Area Forecast Discussion
Issued by NWS Marquette, MI

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342
FXUS63 KMQT 171950
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
350 PM EDT SUN MAY 17 2015

.UPDATE...
ISSUED AT 349 PM EDT SUN MAY 17 2015

OVERALL...FORECAST THOUGHTS HAVE NOT CHANGED TOO MUCH OVER THE LAST
FEW HOURS. THE FIRST WAVE OF SHOWERS WITH ISOLATED THUNDERSTORMS
WILL BE MOVING THROUGH THE AREA ALONG AND BEHIND THE WARM FRONT
LIFTING NORTH THROUGH THE AREA LATE THIS AFTERNOON. THERE HAVE BEEN
LIMITED CLOUD-GROUND AND CLOUD-CLOUD LIGHTNING STRIKES THUS
FAR...LARGELY TIED TO THE WEAK MID LEVEL LAPSE RATES AND IN TURN
MUCAPE VALUES GENERALLY LESS THAN 500 J/KG. WITH LITTLE CHANGE
EXPECTED IN THE INSTABILITY OVER MUCH OF THE CWA...EXPECT THE
SHOWERS TO LIFT IN AND PRODUCE SOME RUMBLES OF THUNDER AND MAYBE
BRIEF GUSTY WINDS AND SMALL HAIL. THE STRONGER STORMS WILL BE
ASSOCIATED WITH THE VORT MAX LIFTING NORTH THROUGH MINNESOTA AT
THIS TIME AND PRODUCING SEVERAL AREAS OF THUNDERSTORMS. WITH
BETTER INSTABILITY THERE DUE TO STEEPENING MID LEVEL LAPSE RATES
BEHIND THE INITIAL SHORTWAVE...THAT CONTINUES TO BE THE BEST
OPPORTUNITY FOR STRONGER THUNDERSTORMS IN THE CWA. BUT WITH THAT
MOVING NORTH-NORTHEAST...ONLY THINK IT WILL BRUSH THE AREA AS
ADDITIONAL INSTABILITY IS LOST WITH DIURNAL COOLING. WITH COVERAGE
EXPECTED TO BE LIMITED...HAVE JUST WENT WITH CHANCE POPS AS THE
SECOND WAVE MOVES THROUGH.

FINALLY FOR FOG. WAS ORIGINALLY PLANNING ON A DENSE FOG ADVISORY
FOR DELTA AND SOUTHERN SCHOOLCRAFT COUNTY...BUT LATEST VISIBLE
SATELLITE IMAGES SHOW THE NORTHERN EDGE OF THE DENSE FOG OVER LAKE
MICHIGAN SHIFTING SOUTH UNDER EAST TO NORTHEAST WINDS. THUS...THINK
THE DENSE FOG WILL BE DELAYED FROM EARLIER THOUGHTS AND MAINLY LATE
EVENING INTO THE FIRST PART OF THE OVERNIGHT HOURS FOR DELTA COUNTY
AND AFTER MIDNIGHT THROUGH AROUND DAYBREAK FOR SOUTHERN
SCHOOLCRAFT. HAVE CONTINUED TO HIT THE FOG HARD IN THE GRIDS FOR
THAT AREA (WIDESPREAD FOG) AND WILL ISSUE A QUICK SPS TO GIVE A
HEADS UP ON DETERIORATING CONDITIONS OVERNIGHT. IF CONDITIONS FALL
AS EXPECTED...THE EVENING SHIFT WILL LIKELY NEED TO ISSUE A DENSE
FOG ADVISORY.
&&

.SHORT TERM...(THIS AFTERNOON THROUGH MONDAY)
ISSUED AT 1223 PM EDT SUN MAY 17 2015

WATER VAPOR IMAGERY SHOWS AN UPPER LOW/TROUGH OVER THE EASTERN
DAKOTAS WHILE A STRONG SHORTWAVE LIFTS NORTH THROUGH MINNESOTA.
SHOWERS AND SOME THUNDERSTORMS HAVE BEEN OCCURRING ON THE NOSE OF
THIS SHORTWAVE IN NORTHERN/CENTRAL MINNESOTA AND WILL CONTINUE TO
LIFT TO THE NORTH. MEANWHILE...A 997MB SURFACE LOW IS LOCATED IN
NORTHEAST SOUTH DAKOTA AND IS SLOWLY LIFTING TO THE
NORTH-NORTHEAST. SEVERAL BOUNDARIES EMANATE FROM THE SURFACE LOW
TO THE SOUTHEAST AND WILL BE THE FOCUS FOR SHOWERS AND THUNDERSTORMS
THIS AFTERNOON/TONIGHT. THE FIRST BOUNDARY THAT WILL INFLUENCING THE
AREA IS A WARM FRONT THAT IS STRETCHING EAST ACROSS CENTRAL
MINNESOTA AND INTO NORTHERN WISCONSIN. NORTH OF THIS BOUNDARY THERE
ARE PLENTY OF LOW CLOUDS AND FOG...AIDED BY THE SOUTH-SOUTHEASTERLY
FLOW OFF LAKE MICHIGAN. AS THE SHORTWAVE CONTINUES NORTH AND STARTS
TO INTERACT WITH THAT FRONT...WOULD EXPECT THE SCATTERED SHOWERS AND
THUNDERSTORMS IN WESTERN WISCONSIN TO CONTINUE TO LIFT NORTH TOWARDS
THE CWA. THAT IDEA IS CONSISTENT WITH HIGH RESOLUTION MODELS AND
WILL FOLLOW THAT IDEA WITH THEM RACING TO THE NORTH AROUND 40-45KTS.
THERE ARE A COUPLE CONCERNS TO THE FORECAST WITH THESE
STORMS...ESPECIALLY WITH THEIR EASTWARD EXTENT AND SEVERE POTENTIAL.
FIRST...WITH THE ABUNDANT CLOUD COVER BOTH OVER WISCONSIN AND UPPER
MICHIGAN...HAVEN/T SEEN MUCH DESTABILIZATION THUS FAR WITH MUCAPE
VALUES RUNNING AROUND 250-500 J/KG IN WISCONSIN. THAT IS EXPECTED
WITH THE VERY MARGINAL MID LEVEL LAPSE RATES SEEN ON BUFKIT
SOUNDINGS AND 12Z KGRB SOUNDINGS. THUS...EXPECT THE BULK OF THE
SUPPORT FOR THE DEVELOPING SHOWERS/THUNDERSTORMS TO BE TIED TO THE
FORCING ALONG THE FRONT AND SHORTWAVE. AS THIS FIRST BATCH OF
SHOWERS/THUNDERSTORMS MOVE IN THE WESTERN U.P. WOULD EXPECT THE POOR
INSTABILITY TO KEEP THE INTENSITY AT BAY. IN ADDITION...WITH THESE
STORMS LIKELY BEING ELEVATED...THE 0-6KM BULK SHEAR VALUES OF
40-50KTS WON/T BE AS USEFUL AND LOOKING AT THE EFFECTIVE SHEAR
VALUES...THEY ONLY AMOUNT TO 15-25KTS OF SHEAR WHEN THESE INITIAL
STORMS MOVE THROUGH (GREATEST OVER THE FAR WEST TOWARDS IRONWOOD).
THUS...THINK THE SEVERE THREAT WILL BE LARGELY CONFINED TO THE FAR
WEST INITIALLY...ALTHOUGH WILL LIKELY BE PRETTY LIMITED AND MAINLY
SMALL HAIL AND BRIEFLY GUSTY WINDS. WITH THIS EARLY ISSUANCE OF THE
AFD...WILL ISSUE AN UPDATE IN THE AFTERNOON WITH THE LATEST
THOUGHTS.

HEADING INTO THIS EVENING...THE SURFACE LOW WILL SHIFT NORTHEAST
FROM FARGO AND TOWARDS THE MINNESOTA ARROWHEAD. AS THIS OCCURS...IT
WILL LIFT ANOTHER WARM FRONT NORTHEAST ACROSS UPPER
MICHIGAN...WHILE THE EASTERN EDGE OF THE MAIN SHORTWAVE WILL LIFT
NORTH ACROSS WESTERN UPPER MICHIGAN. THIS WILL PROVIDE AMPLE SUPPORT
FOR A SECONDARY ROUND OF THUNDERSTORMS TO DEVELOP IN NORTHWEST
WISCONSIN AND LIFT INTO THE WESTERN U.P.. WITH DRYING ALOFT AND
STEEPENING LAPSE RATES ASSOCIATED WITH THE SHORTWAVE...THINK THIS IS
THE BETTER OPPORTUNITY FOR SEVERE WEATHER IN THE CWA (LIKELY
OCCURRING AROUND OR AFTER 00Z). ONCE AGAIN...WITH THE BETTER FORCING
FOCUSED OVER THE WESTERN HALF OF THE CWA AND THE EXPECTED
NORTH-NORTHEAST MOVEMENT OF THE STORMS...THINK AREAS SOUTHWEST OF A
LINE FROM HOUGHTON TO IRON MOUNTAIN WOULD HAVE THE BEST SEVERE
THREAT. ASSUMING SOME CLEARING OCCURS OVER THE WEST LATE THIS
EVENING...COULD SEE ML CAPE VALUES NEARING 500 J/KG OR EVEN A LITTLE
HIGHER IN THAT AREA. THAT COMBINED WITH THE STRONGER FORCING AND
EFFECTIVE BULK SHEAR VALUES RISING TOWARDS 40KTS...THINK THERE IS
SOME CONCERN FOR SEVERE STORMS THIS EVENING OVER THE WEST. WILL NEED
TO WATCH IF ANY OF THESE STORMS BECOME ROOTED TOWARDS THE
SURFACE...AS THE SHEAR PROFILES WOULD THEN BECOME FAVORABLE FOR
ROTATING UPDRAFTS. CONFIDENCE ON THUNDERSTORMS OCCURRING DECREASES
AS YOU HEAD EAST AND AWAY FROM THE BEST FORCING...BUT THERE SHOULD
BE ENOUGH ENERGY FROM THE SHORTWAVE TO LEAD TO SCATTERED TO ISOLATED
SHOWERS AND THUNDERSTORMS.

BEHIND THE WARM FRONT FOR THE REST OF THE NIGHT INTO MONDAY...THE
FOCUS TURNS TO THE ARRIVAL OF THE COLD FRONT OVER THE WEST AND THE
FOG AND LOW CLOUDS OVER THE EAST. THE SURFACE LOW WILL BEGIN TO
WEAKEN AS IT MOVES EAST OVER NORTHERN LAKE SUPERIOR OVERNIGHT
TONIGHT AND WILL CONTINUE QUICKLY TO THE EAST THROUGH THE DAY MONDAY
AS IT MOVES INTO QUEBEC. THIS WILL LEAVE A SURFACE TROUGH BACK OVER
LAKE SUPERIOR AS THE UPPER TROUGH IS OVER NORTHERN MINNESOTA AND
NORTHWEST ONTARIO. WITH LITTLE SOUTHEAST MOVEMENT ON BOTH FEATURES
DURING THE OVERNIGHT INTO MONDAY MORNING TIME PERIOD...EXPECT UPPER
MICHIGAN TO BE UNDER THE DRY SLOT ALOFT AND LITTLE PRECIPITATION
EXPECTED. WITH WARM/MOIST AIR NEAR THE SURFACE...EXPECT THE
POTENTIAL FOR FOG TO CONTINUE INTO THE EVENING OVER THE CENTRAL
BEFORE WINDS BEGIN TO BACK TO THE SOUTHWEST BEHIND THE FRONT.
FARTHER EAST...EXPECT THE STRONG INVERSION THAT DEVELOPS AROUND
950-925MB WITH THE WARM FRONT TO LIMIT MIXING OF THE LOW LEVEL AIR
WITH THE FAVORABLE LONG FETCH FLOW OFF LAKE MICHIGAN. WITH THE
EAST-SOUTHEASTERLY FLOW SEEN THUS FAR THIS MORNING ACROSS LAKE
MICHIGAN (LOW 60S DEWPOINTS OVER LOWER MICHIGAN MOVING ACROSS THE 36
DEGREE WATER TEMPS AT THE 45002 LAKE MICHIGAN BUOY)...VISIBILITIES
ALONG THE IMMEDIATE SHORELINE OF LAKE MICHIGAN HAVE BEEN AROUND
1/4-1MI. WITH LITTLE CHANGE TONIGHT AND SLOWLY BACKING FLOW
TO THE SOUTH AND THEN SOUTHWEST TOMORROW MORNING...EXPECT THE FOG TO
SPREAD INLAND THROUGH THE NIGHT AND LIKELY BE DENSE AT TIMES INTO
TOMORROW MORNING. DEFINITELY CONSIDERING A DENSE FOG ADVISORY FOR
THE EASTERN COUNTIES FOR THE AFTERNOON FORECAST PACKAGE.

FOR THE REST OF MONDAY...THE COLD SURGE WILL BEGIN DURING THE
MID-LATE MORNING TIME PERIOD OVER THE WEST AND CONTINUE EASTWARD
THROUGH THE DAY. AHEAD OF THE FRONT (CENTRAL U.P.) AND WHERE THE
COLD LAKE MICHIGAN WATER TEMPS AREN/T INFLUENCING
CONDITIONS...SHOULD SEE TEMPERATURES IN THE MID TO UPPER 60S (WITH A
FEW 70S POSSIBLE IF THERE ARE BREAKS IN THE LOW CLOUDS). THERE IS A
HIGH BUST POTENTIAL WITH TEMPS TOMORROW OVER THE CENTRAL U.P. AS
A LITTLE VARIATION IN THE LOCATION OF THE COLDER AIR OVER THE WEST
AND THE FOG OVER THE EAST WILL MAKE A HUGE DIFFERENCE FOR HIGHS. IN
ADDITION...ALL OF THE HIGHER RESOLUTION MODELS ARE SURGING IN A
LAKE BREEZE OFF LAKE SUPERIOR (FROM MARQUETTE EASTWARD) AND LEADING
TO COOL NORTHERLY FLOW BY MID-LATE AFTERNOON. MEANWHILE...OVER THE
FAR WEST...TEMPERATURES WILL STRUGGLE TO RISE MUCH ABOVE EARLY
MORNING TEMPERATURES IN THE UPPER 40S TO LOWER 50S AND WILL KEEP
THAT IDEA OF STEADY TEMPS OVER THE WEST AND THEN FALLING IN THE
AFTERNOON OVER THE CENTRAL. WITH THE COLD AIR AND ABUNDANT MOISTURE
SURGING INTO THE AREA AS WINDS TURN WESTERLY...WILL SHOW ISOLATED TO
SCATTERED SHOWERS DEVELOPING OVER THE WEST FIRST (ESPECIALLY IN THE
FAVORED UPSLOPE AREAS) AND THEN SPREADING INTO THE CENTRAL AND MAYBE
EVEN EAST BY EVENING.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 407 AM EDT SUN MAY 17 2015

AS HAS BEEN TALKED ABOUT FOR SEVERAL DAYS...SPLIT FLOW WILL PERSIST
ACROSS THE CONTINENT FOR THE FORESEEABLE FUTURE...WITH STRONG
POSITIVE HEIGHT ANOMALIES ACROSS NW CANADA. THIS SHOULD KEEP THE
UPPER GREAT LAKES IN STRONGLY CONFLUENT FLOW FOR MUCH OF THE
FORECAST PERIOD BEYOND TUESDAY...YIELDING A DRY FORECAST INTO
MEMORIAL DAY WEEKEND.

AS FOR MONDAY...THE NWP ARE IN GOOD AGREEMENT IN SHOWING THE
OCCLUDED FRONT MOVING ACROSS THE AREA DURING THE MORNING HOURS. WITH
THE AREA BEING IN THE DRY SLOT IN THE MORNING AND STRONG
MID LEVEL Q-VECTOR DIVERGENCE...EXPECT ANY PRECIPITATION TO BE
CONFINED TO NEAR LAKE MICHIGAN WHERE MOIST ONSHORE FLOW WILL KEEP
CHANCES OF DRIZZLE/FOG IN THE MORNING HOURS BEFORE THE WINDS TURN
WESTERLY. BEHIND THE FRONT...COMMA HEAD MOISTURE WILL ATTEMPT TO
WRAP INTO THE AREA...BUT THE DEEPER MOISTURE WILL REMAIN OVER FAR
WESTERN LAKE SUPERIOR INTO MINNESOTA UNTIL LATE IN THE DAY INTO THE
OVERNIGHT HOURS. COULD BE A PASSING SHOWER MONDAY AFTERNOON ACROSS
THE WEST AND KEWEENAW AS THE DEEPER MOISTURE WRAPS IN BEHIND THE
FILLING AREA OF LOW PRESSURE AND INCREASING UPSLOPE FLOW DUE TO NW
WINDS. STRONG COLD ADVECTION AS THE UPPER TROUGH MOVES EAST OF THE
AREA WILL ALLOW FOR 850MB TEMPS TO DROP TO -9C ACROSS MUCH OF THE
AREA. THIS COMBINED WITH NW FLOW WILL ALLOW FOR ANY RAIN SHOWERS TO
CHANGE TO SNOW AND PERHAPS INCREASE IN AREAL COVERAGE ACROSS THE
WESTERN PART OF UPPER MICHIGAN. DUE TO THE COLD TEMPERATURES AND
PRECIPITATION OCCURING DURING THE OVERNIGHT HOURS...COULD NOT
TOTALLY RULE OUT A DUSTING TO LOCALLY AN INCH OVER GRASSY AREAS
MONDAY NIGHT INTO TUESDAY MORNING BUT GIVEN THE LACK OF SIGNIFICANT
SYNOPTIC SUPPORT DUE TO THE BEST UPPER ENERGY REMAINING WEST AND
NORTH OF THE AREA...DO NOT EXPECT ANY MORE THAN THAT AT THIS TIME.
COLD AND WINDY DAY ON TUESDAY WITH DRYING ACROSS THE ENTIRE AREA
LIKELY CAUSING ANY PRECIPITATION NEAR LAKE SUPERIOR TO SUBSIDE
DURING THE AFTERNOON HOURS.  STILL...IT WILL BE QUITE RAW WITH
TEMPERATURES 15-20 DEGREES BELOW NORMAL.

HEIGHTS BEGIN TO RISE ON WEDNESDAY AS THE UPPER RIDGE OVER THE
WRN ATLC BREAKS DOWN SLIGHTLY...ALLOWING THE LONG WAVE TROUGH OVER
THE REGION TO SHIFT EAST. THIS WILL ALLOW FOR SOME MODEST WARMING AT
850MB TO +4C BY WED EVENING ...WHICH COMBINED WITH THE SUNSHINE
SHOULD ALLOW FOR TEMPS TO GET AT LEAST INTO THE 50S OR LOWER 60S ON
WEDNESDAY....BUT STILL BELOW NORMAL FOR THIS TIME OF YEAR. CONTINUED
WARMING ON THURSDAY AHEAD OF AN UPPER DISTURBANCE ROTATING AROUND
THE UPPER LOW OVER NW QUEBEC. THE GFS AND ECMWF SUGGEST THIS UPPER
DISTURBANCE WILL CLIP THE UPPER GREAT LAKES THU NIGHT...HOWEVER
GIVEN THE VERY DRY AIRMASS IN PLACE ACROSS THE REGION NO
PRECIPITATION IS EXPECTED. WILL GO WITH SLIGHTLY COOLER TEMPS FRIDAY
AS 850MB TEMPS DROP BACK TO -1C. WARMER ON SATURDAY AND STILL DRY AS
HEIGHTS RISE ONCE AGAIN.
&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 158 PM EDT SUN MAY 17 2015

COMPLICATED TAF FORECAST AS SOUTH-SOUTHERLY FLOW OFF LAKE MICHIGAN
HAS LED TO LOW CLOUDS AND FOG AT KSAW THROUGH THE MORNING. EXPECT
THAT TO CONTINUE THROUGH THE EVENING HOURS...AIDED BY THE POTENTIAL
FOR SHOWERS AND MAYBE A THUNDERSTORMS...BEFORE WINDS BEGIN TO SHIFT
TO THE SOUTH-SOUTHWEST OVERNIGHT. THIS SHOULD LEAD TO THE
DIMINISHMENT OF THE FOG AND LOW CLOUDS AT KSAW.

AT KIWD...EXPECT THAT SITE TO HAVE TO BEST CHANCE FOR TWO WAVES OF
SHOWERS AND POSSIBLE THUNDERSTORMS. THE FIRST WAVE WILL ARRIVE
AROUND THE TAF VALID TIME AND CONTINUE FOR A COUPLE HOURS. WITH
MARGINAL INSTABILITY IN THE AREA...HAVE LEFT OUT THUNDER AND WILL
AMEND IF ANY OF THE SHOWERS START TO HAVE LIGHTNING. IN
ADDITION...COULD SEE A VERY BRIEF PERIOD OF MVFR VISIBILITIES...BUT
THOUGHT THE PREVAILING VSBYS WOULD BE VFR. THE NEXT WAVE WILL
ARRIVE LATE THIS AFTERNOON AND INTO THE EVENING...BRINGING A BETTER
CHANCE OF THUNDERSTORMS ALTHOUGH IT WAS TOO FAR OUT TO INCLUDE
THUNDER. AFTER VFR CONDITIONS DURING THE OVERNIGHT HOURS...COLD AIR
ARRIVING BEHIND A COLD FRONT WILL BRING MVFR CEILINGS LATE TONIGHT
INTO MONDAY ALONG WITH A FEW SHOWERS AROUND THE END OF THE TAF
PERIOD.

KCMX WILL BE SIMILAR TO KIWD...ALTHOUGH THE SHOWER/THUNDERSTORM
POTENTIAL WILL BE A LITTLE LOWER. IF SHOWERS OCCUR FAR ENOUGH TO
THE EAST...COULD SEE FOG DEVELOP OVER SOUTH CENTRAL LAKE SUPERIOR.
WITH THE EXPECTED WINDS...THINK IT WILL STAY NORTHEAST OF THE
SITE...BUT WILL BE SOMETHING TO MONITOR. LIKE KIWD...EXPECT MVFR
CEILINGS TO ARRIVE LATE IN THE TAF PERIOD AS WINDS SHIFT TO THE
WEST.
&&

.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 519 AM EDT SUN MAY 17 2015

LOW PRESSURE APPROACHING FROM THE SW WILL ALLOW FOR GRADUALLY
INCREASING E TO SE FLOW TODAY. GUSTS COULD REACH AS HIGH AS 30 KNOTS
FOR THE HIGHER PLATFORMS CENTRAL AND EAST. WARM AND MOIST AIR
SURGING NORTH AHEAD OF THE LOW WILL KEEP FOG IN THE FORECAST THROUGH
AT LEAST MONDAY MORNING BEFORE WINDS TURN NW AND DRIER AIR SCOURS
OUT THE FOG. FOG COULD GET DENSE LATER TONIGHT INTO MONDAY MORNING
OVER THE EAST HALF OF THE LAKE WITH ADDED MOISTENING FROM SHRA
MOVING ACROSS AREA. THE LOW WILL CROSS LAKE SUPERIOR MONDAY AND
MONDAY EVENING. THIS WILL USHER IN NW TO NNW WINDS OF 20 TO 30 KTS
MONDAY NIGHT AND TUESDAY...MAINLY NCNTRL AND EAST HALF. BROAD HIGH
PRESSURE WILL THEN BUILD ACROSS THE REGION WEDNESDAY THROUGH
FRIDAY...BRINGING WINDS DOWN BLO 20 KNOTS.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
  DENSE FOG ADVISORY UNTIL 8 AM EDT MONDAY FOR LMZ221-248-250.

&&

$$

UPDATE...SRF
SHORT TERM...SRF
LONG TERM...MRD
AVIATION...SRF
MARINE...VOSS



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