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

.UPDATE...
ISSUED AT 1116 AM EDT THU AUG 21 2014

GENERALLY MINOR CHANGES TO GOING FORECAST THIS MORNING...PRIMARILY TO
INCREASE CLOUD COVER GIVEN LATE MORNING VISIBLE IMAGERY SUGGESTING
VERY FEW BREAKS IN THE GOING OVERCAST...WITH TEMPERATURES NEEDING TO
BE TWEAKED DOWN AS A RESULT. CONVECTION ASSOCIATED WITH UPSTREAM
SHORTWAVE CONTINUES TO WANE GIVEN LACK OF DOWNSTREAM INSTABILITY TO
WORK WITH LITTLE LLJ FORCING NORTH OF SURFACE WARM FRONT DRAPED FROM
NORTH IOWA THROUGH SOUTHERN WISCONSIN. THEREFORE...HAVE SLOWED DOWN
INCREASE IN AFTERNOON POPS WITH THE MAJORITY OF ANY CONVECTION VERY
LIKELY TO HOLD OFF UNTIL THIS EVENING.  

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 410 AM EDT THU AUG 21 2014

AT THE PRESENT...THE CWA SITS BETWEEN A WEAK 500MB LOW JUST E OF THE 
U.P. AND A 500MB RIDGE AXIS JUST W OF LAKE SUPERIOR. AT THE 
SFC...THERE IS A 1002MB LOW OVER ERN SD...WITH A SFC WARM FRONT 
EXTENDING ACROSS SRN MN AND SRN WI. THE 850MB PORTION OF THE WARM 
FRONT /BASED ON MODEL ANALYSIS AND SATELLITE DATA/ LOOKS TO BE FROM 
NWRN MN TO NCENTRAL WI TO SRN LOWER MI. FOG AND LOW CLOUDS COVER 
MUCH OF THE CWA /INCLUDING A MARINE DENSE FOG ADVISORY FOR CENTRAL 
AND ERN LAKE SUPERIOR INTO THIS MORNING/. EXPECT THE FOG TO 
DISSIPATE OVER LAND THIS MORNING WITH DAYTIME HEATING. OVER LAKE 
SUPERIOR...EXPECT FOG TO THIN SOME THIS MORNING...BUT WILL CONTINUE 
THROUGH THE SHORT TERM PERIOD.

A GENEROUS CLUSTER OF CONVECTION HAS DEVELOPED ALONG THE WARM FRONT 
OVER THE SWRN QUARTER OF MN AND INTO SRN WI/NRN IL. THESE 
THUNDERSTORMS ARE DECAYING AS THEY MOVE N OF THE WARM FRONT SINCE 
MLCAPES ARE MINIMAL N OF THE FRONT. THE FORECAST FOR TODAY AND 
TONIGHT IS FAIRLY DIFFICULT GIVEN THE AMOUNT OF CONVECTIVELY INDUCED 
UNCERTAINTY THERE IS. WHAT CAN BE SAID IS THAT WHILE THE SFC WARM 
FRONT WILL STAY WELL S OF THE CWA...THE 850MB PORTION OF THE WARM 
FRONT WILL MOVE NE TODAY...APPROACHING IRONWOOD AROUND 18Z AND 
MOVING PAST THE SW THIRD TO HALF OF THE CWA BY 00Z FRI BEFORE 
STALLING OUT/WASHING OUT IN A N-S ORIENTATION OVER THE CENTRAL CWA 
SHORTLY THEREAFTER. MODELS ARE IN GOOD GENERAL AGREEMENT THAT 
MLCAPES INCREASE TO 350-900J/KG OVER THE WRN U.P. AND ALONG THE WI 
BORDER LATE THIS AFTERNOON INTO THIS EVENING ALONG AND BEHIND THE 
850MB WARM FRONT. SEVERE WEATHER IS NOT EXPECTED GIVEN THE MARGINAL 
INSTABILITY AND 0-6KM BULK SHEAR AROUND 30KTS...BUT SOME STRONGER 
STORMS ARE POSSIBLE OVER FAR WRN UPPER MI. ALSO...MODELS AGREE THAT AN 
UPPER JET WILL NOSE INTO THE AREA THIS EVENING...PROVIDING 
ADDITIONAL FORCING FOR ASCENT. MODELS BASICALLY SPLIT INTO TWO CAMPS 
ON PRECIPITATION...THE HIGHER RES MODELS (NAM/REG GEM) SHOW A LOT OF 
CONVECTION WELL S OF THE CWA WHILE ONLY MINIMAL QPF IS SHOWN OVER 
FARTHER N. THIS SCENARIO HAPPENS MORE OFTEN THAN NOT...BUT WITH THE 
850MB WARM FRONT MOVING IN...SUFFICIENT INSTABILITY FOR 
CONVECTION...UPPER JET FORCING OVER THE AREA AND LARGER SCALE MODELS 
KEEPING PRECIP N DID NOT WANT TO GO TOO LOW WITH POPS. OVERALL...DID 
NOT MAKE ANY HUGE CHANGES TO THE PREVIOUS FORECAST GIVEN THE 
UNCERTAINTY WITH THE CONVECTION AND LACKING SUFFICIENT REASONING TO 
MAKE SIGNIFICANT CHANGES. THINK BEST CHANCES FOR PRECIP WILL BE OVER 
THE WRN U.P. AND ALONG THE WI BORDER.

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 345 AM EDT THU AUG 21 2014

NAM SHOWS A 500 MB RIDGE OVER THE GULF COAST WITH A CLOSED 500 MB 
LOW OVER THE DESERT SW AND A TROUGH IN THE WESTERN U.S. 12Z FRI. THE 
RIDGE BUILDS INTO THE UPPER GREAT LAKES 12Z SAT WITH A SHORTWAVE 
EJECTED OUT OF THE DESERT SW INTO THE NORTHERN PLAINS. THE TROUGH IN 
THE WESTERN U.S. MOVES INTO THE NORTHERN ROCKIES AND NORTHERN PLAINS 
12Z SUN. 

DIFFICULT FORECAST COMING UP AS THERE IS REALLY NOTHING TO PIN DOWN 
ON HERE AS THINGS ARE VERY SUBTLE. BIG BUST POTENTIAL FOR 
TEMPERATURES EXIST DEPENDING ON HOW MUCH OR HOW LITTLE CLOUD COVER 
THERE IS AND THIS ALL HINGES ON HOW MUCH OR HOW LITTLE CONVECTION 
OCCURS. I WENT MORE TOWARDS A DRIER SOLUTION WITH MORE SUNSHINE AND 
WENT MORE WITH SLIGHT CHANCE POPS FOR ALMOST EVERY PERIOD AND WARMER 
AND HUMID CONDITIONS FOR THIS FORECAST PERIOD. THINKING IS MAJORITY 
OF CONVECTION WILL STAY TO THE SOUTH AND WEST OF AREA WITH LEFTOVER 
STUFF COMING THROUGH AND THERE COULD BE SOME LAKE BREEZE CONVECTION 
IN THE AFTERNOON AND EARLY EVENING AS WELL WHICH WOULD JUSTIFY AT 
LEAST SLIGHT CHANCE POPS IN FOR MOST AREAS. 

IN THE EXTENDED...ECMWF AND GFS SHOW A 500 MB RIDGE OVER THE UPPER 
GREAT LAKES 12Z SUN WITH A TROUGH ACROSS THE WESTERN HALF OF THE 
U.S. THE RIDGE GETS PUSHED FURTHER TO THE EAST BY THE TROUGH 12Z MON 
WITH A SFC FRONT MOVING THROUGH THE U.P. BY 12Z TUE...THE RIDGE IS 
PUSHED OVER TO THE ERN U.S. WITH TROUGHING INTO THE UPPER GREAT 
LAKES LAGGING BACK INTO THE ROCKIES. THIS TROUGH REMAINS OVER THE 
UPPER GREAT LAKES INTO WED. ABOVE NORMAL TEMPERATURES WILL SLOWLY 
COOL BACK TOWARDS NORMAL BY THE END OF THIS FORECAST PERIOD AND IT 

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 131 PM EDT THU AUG 21 2014

SUMMARY: ANOTHER NIGHT OF POOR FLYING CONDITIONS IS EXPECTED AS A 
WEAK AREA OF LOW PRESSURE MOVES JUST SOUTH OF THE REGION...BRINGING 
THE POTENTIAL FOR A FEW SHOWERS/STORMS THIS EVENING.  

RESTRICTIONS: IMPROVING CONDITIONS ONGOING AS OF THIS WRITING AS 
DAYTIME HEATING IS SLOWLY MIXING OUT EARLIER FOG/LOW STRATUS.  WHILE 
THIS TREND WILL CONTINUE FOR A FEW MORE HOURS /WITH A PERIOD OF VFR 
CONDITIONS EXPECTED...DETERIORATION TO IFR/LIFR CONDITIONS AGAIN 
APPEARS LIKELY IN SOUPY LLEVEL AIRMASS.  BEST CHANCES FOR VLIFR WILL 
AGAIN BE AT CMX...WITH OVERALL SETUP PRETTY SIMILAR TO 24 HOURS 
AGO.  IMPROVEMENT WILL AGAIN OCCUR SLOWLY FRIDAY MORNING...WITH 
MVFR/VFR LIKELY BY LATE MORNING/EARLY AFTERNOON. 

WINDS: SOUTHEAST WINDS AROUND 5KTS THROUGH THE COMING TAF PERIOD.  

THUNDERSTORMS: AS A WARM FRONT APPROACHES THE REGION THIS EVENING 
ISOLATED TO SCATTERED THUNDERSTORMS ARE POSSIBLE AT IWD...MOST 
LIKELY IN THE 00-04Z TIMEFRAME.  THIS ACTIVITY WILL HAVE TROUBLE 
MAKING IT FARTHER EAST AND WHILE A SHRA MAY REACH CMX/SAW...THUNDER 
IS NOT EXPECTED HERE.  

LLWS: NO THREATS THIS CYCLE. 

&&

.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 410 AM EDT THU AUG 21 2014

OVERALL...RELATIVELY WEAK PRESSURE GRADIENTS WILL KEEP WINDS BELOW
20 KNOTS THROUGH THIS WEEKEND. THE STRONGEST WINDS WILL OCCUR OVER 
THE WESTERN THIRD OF LAKE SUPERIOR ON TODAY AND THIS EVENING WHEN 
NORTHEAST WINDS WILL FOCUS ALONG THE WESTERN SHORELINE. IN 
ADDITION...PATCHY TO AREAS OF FOG WILL OCCUR OVER PORTIONS OF LAKE 
SUPERIOR THROUGH THE UPCOMING WEEKEND. THE DENSE FOG ADVISORY FOR 
CENTRAL AND EASTERN LAKE SUPERIOR WAS EXTENDED INTO THIS MORNING AS 
SHIP OBS CONTINUE TO SHOW DENSE FOG. THIS MAY NEED TO BE EXTENDED 
FURTHER DEPENDING ON THE EVOLUTION AND OBSERVATIONS THIS MORNING. 
ADDITIONAL MOISTURE WILL SURGE NORTH THIS AFTERNOON AND REMAIN 
THROUGH SUNDAY...PRODUCING ADDITIONAL OPPORTUNITIES FOR FOG OVER 


&&

.MQT WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LS...NONE.
LM...NONE.
&&

$$

UPDATE...ARNOTT/APX
SHORT TERM...TITUS
LONG TERM...07
AVIATION...ARNOTT/APX
MARINE...TITUS

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