Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 040749
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
349 AM EDT TUE AUG 4 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 303 AM EDT TUE AUG 4 2015

UPPER AIR PATTERN CONSISTS OF A DEEP 500 MB TROUGH OVER THE EAST
HALF OF NORTH AMERICA WITH A CLOSED LOW OVER CENTRAL ONTARIO. UPPER
FLOW CONTINUES TO BE FROM THE NORTHWEST AND THE TROUGH AXIS WILL
SLOWLY MOVE EAST THIS FORECAST PERIOD.

WITH TROUGHING AND A WEAK SHORTWAVE PASSING THROUGH THE AREA
TODAY...KEEPING SLIGHT CHANCE POPS IN CONTINUES TO LOOK GOOD AND
WILL KEEP IN THE FORECAST. WILL CONTINUE A DRY FORECAST FOR TONIGHT.
OVERALL...DID NOT MAKE TOO MANY CHANGES TO THE GOING FORECAST FOR
TEMPERATURES. CLOUDS WILL SLOWLY DECREASE TODAY AND WITH MOSTLY
CLEAR SKIES AND LIGHT WIND TONIGHT...GOOD RADIATIONAL COOLING
CONDITIONS SET UP.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 347 AM EDT TUE AUG 4 2015

UPPER TROUGH OVER EASTERN CANADA SLOWLY LOSES ITS INFLUENCE ON THE
WEATHER OVER GREAT LAKES BY MID WEEK. FLOW BECOMES ZONAL ENOUGH LATE
IN THE WEEK TO ALLOW A COUPLE OF SHORTWAVE TROUGHS TO MAKE IT OVER
THE UPPER GREAT LAKES. TREND IS FOR BETTER CHANCES OF RAIN THURSDAY
INTO FRIDAY...THOUGH EXTENT AND INTENSITY OF SHRA/TSRA WILL DEPEND
ON TRACK OF INDIVIDUAL CONVECTIVE SYSTEMS...ESPECIALLY FRIDAY AND
FRIDAY NIGHT.

UPPER LAKES STILL WITHIN WESTERN EDGE OF TROUGH ALOFT ON WEDNESDAY.
WEAK SHORTWAVE WORKS THROUGH...BUT STRONGER H8-H7/H7-H5 Q-VECTOR
CONVERGENCE STAYS SOUTH OF CWA. ANOTHER STRONGER SHORTWAVE WILL BE
CROSSING DAKOTAS IN THE AFTN...BUT MAIN FORCING SHOULD STAY WEST OF
CWA THROUGH PEAK HEATING OF THE DAY. NAM SHOWS A BIT MORE MOISTURE
IN THE H85-H8 LAYER WITH MINOR LESS THAN 50 J/KG OF CAPE. CONVECTIVE
TEMPS FM THE NAM ARE IN THE 60S. GFS IS DRIER AND SHOWS MORE CAPPING
WITH CONVECTIVE TEMPS OVER 80 DEGREES. SUSPECT NAM MAY BE OUTLIER IN
SHOWING BETTER CHANCE FOR SHRA...BUT WILL GO AHEAD AND KEEP SLIGHT
CHANCES IN OVER CNTRL CWA WITH LAKE BREEZE CONVERGENCE. A VERY SMALL
CHANCE. PROBABLY LOOKING AT SPRINKLES MORE THAN ANYTHING ELSE. TEMPS
WILL BEGIN TO REBOUND WITH READINGS IN THE UPR 60S TO LOW 70S.

DAKOTAS SHORTWAVE AND WEAK LIFT MOVE EAST ACROSS UPR MICHIGAN WED
NIGHT INTO THURSDAY MORNING. SOUNDINGS SUGGEST LGT SHOWERS ARE
POSSIBLE DUE TO A LOT OF MID-LEVEL MOISTURE WITH AT LEAST WEAK LIFT
IN THAT MOIST LAYER. ELEVATED CAPE IS MINIMAL...SO THOUGH DID GO
WITH CHANCE POPS...KEPT TSRA OUT FOR NOW. AT THE LEAST...TEMPS WILL
BE HELD DOWN TO WHAT COULD BE REALIZED WITH CONTINUAL H85 WARMING.
ANOTHER SHORTWAVE SLIDES OUT OF THE DAKOTAS BY THURSDAY NIGHT THEN
ACROSS UPPER GREAT LAKES ON FRIDAY. SFC LOW ACCOMPANIES THE TROUGH
ALOFT WHICH WILL RESULT IN GREATER CHANCE THAT ELEVATED INSTABILITY
WILL BE PROPELLED FAR ENOUGH NORTH AND EAST TO BRING SHRA/TSRA OVER
AT LEAST PARTS OF CWA. GRADIENT OF MUCAPE STAYS SOUTHWEST OF CWA AND
SINCE THE SHORTWAVE MOVING IN IS NOT STRONG AND WITH SFC RIDGE IN
PLACE OVER ONTARIO AND THE LOWER GREAT LAKES...BETTER CHANCES FOR
SHRA/TSRA THURSDAY NIGHT INTO FRIDAY MAY STAY WEST OR SOUTHWEST OF
CWA. WILL CARRY CHANCES FOR SHRA WITH ONLY SLIGHT CHANCES FOR TSRA.

STRONGER SHORTWAVE TROUGH...POSSIBLY MORE CLOSED OFF...ALONG WITH
CLOSED OFF SFC LOW CROSS UPPER GREAT LAKES SATURDAY AND SATURDAY
NIGHT. INSTABILITY GREATER THAN THURSDAY OR FRIDAY WITH MUCAPE OVER
1000J/KG PUSHING INTO SOUTHERN CWA. DUE TO THE STRONGER SHORTWAVE
THE EFFECTIVE SHEAR OVER 35-40 KTS WOULD SUPPORT ORGANIZED TSRA. H85-
H3 MEAN WINDS POINT TO SCNTRL CWA BEING MOST FAVORED FOR STRONGER
STORMS. INCREASED CHANCES FOR TSRA TO CHANCE CATEGORY...BUT WILL NOT
PUT ANY KIND OF ENHANCED TSRA WORDING IN HAZARDOUS WEATHER OUTLOOK
DUE TO POOR CONSISTENCY FM MODELS ON SOLUTIONS FOR NEXT WEEKEND.
APPEARS THAT TROUGH ALOFT AND SFC LOW WILL MAINLY BE EAST OF CWA BY
SUNDAY...SO THERE MAY BE A LULL IN ANY SHRA/TSRA. CONSENSUS SHOWS
UPTICK IN SHRA/TSRA CHANCES SUNDAY NIGHT INTO MONDAY...BUT THIS IS
BEING BIASED BY 12Z ECMWF WHICH DID SHOW SOMETHING SIMILAR. 00Z RUN
OF ECMWF AND GFS NOT NEAR AS BULLISH WITH THIS IDEA. THIS JUST
SPEAKS TO THE INCONSISTENCY IN THE MODEL SOLUTIONS FOR NEXT WEEKEND
WITHIN QUICKER WESTERLY FLOW PATTERN ALONG NORTHERN EDGE OF BROAD
RIDGE OVER SOUTHERN PLAINS.
&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 121 AM EDT TUE AUG 4 2015

EXPECT QUITE A BIT OF LOW CLOUDS TO LINGER THRU THE MORNING AS THE
UPPER GREAT LAKES WILL BE DOMINATED BY A MOIST CYCLONIC NW FLOW
AROUND LOW PRES NEAR HUDSON BAY. ALTHOUGH VFR CONDITIONS SHOULD BE
THE RULE FOR THE MOST PART AT KIWD/KCMX/KSAW...CIGS MAY DROP INTO
THE HIGH END MVFR RANGE AROUND SUNRISE GIVEN CURRENT OBS UPSTREAM TO
THE NW OF LAKE SUPERIOR. EVEN IF CIGS DROP INTO THE MVFR CATEGORY...
DAYTIME HEATING AND LOW-LEVEL DRYING WILL ALLOW A RETURN OF VFR
CONDITIONS AT ALL TERMINALS BY LATE MORNING. UNDER DEEPER DRYING
DURING THE AFTN...EXPECT CLOUDS TO SCATTER OUT AT ALL TERMINALS.
WHILE ISOLD -SHRA AND/OR SPRINKLES ARE EXPECTED AT TIMES INTO THE
MORNING HRS...VFR VIS SHOULD PREVAIL.
&&

.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 303 AM EDT TUE AUG 4 2015

EXPECT WNW WINDS UP TO 20 KTS INTO MID WEEK AROUND DEEP LOW PRESSURE
NEAR HUDSON BAY. A WEAK PRESSURE GRADIENT WILL DOMINATE DURING THE
LATE WEEK...RESULTING IN WINDS UNDER 20 KTS. NO GALES SEEN ANYTIME
SOON.
&&

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

$$

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



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