Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 020846
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
446 AM EDT WED SEP 2 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 445 AM EDT WED SEP 2 2015

TWO FOCUSES FOR THE SHORT TERM TODAY...THE FOG TO START THE DAY AND
THEN THE POTENTIAL FOR SHOWERS/THUNDERSTORMS OVER THE SOUTHWEST HALF
OF THE CWA. A WARM AND MOIST AIR MASS REMAINS IN PLACE EARLY THIS
MORNING...ESPECIALLY FOR EARLY SEPTEMBER STANDARDS...WITH 4AM
TEMPERATURES IN THE LOW-MID 60S AND DEWPOINTS NEARLY IDENTICAL. THIS
HAS LED TO FOG DEVELOPING THROUGH THE EVENING AND EARLY OVERNIGHT
HOURS...WITH VISIBILITIES RANGING FROM 1/4MI TO 4MI. LOOKING AT
WEBCAMS...THE AREAS OF DENSE FOG SEEM TO BE VERY PATCHY AND THAT
MATCHES THE WAY SOME OF THE OBS HAVE BEEN BOUNCING UP AND DOWN. WITH
THAT VARIABILITY...WILL NOT BE ISSUING A DENSE FOG ADVISORY FOR
ANYWHERE IN THE U.P. BUT WILL CONTINUE TO MONITOR THROUGH THE
MORNING. THIS FOG WILL CONTINUE THROUGH THE FIRST PART OF THE
MORNING BEFORE BURNING OFF. AM WONDERING IF THE HIGH CLOUDS FROM
UPSTREAM CONVECTION WILL SLOW THE DISSIPATION A BIT WHEN COMPARED TO
THE LAST COUPLE OF DAYS SO DID DELAY IT SLIGHTLY.

THE SECOND ITEM OF FOCUS HAS TO DO WITH THE CONVECTION OCCURRING
UPSTREAM IN SOUTHERN MINNESOTA AND NOW EVEN MAKING IT INTO NORTHWEST
WISCONSIN. THIS CONVECTION REALLY TOOK OFF LATE YESTERDAY EVENING IN
RESPONSE TO A SHORTWAVE LIFTING NORTHEAST OUT OF NEBRASKA AND
SOUTHEASTERN SOUTH DAKOTA...ALONG WITH THE NOSE OF 850MB WARM AIR
ADVECTION. THERE ARE TWO DIFFERENT SHORTWAVES AND THAT CAN BE SEEN
WITH THE COVERAGE OF THE SHOWERS/THUNDERSTORMS...WITH A WEAKER WAVE
FARTHER TO THE NORTHEAST FROM THE MAIN WAVE IN SOUTHERN MINNESOTA
AND NORTHERN IOWA. THE NORTHERN WAVE IS ALSO HELPED BY A WEAK WARM
FRONT THAT IS STRETCHING EAST ACROSS NORTHERN MINNESOTA.
MEANWHILE...THE SOUTHERN WAVE SEEMS TO HAVE TAKEN A MORE EAST-
NORTHEAST TRACK OVER THE LAST COUPLE OF HOURS AND HAVE SEEN THE
TRENDS IN BOTH RADAR AND LIGHTNING FARTHER TO THE SOUTH.

SO THERE ARE TWO QUESTION MARKS FOR TODAY. FIRST...HOW MUCH
DEVELOPMENT WILL OCCUR TO THE NORTH OF THE MAIN SHORTWAVE (MID LEVEL
WAA WEAKENS THROUGH THE DAY) AND TWO...HOW FAR NORTH WITH THE
COMPLEX WITH THE MAIN SHORTWAVE MAKE IT. WITH THE LATEST RADAR
TRENDS...HAVE TRENDED THE POP FORECAST UP ALONG THE WISCONSIN BORDER
FOR THIS MORNING AND INTO THE AFTERNOON AS WEAK MID LEVEL Q-VECTOR
CONVERGENCE IS MOVING INTO THE CWA THIS MORNING AND EARLY AFTERNOON
WITH THE SHORTWAVE. MOISTURE IS A LITTLE MORE QUESTIONABLE DUE TO
THE HIGH PRESSURE RIDGE BUILDING SOUTH FROM A HIGH NEAR HUDSON
BAY...BUT THERE SHOULD BE ENOUGH FOR SOME SHOWERS/THUNDERSTORMS. NOT
COMPLETELY SURE HOW FAR NORTH THINGS WILL GO WITH THE GENERALLY SLOW
NORTH-NORTHEAST MOVEMENT DUE TO THE WEAKENING FLOW ALOFT...BUT HAVE
MUCH OF THE WESTERN U.P. IN CHANCE POP CATEGORY BY LATE MORNING AND
EARLY AFTERNOON. FOR THE SECOND QUESTION...LOOKING AT THE FORCING
AND EXPECTED SHORTWAVE TRACK...WOULD EXPECT MOST OF THE SECOND WAVE
OF PRECIPITATION TO BE LOCATED OVER NORTHERN WISCONSIN...WITH THE
NORTHERN EDGE BRUSHING THE SOUTHWESTERN HALF OF THE CWA. HAVE SEEN
SOME OF THE MODELS SHIFTING THE HEAVY PRECIPITATION MUCH FARTHER
NORTH THAN THAT AND BRING A LARGE AREA OF THUNDERSTORMS EAST-
SOUTHEAST ACROSS THE SOUTHERN HALF OF UPPER MICHIGAN. BUT THOSE
MODELS SEEM TO BE STRUGGLING WITH THE LATEST TRENDS IN THE
CONVECTION IN SOUTHERN MINNESOTA AND NORTHERN IOWA...SO CONFIDENCE
IS LOWER IN THAT OCCURRING. PRECIPITABLE WATER VALUES WILL RISE TO
AROUND 1.5 INCHES OVER THE SOUTHWEST PART OF THE CWA AND WHEN
COMBINED WITH FREEZING LEVELS AROUND 11-12KFT...THINK HEAVY RAIN IS
POSSIBLY WHERE THUNDERSTORMS OCCUR (STORM IN NORTHWEST WISCONSIN HAS
1HR RADAR ESTIMATES EXCEEDING 2 INCHES). DIDN/T PUT TOO HIGH OF QPF
IN THE FORECAST DUE TO THE UNCERTAINTY ON THE NORTHERN EXTENT...SO
WILL PROBABLY BE ADJUSTING THAT THROUGH MUCH OF THE DAY AS THE
CONVECTION SHOWS ITS HAND.

THESE SHOWERS AND THUNDERSTORMS SHOULD GRADUALLY SHIFT TO THE
SOUTHEAST THROUGH THE EVENING AND OVERNIGHT HOURS AND HAVE FOLLOWED
THAT IDEA FOR THE POPS. WITH SOME CLEARING ON THE BACK SIDE AND
WARM/MOIST AIRMASS STILL IN PLACE (ALONG WITH ADDED MOISTURE FROM
RAIN)...WILL INCLUDE PATCHY/AREAS OF FOG IN THE FORECAST. LOWS
TONIGHT WILL REMAIN WARM AND GENERALLY IN THE LOWER 60S.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 351 PM EDT TUE SEP 1 2015

AT 00Z THURSDAY A SHORTWAVE WILL BE SET UP ACROSS UPPER MI AND
WI...RIDING THE N EDGE OF THE LARGER 500MB RIDGE SET UP ACROSS MUCH
OF THE CENTRAL U.S.

AS A RESULT...WILL START OFF WITH SLIGHT CHANCE POPS SLOWLY EXITING
SE WEDNESDAY NIGHT...WITH MAINLY DRY WEATHER THEN FIGURED THURSDAY
THROUGH AT LEAST FRIDAY AS THE 500MB RIDGE BUILDS BACK ACROSS THE
UPPER GREAT LAKES. 80S STILL LOOK ON TRACK FOR TEMPS THROUGH
SATURDAY...IF NOT SUNDAY TOO. THERE WILL BE SLIGHT DIFFERENCES EACH
DAY...BUT MAINLY A BETTER PUSH OF AIR OFF LAKE MI WHERE THEY WILL BE
HELD IN THE 70S.

A LOW EJECTING OUT OF THE PACIFIC NW WILL SWING TO THE S CENTRAL
CANADA AND THE DAKOTAS BY 12Z MONDAY...WITH A BREAKDOWN OF THE UPPER
LEVEL RIDGE OVER THE UPPER GREAT LAKES. BEST CHANCE OF RAIN LOOKS TO
BE LATER SUNDAY NIGHT INTO MONDAY. THE LATEST ECMWF SHOWS ONLY
LIMITED PRECIP REMAINING AS THE SYSTEM MOVES E DURING THE DAY
MONDAY. LOOK FOR TEMPERATURES TO FALL BACK TO NEAR NORMAL FOR HIGHS
MONDAY...AND THEN QUITE A CHANGE FOR TUESDAY WITH HIGHS CURRENTLY
ONLY FCST TO BE IN THE MID TO UPPER 60S.
&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 113 AM EDT WED SEP 2 2015

FOG WILL BE AN ISSUE OVERNIGHT WITH VLIFR CONDITIONS EXPECTED AT ALL
SITES THROUGH SUNRISE. IMPROVEMENT TO VFR WILL OCCUR AROUND MID
MORNING ON WED. KIWD HAS THE BEST CHANCE AT SEEING SOME THUNDER AND
HAVE VCSH AND VCTS TO COVER FOR WED MORNING INTO WED AFTERNOON.
&&

.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 445 AM EDT WED SEP 2 2015

A RIDGE OF HIGH PRESSURE WILL SLOWLY BUILD SOUTH OVER LAKE SUPERIOR
THROUGH TONIGHT AS A HIGH MOVES EAST FROM WESTERN HUDSON BAY TO
NORTHERN QUEBEC. THIS HIGH WILL CONTINUE SOUTHEAST INTO THE NEW
ENGLAND STATES THIS WEEKEND...WHILE KEEPING THE RIDGE OVER THE
GREAT LAKES REGION. THIS RIDGE WILL LEAD TO WINDS STAYING BELOW
20KTS FOR MUCH OF THE FORECAST PERIOD AS WINDS GRADUALLY TURN TO
THE SOUTH AHEAD OF A STATIONARY LOW PRESSURE SYSTEM IN THE NORTHERN
PLAINS. THIS LOW WILL FINALLY LIFT NORTHEAST TOWARDS HUDSON BAY
SUNDAY NIGHT INTO EARLY NEXT WEEK...SHIFTING A COLD FRONT EAST
ACROSS THE UPPER GREAT LAKES ON MONDAY. FINALLY...WITH A WARM/MOIST
AIR MASS OVER THE UPPER GREAT LAKES REGION...THERE IS THE POTENTIAL
FOR PATCHY TO AREAS OF FOG OVER LAKE SUPERIOR (MAINLY OVER THE
NORTHERN AREAS)...BUT NOT EXPECTING WIDESPREAD DENSE FOG AT THIS
TIME.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
  DENSE FOG ADVISORY UNTIL 8 AM EDT THIS MORNING FOR LMZ248-250.

&&

$$

SHORT TERM...SRF
LONG TERM...KF
AVIATION...07
MARINE...SRF



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