Area Forecast Discussion
Issued by NWS Marquette, MI

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000
FXUS63 KMQT 220026
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
826 PM EDT THU AUG 21 2014

.UPDATE...
ISSUED AT 825 PM EDT THU AUG 21 2014

REMOVED THUNDER FROM FCST AREA FOR TONIGHT INTO FRIDAY AND ALSO
LOWERED POPS TO MAINLY SLIGHT CHC AS IT LOOKS LIKE BEST CHC FOR
CONVECTION WILL STAY ALONG AND NORTH OF WARM FRONT SITUATED OVER
CENTRAL WI. ALSO RISING 5H HEIGHTS OVER THE AREA SHOULD GENERALLY
SUPPRESS CONVECTION THROUGH PD.
&&

.SYNOPSIS...
ISSUED AT 316 PM EDT THU AUG 21 2014

INCREASING HEAT AND HUMIDITY IS EXPECTED AS WE MOVE INTO THE COMING
WEEKEND AS A RIDGE OF HIGH PRESSURE BUILDS INTO THE GREAT LAKES
REGION. SHOWER AND THUNDERSTORM CHANCES WILL INCREASE BY THE SECOND
HALF OF THE WEEKEND AS LOW PRESSURE AND ITS ASSOCIATED COLD FRONT
BEGINS SLOWLY APPROACHING THE REGION FROM THE WEST.
&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT)
ISSUED AT 316 PM EDT THU AUG 21 2014

...A FEW THUNDERSTORMS THIS EVENING...THEN FOG REDEVELOPS
OVERNIGHT...

HIGH IMPACT WEATHER POTENTIAL: A FEW THUNDERSTORMS POSSIBLE THIS
EVENING FROM MARQUETTE WEST /NO SEVERE THREAT/...WITH PRIMARY HIGH
IMPACT WEATHER THREAT TRANSITIONING TO LAND/MARINE FOG OVERNIGHT.

PATTERN SUMMARY/IMPLICATIONS: RECENT TROUGHING THAT HAS BEEN LOCATED
ACROSS THE GREAT LAKES REGION OVER THE PAST FEW DAYS IS VERY
GRUDGINGLY PUSHING EAST AS WESTERN TROUGH BEGINS TO TAKE SHAPE WITH
DOWNSTREAM RIDGING JUST BEGINNING TO BUILD NORTH FROM THE CENTRAL
PLAINS INTO THE UPPER MISSISSIPPI VALLEY.  SHORTWAVE AT THE LEADING
EDGE OF THIS BUILDING RIDGE IS DAMPENING AS IT RUNS INTO WHAT IS
SOMEWHAT OF A REX BLOCK OVER EASTERN CANADA. MOVING DOWN TO THE
SURFACE A WEAK LOW IS CENTERED OVER THE NORTHERN PLAINS WITH
A WARM FRONT DRAPED FROM SOUTHERN MINNESOTA SOUTH OF THE GREAT
LAKES. PRIMARY CONVECTIVE ACTIVITY IS ALONG THIS FRONT...WITH SOME
REACHING NORTH INTO EASTERN WISCONSIN AHEAD OF THE AFOREMENTIONED
WAVE.

THROUGH EARLY THIS EVENING: UPSTREAM SHORTWAVE CONTINUES TO SHEAR
OUT AS IT PUSHES TOWARDS WESTERN UPPER MICHIGAN THROUGH THIS
EVENING.  RADAR TRENDS HAVE BEEN VERY LACK-LUSTER...NOT SURPRISING
GIVEN CURRENT MUCAPE ANALYSIS WHICH SHOWS MEANINGFUL INSTABILITY
STILL OVER SOUTHERN WISCONSIN.  THE REMNANT "ARC" OF CONVECTION IS
CONTINUING TO PUSH EAST...AND WITH CONTINUED AFTERNOON HEATING...
COULD SEE A FEW SPOTS ALONG THE WISCONSIN/MICHIGAN BORDER SEE A
SHOWER OR THUNDERSTORM HEADING INTO THE EVENING.  STILL AMPLE
CLOUDINESS FOR ALMOST ALL LOCATIONS...WITH TEMPERATURES IN THE
LOW/MID 70S.

TONIGHT: CHALLENGING CONVECTIVE FORECAST THIS EVENING...BUT
CONFIDENCE IS GROWING ON A SCENARIO THAT SHOULD KEEP THE MAJORITY OF
STORMINESS SOUTH OF THE REGION TONIGHT.  GIVEN CURRENT LOCATION OF
BEST INSTABILITY...AND CURRENT VIS IMAGERY WHICH SHOWS CLEARING
MOVING INTO SOUTHERN MINNESOTA AND NORTHWEST IOWA...EXPECT THIS TO
BE THE SPOT FOR CONVECTIVE REDEVELOPMENT LATE THIS AFTERNOON AND
EVENING...WITH THIS CONVECTION MOVING SOUTH AND EAST INTO LOWER
MICHIGAN. FURTHER NORTH...WE WILL STILL HAVE SOME WEAK MID LEVEL
FORCING FOR ASCENT...BUT LITTLE IN THE WAY OF INSTABILITY TO WORK
WITH.  THUS...EXPECT SHRA/TSRA CHANCES TO INCREASE FROM WEST TO
EAST...BUT GUT FEELING IS THAT THESE WILL BE ISOLATED TO SCATTERED
AT BEST...AGAIN WITH THE MAJORITY OF ACTIVITY TO OUR SOUTH.

FOG: A GOOD BET THAT WE/LL SEE A REPEAT OF FOG TONIGHT WITH LIGHT
FLOW REGIME IN PLACE AND LITTLE CHANGE TO THE SOUPY LLEVEL AIRMASS.
DENSE FOG WAS PATCHY THIS MORNING /EXCEPT ON THE KEWEENAW/...BUT
WITH A CONTINUED PUSH OF HIGHER THETAE AIR ALOFT...COULD SEE THIS
BEING A LITTLE MORE WIDESPREAD TONIGHT...PARTICULARLY IF WE CAN
REALIZE A FEW BREAKS IN THE CLOUDS.  WILL CERTAINLY INCLUDE MENTION
IN THE AFTERNOON HWO...BUT WILL AWAIT EVENING CLOUD TRENDS BEFORE
HOISTING ANY SORT OF HEADLINE.

TEMPERATURES: CONTINUED CLOUD COVER AND MOIST LLEVELS WILL PROMOTE A
FAIRLY MILD NIGHT WITH LOWS GENERALLY NEAR 60.

WINDS: LIGHT SOUTHEASTERLY FLOW REGIME CONTINUES NORTH OF THE WAVE
OF LOW PRESSURE.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 316 PM EDT THU AUG 21 2014

...WARM AND HUMID THROUGH EARLY NEXT WEEK AND POTENTIALLY
UNSETTLED...

HIGH IMPACT WEATHER POTENTIAL: THUNDERSTORM CHANCES INCREASE FOR THE
SECOND HALF OF THE WEEKEND...WITH CONTINUED THUNDERSTORM CHANCES FOR
NEXT WEEK.  SEVERE THREAT GENERALLY LOW THROUGH EARLY NEXT WEEK.

PATTERN SUMMARY/FORECAST:  IMPORTANT FEATURE OF NOTE EARLY THIS
AFTERNOON IS STRENGTHENING TROUGHING ACROSS WESTERN NOAM...WITH
ADDITIONAL UPSTREAM ENERGY ALONG THE PACIFIC NORTHWEST COAST POISED
TO DIVE INTO THIS TROUGHING...DEEPENING IT FURTHER WITH SUBSEQUENT
RIDGING FORMING DOWNSTREAM OVER THE GREAT LAKES REGION.  SOME DEGREE
OF THIS RIDGING SHOULD HOLD INTO EARLY NEXT WEEK WITH ADDITIONAL
ENERGY ACROSS THE GULF OF ALASKA KICKING SOME...IF NOT ALL OF THE
TROUGHING ACROSS THE WESTERN CONUS EASTWARD...WITH THIS SERVING TO
FLATTEN THE DOWNSTREAM RIDGE AS THE PATTERN BECOMES INCREASINGLY
PROGRESSIVE BY THE SECOND HALF OF NEXT WEEK.

MODEL AGREEMENT/CONFIDENCE: LARGE SCALE PATTERN IS WELL-AGREED UPON
THROUGH MONDAY WITH DIVERGENCE BEYOND THIS...PARTICULARLY RELATING
TO THE AMOUNT OF THE WESTERN CONUS TROUGH THAT EJECTS EASTWARD...AND
THUS THE TIMING/DEGREE OF MIDWEEK COOLING.  ECMWF IS KNOWN TO HOLD
ON TO WESTERN TROUGHING TOO LONG...AND IT IS SHOWING A SIMILAR TREND
IN THIS FORECAST CYCLE...WITH LARGER RUN TO RUN DISCONTINUITY THAN
THE GFS.  WITH THE OPERATIONAL GFS HAVING GOOD ENSEMBLE SUPPORT FROM
THE NAEFS...WILL LEAN CLOSER TO IT/S EVOLUTION THROUGH THE LONG TERM
FORECAST PERIOD.

MIDDLE RANGE /FRIDAY THROUGH SUNDAY/:

MUCH LIKE THE TONIGHT PERIOD...EXPECT THAT WITH THE PRIMARY SURFACE
FRONTAL ZONE REMAINING SOUTH OF THE GREAT LAKES THROUGH
SATURDAY...THAT CONVECTIVE CHANCES THROUGH AT LEAST THIS PERIOD WILL
REMAIN QUITE LOW.  THE AIRMASS WILL BE WARM AND HUMID...AND
THUS...CANNOT RULE OUT A FEW POP UP THUNDERSTORMS ON FRIDAY...AND
HAVE INCLUDED ISOLATED WORDING HERE...MAINTAINING A DRY FORECAST AT
THIS TIME FOR SATURDAY. BY SUNDAY...WESTERN TROUGHING BEGINS TO
ENCROACH ON THE FORECAST AREA FROM THE WEST...WITH FALLING HEIGHTS
AND CONTINUED WARM/HUMID AIR ARGUING FOR AN UPTICK IN THUNDERSTORM
CHANCES /FOR WESTERN AREAS/.

AS MENTIONED BY THE PREVIOUS FORECASTER...DAYTIME TEMPERATURES ARE
HIGHLY DEPENDENT ON CONVECTIVE EVOLUTION.  850 TEMPERATURES WOULD
SUPPORT HIGHS IN THE MID /OR EVEN UPPER/ 80S...BUT EVEN SCATTERED
CONVECTION AND ASSOCIATED CLOUD COVER WOULD KEEP TEMPERATURES WELL
BELOW THIS. HAVING GONE A LITTLE DRIER THAN PREVIOUSLY WITH TODAY/S
FORECAST...HAVE BOOSTED HIGHS A FEW DEGREES THROUGH THIS PERIOD WITH
FORECAST READINGS NOW ON EITHER SIDE OF 80.

LONG RANGE /MONDAY THROUGH THURSDAY/:

UNSETTLED WITH AN EVENTUAL TRANSITION TO COOLER CONDITIONS DURING
THIS PERIOD.  GIVEN THE MODEL DISCUSSION ABOVE...EXPECT THAT ANY
COLD FRONTAL PASSAGE MAY NOT OCCUR UNTIL THE END OF THIS FORECAST
PERIOD. THUS...WILL CONTINUE WITH ABOVE NORMAL TEMPERATURES THROUGH
MONDAY/TUESDAY...GRADUALLY TRENDING BACK TOWARDS CLIMATOLOGY TOWARDS
THE END OF THE LONG TERM FORECAST PERIOD AS CONFIDENCE IN COOLER
TEMPERATURES BY THE END OF THE WEEK GROWS.  WITH AN EXPECTED
SLOWER COLD FRONTAL ARRIVAL...STORM CHANCES WILL CONTINUE FOR MUCH
OF THIS PERIOD...WHICH WILL LIKELY LEAD TO A FAIRLY UNSETTLED WEEK.
&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 724 PM EDT THU AUG 21 2014

LINGERING LOW-LEVEL MOISTURE IN A LIGHT MAINLY UPSLOPE E-SE WIND FLOW
WILL LEAD ONCE AGAIN TO ANOTHER NIGHT OF FOG AND STRATUS AT THE TAF
SITES. LOOK FOR KIWD AND KSAW TO LOWER TO LIFR LATE THIS
EVENING/OVERNIGHT WITH KCMX LOWERING TO VLIFR AND AIRFIELD MINS.
CONDITIONS WILL SLOWLY IMPROVE ON FRIDAY WITH DIURNAL HEATING. EXPECT
KCMX TO IMPROVE TO IFR/LOW END MVFR BY EARLY FRI AFTERNOON WITH KIWD
AND KSAW IMPROVING TO MVFR BY LATE FRI MORNING/EARLY AFTERNOON. BEST
CONVECTION SHOULD STAY SOUTH OF TAF SITES INTO MAINLY CENTRAL WI
ALONG AND JUST NORTH OF WARM FRONT OVER THAT AREA. THERE COULD BE AN
ISOLD SHRA BUT MAINLY OVER THE WRN TAF SITES WHERE I INCLUDED A
MENTION OF VCSH.
&&

.MARINE...
ISSUED AT 316 PM EDT THU AUG 21 2014

...GENERALLY LIGHT WIND FLOW REGIME...

SUMMARY: GENERALLY LIGHT EASTERLY WIND REGIME ACROSS LAKE SUPERIOR
EARLY THIS AFTERNOON BETWEEN HIGH PRESSURE OVER QUEBEC AND LOWER
PRESSURE OVER THE NORTHERN PLAINS/MISSISSIPPI VALLEY.  THE EASTERLY
FLOW REGIME WILL CONTINUE THROUGH FRIDAY AS THIS LOW PRESSURE MOVES
SOUTH AND EAST TOWARDS SOUTHERN LAKE MICHIGAN. LIGHT WINDS WILL
GRADUALLY BECOME MORE SOUTHERLY THROUGH THIS WEEKEND AS ANOTHER AREA OF
LOW PRESSURE TAKES SHAPE OVER THE NORTHERN PLAINS WHILE HIGH PRESSURE
STRENGTHENS OVER THE NORTHEAST AND MID ATLANTIC STATES.

HEADLINES: GENERALLY SUB-ADVISORY CRITERIA THROUGH THIS COMING
WEEKEND GIVEN THIS LIGHT FLOW REGIME. THE GREATEST THREAT FOR
ADVISORY LEVEL WIND GUSTS WILL BE THIS EVENING FROM THE KEWEENAW
WEST UNDER NORTHEAST FLOW WHERE A FEW 20-25KT GUSTS ARE
POSSIBLE...BUT STILL DO NOT EXPECT TO NEED HEADLINES.

FOG: WILL BE MONITORING FOG TRENDS...BUT FOG LOOKS TO REMAIN LIKELY
/ESPECIALLY AT NIGHT/ THROUGH THE WEEKEND AND POTENTIALLY THROUGH THE
FIRST HALF OF NEXT WEEK.
&&

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

$$

UPDATE...VOSS
SYNOPSIS...ARNOTT/APX
SHORT TERM...ARNOTT/APX
LONG TERM...ARNOTT/APX
AVIATION...VOSS
MARINE...ARNOTT/APX





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