Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 021919
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
319 PM 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...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 318 PM EDT WED SEP 2 2015

SPENT MOST TIME HELPING WITH SHORT TERM WARNING OPERATIONS...SO
RELIED HEAVILY ON PREVIOUS FORECAST AND CONSENSUS FOR THE LONG TERM
FORECAST.

OVERALL...EXPECT A SOME LOW END SHOWER AND THUNDERSTORM CHANCES IN
THE REGION FRI AND SAT AS THE UPPER RIDGE SITS OVER THE AREA WITH
SHORTWAVES PUSHING THROUGH THE RIDGE. A LOW PRESSURE SYSTEM WILL
MOVE FROM THE INTER-MOUNTAIN WEST LATE SAT TO HUDSON BAY BY
TUE...BRINGING INCREASED SHOWER AND THUNDERSTORM CHANCES SUN THROUGH
MON AS A COLD FRONT MOVES ACROSS. THE PROLONGED HEAT WILL GIVE WAY
TO COOLER TEMPS EARLY NEXT WEEK WHEN HIGH TEMPS WILL DROP DOWN
CLOSER TO NORMAL IN THE 60S AND 70S. ANOTHER SYSTEM MAY MOVE THROUGH
NEXT WED...POSSIBLY BRINGING PRECIP TO MUCH OF THE AREA...BUT
PREDICTABILITY IS LOW WITH THIS SYSTEM.
&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 747 AM EDT WED SEP 2 2015

SEVERAL FEATURES OF NOTE FOR THE TAFS TODAY...WITH GROUND FOG
OCCURRING OVER MUCH OF UPPER MICHIGAN THIS MORNING...WHILE SHOWERS
AND THUNDERSTORMS LIFT NORTHEAST FROM EASTERN MINNESOTA AND
NORTHWEST WISCONSIN. EXPECT THE FOG TO DIMINISH OVER THE NEXT
COUPLE OF HOURS. THE RAIN HAS ALREADY REACHED KIWD AND EXPECT THE
THUNDERSTORM JUST TO THE SOUTHWEST TO AFFECT THE SITE AND HAVE WENT
WITH PREDOMINATE THUNDER FOR THE FIRST TWO HOURS. THERE IS THE
POTENTIAL FOR DOWNBURST WINDS WITH THE HEAVIEST RAIN AND HAVE SEEN
GUSTS TO 30KTS OCCUR UPSTREAM IN WISCONSIN. OTHERWISE...EXPECT THE
SHOWERS TO CONTINUE NORTHEAST THROUGH THE MORNING AND LIKELY NEAR
OR IMPACT KCMX/KSAW. HAVE WENT WITH VCSH FOR NOW DUE TO INDICATIONS
IN THE MODELS THAT THE SHOWERS WILL RUN INTO DRIER AIR TO THE
NORTHWEST AND WEAKENING FORCING. THESE SHOWERS WILL EVENTUALLY
FOCUS BACK TOWARDS THE WISCONSIN BORDER LATER TODAY BEFORE
DEPARTING THIS EVENING. WITH THE RAIN AND A CONTINUED WARM/MOIST
AIR MASS...SHOULD SEE FOG REDEVELOP AGAIN TONIGHT AT ALL THREE
SITES.
&&

.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...
NONE.
&&

$$

SHORT TERM...SRF
LONG TERM...TITUS
AVIATION...SRF
MARINE...SRF


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