Area Forecast Discussion
Issued by NWS Marquette, MI

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000
FXUS63 KMQT 062320
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
720 PM EDT WED MAY 6 2015

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 349 PM EDT WED MAY 6 2015

UPPER RIDGE IN PLACE OVER UPPER LAKES CURRENTLY THOUGH A TROUGH IS
BEGINNING TO EJECT NORTHEAST ACROSS THE PLAINS THIS AFTN. WARM AND
MOIST ADVECTION ALOFT IS SUPPORTING BAND OF CLOUDS AND ISOLD SHRA OR
SPRINKLES OVER NORTHERN WI INTO MAINLY WESTERN UPR MICHIGAN. AWAY FM
THOSE CLOUDS THOUGH SFC HIGH OVER EASTERN ONTARIO IS THE MAIN
WEATHER FEATURE. DEEP MIXING INTO VERY DRY AIR ALOFT BENEATH THE
HIGH RESULTED IN VERY LOW RH OVER THE EAST CWA WITH VALUES AS LOW AS
11 PCT AT KERY AT 3 PM EDT. QUITE THE SPREAD IN RH ACROSS UPR
MICHIGAN THIS AFTN FM WEST TO EAST. FOR TONIGHT...MID CLOUDS AND
SOME SHRA MAY AFFECT MOSTLY WEST CWA THIS EVENING. OVERNIGHT SOUTH
RETURN FLOW FORMING BTWN THE SFC HIGH AND LOW PRESSURE TROUGH OVER
PLAINS MAY RESULT IN LOW CLOUDS TRYING TO FORM OVER CNTRL UPR
MICHIGAN. IF THIS OCCURS...FLOW TURNING MORE SSW ON THURSDAY MORNING
AND DRY AIR MAINLY ABOVE H85 SHOULD ALLOW THE CLOUDS TO QUICKLY
ERODE. MID CLOUDS WILL BE INCREASING FM THE WEST THROUGH THE DAY.

TEMPS ALOFT BECOME MUCH WARMER THAN TODAY WITH +13C TO +15C AT H85
BY THU AFTN. SOUNDINGS SHOW POTENTIAL FOR WARM AIR ALOFT TO RESULT
IN WEAK SUBSIDENCE INVERSION BUT THINK DEEPER MIXING SHOULD LEAD TO
BEING ABLE TO TAP INTO SOME OF THE WARM AIR ALOFT...BOOSTING AFTN
TEMPS INTO UPR 70S OR LOW 80S. WINDS ALOFT INCREASE LATE TONIGHT
INTO THURSDAY...WITH H85 WINDS UP TO 40 KTS BY THU AFTN. COULD GET
QUITE GUSTY IF THERE IS EVEN PARTIAL SUNSHINE. WENT WITH GUSTS 30-40
MPH IN THE AFTN ON THURSDAY. SHRA/TSRA SHOULD STAY MAINLY WEST OF
UPR MICHIGAN ALONG AXIS OF GREATER H85-H7 MOISTURE TRANSPORT...BUT
SHRA AND SOME TSRA SHOULD BEGIN TO EXPAND OVER WESTERN CWA 18Z-24Z
AS SHORTWAVE CURRENTLY OVER WESTERN KS LIFTS ACROSS MN AND WESTERN
LK SUPERIOR AND SFC FRONT AND ASSOCIATED WARM AIR ADEVECTION AHEAD
OF IT DRAW CLOSER. DESPITE LOW-LEVEL JET OVER AREA AND SFC TEMPS
WARMING TO NEAR 80 DEGREES...INSTABILITY NOT FORECAST TO BE THAT
HIGH WITH DUE TO THE WARMING/CAPPING ALOFT AS MLCAPES ARE FORECAST TO
BE LESS THAN 1000J/KG AND EDGE OF GREATER CAPE GRADIENT STAYS TO THE
SOUTHWEST OF CWA DURING PEAK HEATING THU AFTN. CANNOT RULE OUT TSRA
THOUGH DUE TO INCREASE IN LOW-LEVEL THETA-E ADVECTION BUT THINK THE
BIGGER HAZARD COULD BE GUSTY WINDS BROUGHT DOWN BE THE SHRA AS STRONG
WINDS ALOFT ARE TRANSPORTED TO SFC. DCAPES UP TO 1000J/KG DURING THE
AFTN AND 1000-850MB LAPSE RATES OVER 8C/KM SUPPORT THAT IDEA.
COVERAGE AND INTENISTY OF TSRA WILL DEPEND ON HOW MUCH INSOLATION
OCCURS THROUGH DAY AS STRONGEST LARGE SCALE LIFT STAYS TO WEST OF UPR
MICHIGAN DURING THE AFTN.

FINALLY...GIVEN THE STRONG AND GUSTY WINDS AND WARM TEMPERATURES
OVER 20F ABOVE NORMAL IN SOME AREAS...FIRE WX MAY COULD BECOME A
CONCERN WITH RECENT DRYING IN WAKE OF SHRA/TSRA THAT OCCURRED ON
SUNDAY. LACK OF IMPACT FM THAT RAIN SHOWS UP WHEN SEEING JUST HOW
LOW RH VALUES WERE TODAY. MIN RH VALUES ON THU AFTN SHOULD BE MUCH
HIGHER THAN TODAY...BUT STILL ARE EXPECTED TO BE 25-30 PCT OVER
CNTRL UPR MICHIGAN AWAY FM MOISTENING OFF LK MICHIGAN. RH VALUES OF
30-40 PCT ARE EXPECTED ELSEWHERE OVER THE WEST HALF OF UPR MICHIGAN.

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 439 PM EDT WED MAY 6 2015

AS THE PROMINENT RIDGE FROM THE OHIO VALLEY TO NW ONTARIO SHIFTS
EAST...SW MID/UPPER LEVEL FLOW WILL DEVELOP FROM THE SRN PLAINS INTO
THE WRN GREAT LAKES. WARM CONDITIONS THU INTO FRI AHEAD OF AN
ADVANCING FRONTAL BOUNDARY WILL GIVE WAY TO MUCH COOLER WEATHER IN
ITS WAKE FROM THE WEEKEND INTO EARLY NEXT WEEK.

THURSDAY NIGHT...THE MID-LEVEL RIDGE WILL CONTINUE TO SHIFT EAST AS
ANOTHER IN A SERIES OF SHORTWAVES MOVES UP ITS BACKSIDE. THIS IN
TURN WILL PUSH THE SFC TROUGH/FRONTAL BOUNDARY EAST INTO WRN UPPER
MI BY 12Z FRI. THE COMBINATION OF INCREASING MOISTURE...INSTABILITY
AND LIFT ALONG THE FRONTAL BOUNDARY WILL PROVIDE THE FOCUS FOR
SCT/ISOLD SHRA/TSRA INTO UPPER MI. THE GREATEST COVERAGE/CHANCES ARE
EXPECTED TO REMAIN OVER THE WEST...CLOSER TO THE STRONGER MID LEVEL
SUPPORT AND INSTABILITY.

FRI...A SURFACE LOW LIFTING ENE ACROSS JAMES BAY WILL CONTINUE TO
PUSH THE COLD FRONT EAST ACROSS MUCH OF UPPER MI. EXPECT HIGHER
SHRA/TSRA CHANCES OVER THE EAST OF THE CWA...ESPECIALLY DURING THE
AFTERNOON WHEN THE FRONT MOVES INTO THE AREA DURING PEAK HEATING.
HIGHS WILL RANGE FROM THE UPPER 60S ALONG LAKE SUPERIOR AND FAR EAST
TO THE LOWER 80S SCNTRL IN A SW TO W FLOW.

FRI NIGHT INTO SAT...THE 12Z MODELS PARTICULARLY THE ECMWF/GEM
CONTINUE TO SHOW A SHORTWAVE/WEAK SFC WAVE TO RIDE ALONG THE FRONT
AND MAY HELP GENERATE ANOTHER ROUND OF SHRA/TSRA OVER THE SE HALF OF
UPPER MI FRI NIGHT THROUGH SATURDAY MORNING. THE 12Z GFS IS
BASICALLY DRY AS IT BLOWS THE FRONT SE OF THE FCST AREA BY 00Z SAT.
SINCE THE GEM AND PARTICULARLY THE ECMWF CONTINUE TO SHOW A SLOWER
PROGRESSION WITH THE FRONT WL CONTINUE TO KEEP AT LEAST LOW CHC POPS
IN FOR THE SE HALF OF THE FCST AREA.

SAT NIGHT INTO SUNDAY...MODEL CONSENSUS POINTS TOWARD MOSTLY DRY AND
COOLER CONDITIONS FOR THE LATTER HALF OF THE WEEKEND AS A NE FLOW
DEVELOPS AHEAD OF BUILDING SFC HIGH PRES OVER SCNTRL CANADA.

SUN NIGHT-TUE...AS THE SW CONUS CLOSED LOW LIFTS THROUGH THE
PLAINS...MODEL CONSENSUS INDICATES A LARGE AREA OF PCPN WILL SPREAD
NORTH TOWARD THE WRN LAKES IN RESPONSE TO DEEPENING MOISTURE...
INCREASING DEEP LAYER Q-VECT CONV AND 295-300K ISENTROPIC ASCENT. IN
ADDITION TO THE WET AND UNSETTLED WEATHER...TEMPS SHOULD STAY COOLER
AS WELL UNDER A PERSISTENT NE FLOW AS THE SFC LOW ASSOC WITH THE
SYSTEM IS FCST TO TRACK SOUTH AND EAST OF UPPER MI.

TUE NIGHT INTO WED...MODELS SUGGEST A RETURN TO DRIER WEATHER AS THE
MID-LVL TROF MOVES EAST OF THE AREA AND A HIGH PRES RIDGE BUILDS IN
FROM THE WEST. TEMPS SHOULD REMAIN COOL IN A LIGHT NORTHERLY FLOW
WITH HIGHS RANGING FROM THE UPPER 40S NEAR LAKE SUPERIOR TO LOWER
60S ALONG THE WI BORDER. LOWS TUE NIGHT COULD DROP TOWARD THE
FREEZING MARK AT OUR TYPICAL INLAND COLD SPOTS.
&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 719 PM EDT WED MAY 6 2015

VFR CONDITIONS EXPECTED THROUGH THE PERIOD AT ALL SITES. LOW-LEVEL
WIND SHEAR WILL DEVELOP LATER TONIGHT AT KCMX AND KSAW AS LOW-LEVEL
JET MOVES OVER THE REGION. DEEPER MIXING BY THURSDAY AFTN SHOULD
RESULT IN GUSTY SOUTH WINDS MAKING IT TO THE SFC. COULD SEE GUSTS
NEAR 30 KTS.
&&

.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 349 PM EDT WED MAY 6 2015

BROAD LOW PRESSURE DEVELOPING OVER THE PLAINS WILL BRING SOUTH TO
SOUTHEAST WINDS OF LESS THAN 20 KNOTS THROUGH THURSDAY NIGHT. GUSTS
TO 25 KNOTS WILL BE POSSIBLE OVER FAR WESTERN LK SUPERIOR TONIGHT
INTO THURSDAY MORNING...THEN ON THURSDAY FOR THE HIGHER PLATFORMS.
RAIN WITH THE SYSTEM FALLING OVER LK SUPERIOR WILL ALSO ALLOW FOR
AREAS OF FOG AWAY FROM THE UPPER MI MAINLAND. COLD FRONT ASSOCIATED
WITH THE LOW WILL CROSS LAKE SUPERIOR ON FRIDAY...BRINGING NW WINDS
TO 20 KNOTS FRIDAY NIGHT INTO SATURDAY. AS HIGH PRESSURE SETTLES
OVER NORTHERN ONTARIO SATURDAY THROUGH TUESDAY AND LOW PRESSURE
SLIDES FM THE CENTRAL PLAINS TO THE UPPER LAKES...NORTH TO NORTHEAST
WINDS UP TO 25 KTS WILL BE POSSIBLE OVER LAKE SUPERIOR.
&&

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

$$

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


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