Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 011749
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
149 PM EDT SAT AUG 1 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 447 AM EDT SAT AUG 1 2015

UPPER LAKES REMAINS ON EDGE OF TROUGH ALOFT CENTERED OVER HUDSON
BAY. SFC LOW WITH MSLP DOWN TO 990MB IS LOCATED OVER HUDSON BAY AS
WELL. AREA OF MID CLOUDS WITH A FEW SPRINKLES ARE DROPPING SE ACROSS
WESTERN LK SUPERIOR. EXPECT SCT-BKN CLOUDS...MAINLY THIS AFTN. GOOD
AGREEMENT FM MODELS THAT WEAK LIFT /INCREASED MID-LEVEL RH AND H7-H5
Q-VECTOR CONVERGENCE/ ON SOUTHERN EDGE OF STRONGER SHORTWAVE
CROSSING NORTHERN ONTARIO ALONG WITH LOW-LEVEL CONVERGENCE AND
MLCAPES OVER 500J/KG COULD KICK OFF ISOLD SHRA/TSRA THIS AFTN INTO
EARLY EVENING OVER FAR SOUTHEAST CWA...EAST OF ESCANABA AND SOUTH OF
NEWBERRY. H85 TEMPS 1-2C WARMER BY THIS AFTN COMPARED TO FRIDAY...SO
MAX TEMPS SHOULD TOP OUT IN THE UPPER 70S TO LOWER 80S...WARMEST
SCNTRL. WINDS DO NOT APPEAR TO BE AS STRONG/GUSTY AS FRIDAY...MAINLY
FM THE WNW GUSTING UP TO 15-23 MPH...STRONGEST OVER THE KEWEENAW AND
INTERIOR WEST. RH VALUES WILL BOTTOM OUT IN THE 35-40 PCT RANGE.
GIVEN THE DRY...AND SOMEWHAT DROUGHTISH...PATTERN WE HAVE SETTLED
INTO THE LAST FEW WEEKS...FIRE WEATHER CONCERNS WILL CONTINUE UNTIL
WIDESPREAD MEANINGFUL RAIN IS OBSERVED.

SPEAKING OF RAIN...COULD FIND SOME IN RAIN GAGES BY DAYBREAK ON
SUNDAY. NOT A SURE THING THOUGH. SOUNDINGS FM NAM/GFS SHOW MOISTURE
INCREASING LATE EVENING INTO THE OVERNIGHT HOURS AS ONE SHORTWAVE
APPROACHES FM THE NW ALONG WITH SFC TROUGH AND INCREASING FORCING
AND MOISTURE TRY TO MOVE IN FM THE UPPER MISSISSIPPI RIVER VALLEY.
MOST OF THE MOISTURE THOUGH IS ABOVE H8...MORE IN THE H7-H5 LAYER.
H85 MOISTURE ADVECTION STRONGEST OVER MN AND WI CLOSER TO STRONGER
WSW H85 JET 35-40 KTS. MUCAPE IN LOWEST FEW KM ALSO MAXIMIZED OVER
MN/WI..PERHAPS SOUTHERN PORTIONS. SAMPLING OF MODELS FOR QPF/RAIN
CHANCES RANGE FM MAINLY DRY ECMWF AND GEM...TO GFS WHICH IS THE MOST
GENEROUS. SHOWED INCREASING CHANCES FOR RAIN AS NIGHT GOES ON WITH
THE BETTER CHANCES LATER AT NIGHT WITH ARRIVAL OF LARGER SCALE
FORCING FM NORTHERN STREAM SHORTWAVE AND SFC TROUGH. MUCAPE
MAXIMIZING TO THE SOUTH OF CWA COULD INTERCEPT A LOT OF INSTABILITY
THAT WOULD FEED INTO TSRA. YET...CANADIAN SHORTWAVE SHOWS POTENTIAL
FOR AT LEAST ISOLD TSRA DUE TO COOLER AIR ALOFT...SO KEPT SLIGHT
CHANCES FOR TSRA. LOWS MAINLY IN THE 60S...THOUGH COULD SEE 50S
INLAND WHERE WINDS MAY TRY TO DECOUPLE. WARMEST READINGS WILL BE
CLOSER TO LK SUPERIOR WITH STEADY SW WINDS AHEAD OF THE TROUGH.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 327 AM EDT SAT AUG 1 2015

NAM SHOWS A STRONG 500 MB RIDGE OVER THE ROCKIES WITH TROUGHING
ACROSS THE EAST HALF OF THE U.S. WITH A CLOSED 500 MB LOW OVER
NORTHERN ONTARIO 12Z SUN. THERE IS ALSO A SHORTWAVE OVER LAKE
WINNIPEG 12Z SUN THAT DROPS SOUTHEAST TOWARDS LAKE SUPERIOR ON SUN.
UPPER PATTERN DOES NOT CHANGE MUCH THROUGH 12Z TUE AS UPPER FLOW
CONTINUES FROM THE NW AND AREA REMAINS IN THE UPPER TROUGH. NAM HAS
SOME 850-500 MB Q-VECTOR CONVERGENCE AND DEEPER MOISTURE MOVING
THROUGH ON SUN WITH BOTH MOVING OUT SUN NIGHT.

DID NOT MAKE TOO MANY CHANGES TO THE GOING FORECAST OVERALL. KEPT
CHANCE POPS IN FOR SUNDAY AND HAVE SLIGHT CHANCE POPS IN FOR MON
AFTERNOON WITH SOME DIURNAL CONVECTION POSSIBLE BEFORE NEXT
SHORTWAVE COMES IN FOR LATE MON NIGHT WHEN SLIGHT CHANCE POPS IN
AGAIN. LOWERED TEMPERATURES A COUPLE DEGREES FOR THIS FORECAST
PERIOD AS THE AIRMASS LOOKS COLDER AND SLIGHTLY DRIER THAN BEFORE.

IN THE EXTENDED...GFS AND ECMWF SHOW A 500 MB TROUGH OVER THE GREAT
LAKES REGION AND ANOTHER IN THE PACIFIC NW WITH A BROAD 500 MB RIDGE
ACROSS THE SOUTHERN U.S. 12Z TUE. THE TROUGH AXIS MOVES INTO THE
LOWER GREAT LAKES 12Z WED. TROUGHING STILL REMAINS OVERHEAD 12Z THU.
ECMWF THEN SHOWS THE 500 MB RIDGE BUILDING BACK NORTHWARD INTO THE
PLAINS 12Z FRI WITH SFC RIDGING REMAINING ACROSS THE AREA THROUGH
THIS WHOLE FORECAST PERIOD. TEMPERATURES LOOK TO STAY BELOW NORMAL
FOR THIS FORECAST PERIOD. ANY SHORTWAVE THAT COMES ALONG IN THE
NORTHWEST FLOW IN THE TROUGHING COULD PRODUCE DIURNAL CONVECTION AND
HAVE SOME SLIGHT CHANCE POPS TO COVER THIS FOR THU AND FRI.
&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 148 PM EDT SAT AUG 1 2015

GUSTY WINDS THIS AFTN WL DIMINISH THIS EVNG WITH LOSS OF DAYTIME
HEATING/MIXING. ALTHOUGH A PASSING DISTURBANCE MAY BRING SOME
-SHRA TO UPR MI LATE TNGT...LLVL DRY AIR INDICATES VFR CONDITIONS WL
PREDOMINATE EVEN IF ANY OF THE SHOWERS PASSES OVER ONE OF THE TAF
SITES. THERE WL ALSO BE SOME MARGINAL LLWS OVERNGT WITH A
STRENGTHENING WSW FLOW ABOVE NEAR SFC STABLE LYR. THE APPROACH OF A
STRONGER DISTURBANCE ON SUN WL BRING A BETTER CHC FOR SOME SHOWERS
AND PERHAPS A TS...BUT VFR CONDITIONS SHOULD STILL PREDOMINATE WITH
LINGERING LLVL DRY AIR.
&&

.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 447 AM EDT SAT AUG 1 2015

A LOW SPINNING OVER SOUTHERN HUDSON BAY WILL SWEEP A SERIES OF
TROUGH ACROSS LAKE SUPERIOR THIS WEEKEND. WINDS WILL GENERALLY
REMAIN IN THE 10-20KT RANGE...THOUGH SW WINDS THIS AFTN MAY REACH 20-
25 KTS OVER WESTERN LK SUPERIOR AHEAD AN APPROACHING TROUGH. A BROAD
SURFACE TROUGH WILL MOVE ACROSS THE UPPER GREAT LAKES REGION ON
SUNDAY BEFORE HIGH PRESSURE FROM THE CANADIAN PRAIRIES GRADUALLY
MOVES OVER THE REGION THROUGH MOST OF NEXT WEEK.
&&

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

$$

SHORT TERM...JLA
LONG TERM...07
AVIATION...KC
MARINE...JLA



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