Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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000 FXUS63 KGRR 311923 AFDGRR AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 323 PM EDT THU JUL 31 2014 LATEST UPDATE... SYNOPSIS/SHORT TERM/LONG TERM/HYDRO/MARINE .SYNOPSIS... ISSUED AT 258 PM EDT THU JUL 31 2014 THE UPPER LOW THAT HAS BEEN CENTERED OVER ONTARIO THE PAST COUPLE OF DAYS WILL SHIFT EAST. THIS WILL ALLOW FOR A MODERATING TREND TO THE TEMPERATURES FOR THE END OF THE WEEK HERE IN MICHIGAN. A FEW MAINLY AFTERNOON THUNDERSTORMS COULD DEVELOP FRIDAY AND SATURDAY...OTHERWISE THE WEATHER WILL BE MAINLY DRY. THE MORE SEASONABLE TEMPERATURES WILL PERSIST INTO EARLY NEXT WEEK. && .SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT) ISSUED AT 258 PM EDT THU JUL 31 2014 THE MAIN CHALLENGE IN THE SHORT TERM DEALS WITH THE POTENTIAL FOR SHOWERS AND THUNDERSTORMS EACH DAY. THE STORMS IN WISCONSIN ARE EXPECTED TO DISSIPATE AS THEY TRY TO CROSS LAKE MICHIGAN. SURFACE BASED PARCELS ARE STABLE WITH SHOULD CAUSE THE CONVECTION TO WEAKEN. SATELLITE LOOPS SHOW THE CU ORGANIZING FROM NEAR BIG RAPIDS TO LANSING AND DOWN TO BATTLE CREEK. WE COULD SEE A COUPLE OF SHOWERS DEVELOP IN THIS REGION OVER THE NEXT HOUR OR TWO. GIVEN THE GREATER THAN 1000 J/KG...A THUNDERSTORM CANNOT BE RULED OUT EITHER. THE MOST LIKELY REGION FOR THIS TO HAPPEN WOULD BE EAST OF A BIG RAPIDS TO KALAMAZOO LINE. THE COMBINATION OF LOW LEVEL WARM AIR ADVECTION AND MID LEVEL COOL AIR ADVECTION SUPPORT A HIGHER POTENTIAL FOR THUNDERSTORMS FRIDAY AFTERNOON. BETTER THAN 1000 J/KG SURFACE BASED CAPE DEVELOPS. DEEP LAYER SHEAR WILL BE WEAK. THUS ANY CONVECTION THAT DEVELOPS SHOULD BE PULSE IN NATURE. WILL KEEP THE THUNDER RISK GOING. INSTABILITY DEVELOPS AGAIN ON SATURDAY. WINDS LOOK RATHER LIGHT...SO GOOD SURFACE BASED HEATING EXPECTED. THE LAKE BREEZE COULD BE FOCUSING MECHANISM FOR STORMS SATURDAY AFTERNOON. WILL MAINTAIN THE LOW POP. .LONG TERM...(SUNDAY THROUGH THURSDAY) ISSUED AT 258 PM EDT THU JUL 31 2014 FORECAST CONCERNS CONTINUE TO CENTER AROUND THE MIDDLE OF NEXT WEEK. A WEAK COLD FRONT WILL SLIP SOUTH ACROSS LAKE SUPERIOR MONDAY. A WEAK WAVE OF LOW PRESSURE WILL MAY GENERATE A SHOWER OR STORM MID DAY MONDAY. THE MAIN ISSUE WITH THE FRONT IS THAT IT IS PROGD TO STALL OVER THE MIDDLE OF THE CWA MONDAY AFTERNOON DUE TO A DEEPER DEVELOPING LOW OVER THE NORTHERN PLAINS PUSHING WARMER AIR NORTHWARD ON THE WEST END OF THE FRONT. SEVERAL SHORT WAVES ARE PROGD TO MOVE ALONG THE BOUNDARY IN GENERAL NW FLOW ALOFT AND EACH WAVE WILL BRING A CHANCE OF PCPN. AS THE MAIN LOW MOVES EAST WED-THU...HEAVIER RAIN IS POSSIBLE ACROSS WISCONSIN AND CENTRAL LOWER MI. BOTH THE GFS AND ECMWF HAVE BEEN SHOWING THIS SIGNAL FOR A FEW RUNS NOW. LLJ RAMPS UP ACROSS WISCONSIN LATE WEDNESDAY AHEAD OF THE LOW AND AS A RESULT...SHEAR VALUES INCREASE SUBSTANTIALLY. MAIN OPPORTUNITY FOR SVR WX LOOKS TO BE IN THE WED/THU TIME FRAME. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 137 PM EDT THU JUL 31 2014 VFR WX EXPECTED THIS AFTERNOON. ERN TAF SITES WILL SEE MORE CLOUD COVERAGE THIS AFTERNOON. A SHOWER OR BRIEF TSRA IS ALSO POSSIBLE AND COVERED WITH A VCSH. FOG MAY BE AN ISSUE AT KMKG FRIDAY MORNING DUE TO PROXIMITY NEAR THE LAKE WHERE COLDER LAKE TEMPS WILL CAUSE SFC TEMPS AT KMKG TO COME CLOSER TO DEWPOINT. && .MARINE... ISSUED AT 258 PM EDT THU JUL 31 2014 THE COMBINATION OF WARMING SURFACE TEMPERATURES AND THE ARRIVAL OF WARMER WATER SHOULD SUPPORT A DECREASING TREND TO THE FOG THIS AFTERNOON. MUSKEGON GLERL OBSERVATION SHOWED A RISE IN THE SURFACE TEMPERATURE OF 3 DEGREES FROM ROUGHLY 17Z TO 18Z. CAMS SHOW THE FOG PERSISTING THOUGH. WILL HANG ONTO THE HEADLINE FOR NOW. MUCH LESS IN THE WAY OF FOG IS EXPECTED FOR FRIDAY AS THE WARM WATER ADVECTION ALTERS THE FOG SETUP FOR THE NEARSHORE WATERS. WEAK PRESSURE GRADIENT WILL KEEP THE WINDS UNDER 20 KNOTS...AND THUS WAVE WILL REMAIN LOW THROUGH THE WEEKEND. && .HYDROLOGY... ISSUED AT 258 PM EDT THU JUL 31 2014 BASIN AVERAGE QPF STAYS MINIMAL THROUGH THE END OF THE WEEK. THUS NOT SIGNIFICANT RIVER RISES EXPECTED. ISOLATED STORMS COULD LOCALLY PRODUCE UP TO A HALF INCH OF RAIN. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...DENSE FOG ADVISORY UNTIL 9 PM EDT THIS EVENING FOR LMZ846>848. && $$ SYNOPSIS...MJS SHORT TERM...MJS LONG TERM...93 AVIATION...93 HYDROLOGY...MJS MARINE...MJS

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