404 FXUS63 KAPX 151805 AFDAPX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 205 PM EDT SAT JUN 15 2013 .SYNOPSIS... ISSUED AT 250 AM EDT SAT JUN 15 2013 CLOUDS WILL INCREASE TODAY AS A SERIES OF UPPER LEVEL DISTURBANCES BRING A CHANCE OF SHOWERS AND THUNDERSTORMS TO NORTHERN MICHIGAN BEGINNING THIS AFTERNOON AND CONTINUING THROUGH THE WEEKEND AND INTO EARLY NEXT WORK WEEK. && .UPDATE... ISSUED AT 158 PM EDT SAT JUN 15 2013 SCATTERED RADAR RETURNS OVER NORTHWEST LOWER...SOME SPITS OF RAIN REPORTED AT PLN/FKS/TVC. THINGS SEEM TO BE EVOLVING AS ANTICIPATED... DRY FORECAST OVER EASTERN UPPER STILL LOOKS FINE AND MAY EVEN SEE SOME PEEKS OF SUN LATER. EXPECT THAT BEST CHANCE FOR RAINFALL WILL ARRIVE DURING THE EVENING HOURS AS SHORT WAVE TROUGH MOVING INTO NORTHWEST IOWA SPINS TOWARD LOWER MICHIGAN. EXPECT ADDITIONAL CONVECTIVE DEVELOPMENT AHEAD OF THIS WAVE OVER THE NEXT SEVERAL HOURS THAT EVENTUALLY GETS PUSHED INTO AT LEAST LOWER MICHIGAN BY THIS EVENING. UPDATE ISSUED AT 1209 PM EDT SAT JUN 15 2013 14Z SURFACE/COMPOSITE ANALYSIS SHOWS 1021MB HIGH CENTERED OVER WEST VIRGINIA RIDGING NORTHWESTWARD ACROSS LAKE HURON/FAR EASTERN LAKE SUPERIOR...COLD/OCCLUDED FRONT RUNS FROM NORTHWEST ONTARIO SOUTHWARD INTO THE UPPER MIDWEST/CENTRAL PLAINS. COUPLE WARM FRONTAL STRUCTURES EAST OF THE FRONT...ONE EMANATES FROM A FRONTAL WAVE NEAR MSP AND EXTENDS INTO WISCONSIN...THE OTHER CUTS ACROSS CENTRAL/ SOUTHEAST IOWA. PAIR OF UPPER LOWS TO THE NORTHWEST AND NORTHEAST OF THE GREAT LAKES...WEAK SHORT WAVE RIDGING IN BETWEEN ACROSS ILLINOIS/WISCONSIN. WATER VAPOR IMAGERY SHOWS ANOTHER SHORT WAVE CROSSING THE CENTRAL PLAINS WITH A SMALL MCS IN TOW...MCV MOVING ACROSS NORTHERN ILLINOIS AND A SMALL SCALE CIRCULATION SHOWING UP ON RADAR CROSSING NORTHERN LAKE MICHIGAN. THIS LATTER FEATURE IS PUSHING AN AREA OF LIGHT RAIN SHOWERS AND SPRINKLES TOWARD FAR NORTHWEST LOWER MICHIGAN AS OF LATE MORNING. FARTHER UPSTREAM SCATTERED SHOWERS/THUNDERSTORMS OCCURRING ACROSS WESTERN/CENTRAL UPPER AND NORTHEAST WISCONSIN WITHIN AREA OF LOW LEVEL WARM ADVECTION AND AHEAD OF AN 850MB TROUGH AXIS. LOW LEVELS ARE DRIER ACROSS NORTHERN MICHIGAN PER 12Z APX SOUNDING...BUT AXIS OF DEEPER MOISTURE EXISTS ACROSS WESTERN UPPER/WISCONSIN WHERE PRECIPITABLE WATER VALUES AROUND 1.25 INCH. PARCELS LIFTED FROM 850MB OFF MPX SOUNDING YIELDS 2130J/KG CAPE. WILL CONTINUE WITH THE IDEA OF SPOTTY SHOWERS/SPRINKLES ACROSS NORTHERN LOWER THIS AFTERNOON WITH PASSAGE OF SMALL VORTICITY CENTER ACROSS THE TIP OF THE MITT COUNTIES...AND ADDITIONAL SCATTERED ACTIVITY OCCURRING BEHIND IT. POSSIBLE THAT EASTERN UPPER STAYS MOSTLY DRY THIS AFTERNOON AND WILL TREND THE FORECAST IN THIS DIRECTION. UPDATE ISSUED AT 1009 AM EDT SAT JUN 15 2013 13Z MESOANALYSIS SHOWS A NORTHWEST-SOUTHEAST ORIENTED RIDGE AXIS RUNNING FROM THE EASTERN SHORE OF LAKE SUPERIOR...ACROSS LAKE HURON AND DOWN INTO EASTERN OHIO. BROKEN-OVERCAST MID CLOUD DECK HAS OVERSPREAD NORTHERN MICHIGAN...NOT MUCH ON RADAR OVER THE IMMEDIATE AREA WITH SOME VERY LIGHT RAIN SHOWERS MOVING ACROSS CENTRAL UPPER MICHIGAN THOUGH RADAR LOOPS SHOW THIS DRIVEN BY A COMPACT MESOSCALE VORTICITY CENTER. 12Z APX SOUNDING SHOWS SATURATION IN THE 650- 550MB LAYER BUT IS QUITE DRY BELOW (36C DEW POINT DEPRESSION AT 850MB). IMMEDIATE NOWCAST CHANGES TO FORECAST WILL BE TO INCREASE CLOUD COVER... AND ADD IN SOME VERY LIGHT RAIN SHOWERS (OR MOSTLY SPRINKLES) TO MUCH OF EASTERN UPPER AND NORTH OF A TVC-OSC LINE IN NORTHWEST LOWER (MOSTLY AFTER 16Z). UPDATE ISSUED AT 700 AM EDT SAT JUN 15 2013 WIDELY SCATTERED MID LEVEL RETURNS CONTINUE TO DRIFT SOUTH OF OUR CWA EARLY THIS MORNING PER LATEST KAPX 88D BASE REF LOOP. ALL CIGS REMAIN ABOVE 10 KFT SO FAR TODAY...BUT DO EXPECTED SOME LOW CLOUD DEVELOPMENT AS WE HEAD INTO THIS AFTERNOON IN RESPONSE TO GRADUALLY INCREASING LOW LEVEL MOISTURE AHEAD OF WEAK LOW PRESSURE TRACKING TOWARD MICHIGAN. PRECIP CHANCES WILL GRADUALLY INCREASE TOWARD AFTERNOON AS WELL...BUT ANY SHOWER OR THUNDERSTORM ACTIVITY WILL REMAIN SCATTERED...WITH BETTER CHANCES AND HEAVIER PRECIP REMAINING SOUTH OF OUR CWA. HAVE MADE SOME ADJUSTMENTS TO CLOUD COVER BASED ON LATEST IR SATELLITE LOOP. OTHERWISE...CURRENT FORECAST HIGHLIGHTS INCREASING SMALL CHANCES OF SHOWERS/STORMS THIS AFTERNOON...WHICH IS STILL ON TARGET. && .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 250 AM EDT SAT JUN 15 2013 FIRST OF ALL...HATS OFF TO OLD MOTHER NATURE...DELIVERING ONE OF THE FINER SUMMER DAYS YOU WILL SEE AROUND THESE PARTS YESTERDAY. DRY AIRMASS RESPONSIBLE FOR SUCH FANTASTIC WEATHER STILL FIRMLY IN CONTROL AT THIS EARLY HOUR...WITH EXPANSIVE SURFACE HIGH PRESSURE EXTENDING FROM THE NORTHERN LAKES RIGHT DOWN INTO THE SOUTHEASTERN STATES. 00Z RAOB PWAT ANALYSIS CONFIRMS SUCH...WITH CP AIRMASS BRINGING SUB ONE INCH PWAT VALUES ACROSS THIS SAME REGION (RATHER IMPRESSIVE FOR THIS TIME OF YEAR). UNFORTUNATELY...ONE DOES NOT HAVE TO VENTURE TOO FAR WEST FOR SOME INCLEMENT WEATHER. BACKSIDE RETURN FLOW ALREADY AMPING UP ACROSS THE WESTERN LAKES...WITH REAL-TIME OBS AND HIGH RES RUC ANALYSIS SHOWING ELEVATED MOISTURE PLUME ALREADY PUNCHING THROUGH WISCONSIN AND WESTERN UPPER MICHIGAN. LEADING MOISTURE CONVERGENCE AXIS AND SUBTLE WAVE PIVOTING THROUGH BROADER UPSTREAM RIDGING MANAGED TO KICK OFF SOME EVENING SHOWERS AND STORMS TO OUR NORTHWEST...ALTHOUGH THESE HAVE LARGELY DIED OUT AS THEY APPROACH OVERHEAD DEEP LAYER DRY WEDGE. THEME OF THIS SUMMER CONTINUES...WITH THE MOST PROMINENT AREA OF SHOWERS AND STORMS REMAINING SAFELY TO OUR SOUTHWEST WHERE NOCTURNALLY CHARGED LOW LEVEL JET FORCED MASS CONVERGENCE AND DEEP INSTABILITY ARE BETTER JUXTAPOSED. RADAR AND SATELLITE TRENDS BOTH SUGGEST THIS SHOULD REMAIN THE CASE RIGHT THROUGH THE EARLY MORNING HOURS...LEAVING MOSTLY DRY CONDITIONS ACROSS OUR AREA THROUGH AT LEAST THE FIRST HALF OF THE MORNING. SHORT TERM FORECAST CONCERNS CENTER ON POSSIBLE ADDITIONAL SHOWER AND STORM DEVELOPMENT TODAY AND TONIGHT. GOING TO BE AWFULLY HARD TO BEAT YESTERDAY...AND......WE WON'T. THAT SAID...UPSTREAM TRENDS AND PATTERN RECOGNITION SUPPORTS A NOT-TO-SHABBY START TO THE WEEKEND. REMAIN LARGELY UNENTHUSED WITH RAIN CHANCES TODAY...DESPITE STAGE RIGHT DEPARTURE OF CURRENT SURFACE HIGH. UPSTREAM MID LEVEL RIDGING REPLACES ITS SURFACE LIKENESS...ALTHOUGH DEAMPLIFYING AS IT DOES SO WITH ENERGY CUTTING ACROSS SOUTHERN CANADA. UPPER LEVEL FORCING ARRIVES LATE VIA RER UPPER JET DYNAMICS...MOST OF WHICH HOLDS OFF UNTIL THE OVERNIGHT HOURS. PER THE USUAL...GUIDANCE JUST SEEMS MUCH TOO AGGRESSIVE DRIVING LOW LEVEL MOISTURE THIS FAR NORTH...ESPECIALLY GIVEN ANTECEDENT DRY CONDITIONS AND PROPENSITY FOR MOISTURE STEALING CONVECTION TO CONTINUE TO FIRE WELL TO OUR SOUTHWEST. MODIFYING MODEL SUGGESTED SOUNDINGS FOR SUCH SHOWS SIGNIFICANT MID LEVEL CAP UNTIL VERY LATE...AND LITTLE...IF ANY ML CAPE DEVELOPMENT. CORE OF MORE IMPRESSIVE MID LEVEL LAPSE RATES REMAINS JUST UPSTREAM ACROSS WISCONSIN. THETA-E RIDGING DOES ADVANCE EAST WITH TIME....CROSSING OUR AREA LATE MORNING THROUGH THE AFTERNOON. EVEN THIS...HOWEVER... WILL BE LOSING DEFINITION WITH TIME. NO DOUBT CLOUDS WILL BE ON THE INCREASE AS UPSTREAM MID LEVEL MOISTURE PLUME ADVANCES EAST...BUT GIVEN ALL THE ABOVE...THE PROSPECTS FOR ANY MEANINGFUL RAINS ARE MUCH LESS THAN IDEAL. SUPPOSE A SPRINKLE/VERY LIGHT SHOWER IS PLAUSIBLE ALONG THETA-E GRADIENT OR FROM WHAT'S EVER LEFT OF UPSTREAM ACTIVITY. TEMPTED TO PULL POPS ALTOGETHER...BUT GIVEN SOME LINGERING UNCERTAINTY...WILL JUST SIMPLY MAINTAIN INHERITED LOW CHANCE MENTION. DESPITE CLOUDS...THERMAL PROFILES SUPPORT A RATHER MILD DAY...WITH HIGHS WELL INTO THE 70S ACROSS MOST AREAS. LIGHT PRESSURE GRADIENT SUPPORTS LATE MORNING AND AFTERNOON LAKE BREEZE DEVELOPMENT...KEEPING SHORELINE AREAS A FEW DEGREES COOLER. THINGS TRY TO CONGEAL TO BRING BETTER RAIN CHANCES TONIGHT...WITH SOMEWHAT DEEPER LOW LEVEL MOISTURE OVERTOPPED BY UPPER JET DYNAMICS. NOTHING OVERLY IMPRESSIVE THROUGH THE MID LEVELS...WITH PERHAPS A CONVECTIVELY AUGMENTED VORT LOBE/SUBTLE WAVE RACING EAST ACROSS THE SOUTHERN THIRD OF THE AREA. PATTERN RECOGNITION CONTINUES TO SUPPORT SOUTHERN LAKES/NORTHERN OHIO VALLEY MCS DEVELOPMENT ON NOSE OF STRONGER LOW LEVEL JET. SOME GUIDANCE SEEMS OVERLY AGGRESSIVE DRIVING CONVECTIVE DEVELOPMENT NORTH...ESPECIALLY THE 00Z GFS AND 12Z ECMWF. DEEP LAYER FLOW SIMPLY DOES NOT BACK ENOUGH TO SUPPORT THESE NORTH BASED TRENDS. CONVECTIVE EVOLUTION TODAY WILL HAVE PLENTY TO SAY ON OVERALL MASS FIELDS...BUT LARGE SCALE PATTERN FULLY SUPPORTS A MORE SOUTH BASED PASSAGE TO ANY MCS TONIGHT...WITH JUST SOME LIGHTER ACTIVITY THIS FAR NORTH. WILL TREND POPS AS SUCH...BUT STILL LEAVE PLENTY OF OPPORTUNITY FOR FUTURE ADJUSTMENTS BASED ON THIS AFTERNOONS UPSTREAM TRENDS. A MILD NIGHT...WITH LOWS IN THE 50S AND LOWER 60S. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 250 AM EDT SAT JUN 15 2013 SUNDAY AND MONDAY...A WEAK AREA OF LOW PRESSURE WILL SLIDE EAST THRU MICHIGAN EARLY SUNDAY MORNING. THIS LOW WILL GRADUALLY MERGE WITH ANOTHER NRN STREAM LOW DROPPING SE INTO MICHIGAN SUNDAY AFTERNOON AND EVENING. A COLD FRONT ASSOCIATED WITH THE SECOND LOW PRESSURE SYSTEM WILL DROP INTO NRN MICHIGAN SUNDAY NIGHT...AND WILL THEN SWEEP THRU LWR MICHIGAN ON MONDAY. LATEST NAM APPEARS TO BE TOO FAST WITH THE PASSAGE OF THIS FRONT CONSIDERING THE FRONT BECOMES ORIENTED WEST TO EAST ALONG THE UPPER LEVEL FLOW ONCE IT REACHES UPPER MICHIGAN. ECMWF PROVIDES A SLOWER AND THUS MORE REASONABLE SOLUTION...AND WILL LEAN IN THIS DIRECTION. CHANCE OF SHOWERS/STORMS WILL LINGER INTO SUNDAY MORNING FOR MUCH OF OUR CWA AS THE INITIAL SURFACE LOW EXITS LWR MICHIGAN. DIURNAL INSTABILITY COMBINED WITH WEAK LAKE BREEZE BOUNDARIES AND LINGERING LOW LEVEL MOISTURE TO PROVIDE SMALL CHANCES OF SHOWERS AND STORMS FOR ERN UPR AND NE LWR MICHIGAN SUNDAY AFTERNOON. SECONDARY SURFACE LOW AND ASSOCIATED COLD FRONT WILL DROP INTO ERN UPR AND FAR NRN LWR MICHIGAN SUNDAY AFTERNOON/EVENING...PROVIDING ADDITIONAL FOCUS FOR CONVECTIVE DEVELOPMENT TO PERSIST THRU THE NIGHT ACROSS LOCATIONS ALONG AND NORTH OF M-32. BY MONDAY...THE SLOW-MOVING COLD FRONT WILL DROP THRU THE REST OF OUR CWA...RESULTING IN CONTINUED CONVECTIVE DEVELOPMENT THRU THE DAY. CHANCES OF SHOWERS AND STORMS WILL COME TO AN END THRU MONDAY NIGHT AS THE COLD FRONT EXITS LWR MICHIGAN. TUESDAY THRU FRIDAY...STRONG CANADIAN HIGH PRESSURE...SUBSIDENCE AND DRY AIR WILL BUILD INTO THE GREAT LAKES TUESDAY INTO WEDNESDAY BEHIND THE DEPARTING COLD FRONT. DRY WEATHER IS EXPECTED THRU THIS TIME PERIOD...WITH TEMPS SEVERAL DEGREES BELOW NORMAL THANKS TO CAA. WEAK AREA OF LOW PRESSURE WILL SLOWLY TRACK THRU ONTARIO AND INTO QUEBEC WEDNESDAY NIGHT THRU FRIDAY...DRAGGING THE SRN END OF A WEAK FRONT THRU NRN MICHIGAN. BOTH MOISTURE AND LIFT WILL BE LIMITED WITH THIS WEAK FEATURE...BUT WILL INTRODUCE SMALL PRECIP CHANCES INTO THE FORECAST FOR THIS TIMEFRAME AS THIS FRONT PASSES THRU THE REGION. TEMPS WILL REBOUND TO NEAR NORMAL IN WEAK WAA AHEAD OF THIS FRONT. INITIAL LOOK FOR NEXT WEEKEND SUGGESTS MAINLY DRY WEATHER WITH NEAR NORMAL TEMPS. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 158 PM EDT SAT JUN 15 2013 VFR CONDITIONS THROUGH THE AFTERNOON...SOME MVFR VISIBLITIES WITH RAIN SHOWERS TONIGHT AND A PERIOD OF MVFR/IFR CEILINGS OVERNIGHT THAT WILL MIX OUT SUNDAY MORNING. && .MARINE... ISSUED AT 250 AM EDT SAT JUN 15 2013 LIGHT WINDS CONTINUE...WITH LOCAL LAKE BREEZE DEVELOPMENT THIS AFTERNOON...ESPECIALLY OFF LAKE HURON. WEAK SURFACE TROUGH PASSES THROUGH THE REGION LATE TONIGHT INTO EARLY SUNDAY...VEERING SOUTHWEST FLOW TO WESTERLY. MARINE FOG EXPECTED TO DEVELOP LATER TONIGHT INTO SUNDAY AS LOW LEVEL MOISTURE ADVECTION STRENGTHENS. SHOWERS AND STORMS POSSIBLE TONIGHT...ALTHOUGH STRONGEST ACTIVITY EXPECTED TO REMAIN ACROSS THE SOUTHERN LAKES. EARLY INDICATIONS ARE FOR MAINLY LIGHT WINDS TO CONTINUE RIGHT THROUGH MUCH OF NEXT WORK WEEK. && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LH...NONE. LM...NONE. LS...NONE. && $$ UPDATE...JPB SYNOPSIS...MLR SHORT TERM...MSB LONG TERM...MLR MARINE...MSB