGHT). BEST IDEA FOR NOW IS CHANCES OF SHOWERS ON FRI. MODELS AGREE
BETTER THAT AN UPPER TROUGH WILL SWING INTO THE AREA ON
SAT...BRINGING QPF INTO THE AREA...ALTHOUGH MODELS DISAGREE ON THE
EXTENT OF THE PRECIP. COOLER AIRMASS MOVES IN WITH THE UPPER TROUGH
SAT INTO SUN...WITH MODELS SHOWING 850MB TEMPS IN THE LOW SINGLE
DIGITS. THE GFS IS SLOWING IN BRINGING IN THOSE COLDER TEMPS...SO
THERE IS UNCERTAINTY THERE AS WELL. THINK PRECIP CHANCES ARE LOWER
ON SAT THAN FRI...WITH SLIGHT CHANCE TO MAYBE LOW CHANCE REASONABLE.
&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 137 PM EDT SAT JUN 27 2015

VFR CONDITIONS AND LIGHT WINDS WILL CONTINUE INTO SUNDAY MORNING.
ISOLATED SHOWERS OR THUNDERSTORMS MAY DEVELOP AT ALL TAF SITES ON
SUNDAY AFTERNOON DUE TO DAYTIME HEATING/INSTABILITY AND APPROACH OF
AN UPPER LEVEL DISTURBANCE. EVEN WITH A SHRA OR TSRA...CONDITIONS ARE
EXPECTED TO REMAIN VFR AT ALL TAF SITES.
&&

.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 308 PM EDT SAT JUN 27 2015

HIGH PRESSURE WILL LEAD TO WINDS STAYING LESS THAN 20KTS REST OF THE
WEEKEND. A SERIES OF WEAK TROUGHS WILL DROP SOUTHEAST ACROSS LAKE
SUPERIOR SUNDAY NIGHT THROUGH EARLY NEXT WEEK BUT WINDS ARE STILL
EXPECTED TO STAY BELOW 20KTS. HIGH PRESSURE BUILDS BACK OVER THE
UPPER GREAT LAKES BY MID WEEK. PATCHY FOG WILL DISSIPATE THROUGH
TONIGHT.

&&

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

$$

SHORT TERM...JLA
LONG TERM...TITUS
AVIATION...JLA
MARINE...JLA



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