610 FXUS63 KAPX 132331 AFDAPX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 731 PM EDT SAT JUL 13 2013 .SYNOPSIS... ISSUED AT 345 PM EDT SAT JUL 13 2013 A DOMINATING AREA OF HIGH PRESSURE OVER THE EASTERN THIRD OF THE COUNTRY...WILL REMAIN CENTERED ALONG THE ATLANTIC SEABOARD FOR THE NEXT SEVERAL DAYS. THIS PATTERN WILL GENERATE EXTREMELY WARM TEMPERATURES WITH INCREASING HUMIDITY LEVELS ACROSS THE GREAT LAKES THROUGH THE WEEKEND. TEMPERATURES ARE ACTUALLY EXPECTED TO WARM INTO THE LOWER 90S TO START THE UPCOMING WORK WEEK. CHANCES OF SHOWERS AND STORMS WILL ENTER OUR WEATHER PICTURE BY MIDWEEK...AS A WEAK COOL FRONT SWEEPS THROUGH THE GREAT LAKES. && .UPDATE... ISSUED AT 730 PM EDT SAT JUL 13 2013 FLAT CU FIELD DIMINISHING ON SCHEDULE. NO CHANGES OF SUBSTANCE MADE TO THE FORECAST FOR NOW. && .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 345 PM EDT SAT JUL 13 2013 AFTERNOON SURFACE ANALYSIS SHOWS HIGH PRESSURE EXTENDING FROM NEW ENGLAND/SOUTHERN QUEBEC WESTWARD INTO THE UPPER GREAT LAKES...COLD FRONT STRETCHES FROM HUDSON BAY SOUTHWEST INTO NORTH DAKOTA/ MONTANA. UPPER RIDGE AXIS CROSSES THE GREAT LAKES AS WELL... "BRIDGING" CLOSED ANTICYCLONES OVER THE CENTRAL PLAINS AND OFF THE LONG ISLAND COAST WHILE AN UPPER LOW RETROGRADES WEST ALONG THE OHIO RIVER. LATTER UPPER HIGH FORECAST TO BUILD WEST AND ENCOMPASS LOWER MICHIGAN BY SUNDAY AFTERNOON...WHILE SURFACE RIDGING HANGS ON AS WELL. THE RESULT IS MINIMAL FORECAST CONCERNS OUTSIDE OF HIGH TEMPERATURES SUNDAY AFTERNOON. TONIGHT/SUNDAY: WEATHER...SCATTERED CUMULUS ACROSS INTERIOR NORTHERN LOWER AT MID AFTERNOON WILL DISSIPATE WITH LOSS OF HEATING...THICKER BAND OF CLOUDS ACROSS WESTERN UPPER AND MUCH OF WESTERN/CENTRAL LAKE SUPERIOR SHOULD GET NUDGED NORTHWARD OVERNIGHT AS MID LEVEL WINDS BACK WITH RISING HEIGHTS AS ATLANTIC UPPER RIDGE BUILDS WESTWARD. PLENTY OF SUN FOR SUNDAY. WINDS...BECOMING LIGHT SOUTHERLY/VARIABLE THIS EVENING WITH DECOUPLING (ESPECIALLY ACROSS NORTHERN LOWER)...GENERALLY SOUTH/ SOUTHWEST WINDS FOR SUNDAY UNDER 10 MPH NORTHERN LOWER AND 5-15 MPH EASTERN UPPER...LAKE BREEZES WILL TURN WINDS OFF THE WATER AROUND THE NORTHWEST LOWER SHORELINE. TEMPERATURES...SEASONABLE 50S FOR LOWS TONIGHT...SHOULD BE ABLE TO TACK ON A COUPLE DEGREES TO TODAY'S HIGHS FOR SUNDAY...SO MORE WIDESPREAD 80S EXPECTED AWAY FROM THE LAKES. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 345 PM EDT SAT JUL 13 2013 LOOKS TO BE NO STOPPING NOW WELL ADVERTISED DEVELOPMENT OF A MINI NORTHERN MICHIGAN HEAT WAVE HEADING INTO THE UPCOMING WORK WEEK. PATTERN RECOGNITION FULLY SUPPORTS SUCH...WITH CURRENT WESTERN ATLANTIC RIDGING RETROGRADING AND STRENGTHEN TO A 595+ HEIGHT ANTICYCLONE OVER THE NORTHERN OHIO VALLEY MONDAY THROUGH WEDNESDAY. OVERHEAD LOWER AND MIDDLE 590 HEIGHTS NOTHING TO SNEEZE AT...WITH MULTI-DAY SUSTAINED W-SW OFF THE DECK FLOW TAPPING INTO AT LEAST SOME OF THE CENTRAL PLAINS HEAT DOME. RECORD SETTING HEAT IT APPEARS NOT TO BE...BUT WITH H85 TEMPERATURES PROGGED TO REACH THE UPPER TEENS...LOWER 90S APPEAR EASILY ATTAINABLE FOR AT LEAST PARTS OF THE AREA EACH AFTERNOON MONDAY THROUGH WEDNESDAY. WHILE DON'T SEE A DIRECT TAP TO WESTERN GULF OF MEXICO MOISTURE...GRADUAL MOISTURE POOLING AND NEAR PEAK EVAPOTRANSPIRATION WILL HELP DEW POINTS SPIKE WELL INTO THE 60S (IF NOT LOWER 70S). THIS SETS THE STAGE FOR APPARENT TEMPERATURES TO FEEL SEVERAL DEGREES HOTTER THAN ACTUAL HIGHS...MAKING FOR SOME VERY UNCOMFORTABLE CONDITIONS. RATHER SIGNIFICANT CHANGES IN THE PATTERN EXPECTED TOWARDS THE END OF WEEK/INTO THE START OF NEXT WEEKEND... WITH TROUGHING DIGGING BACK ACROSS THE LAKES...DRIVING A RATHER SIGNIFICANT COLD FRONT SOUTH ACROSS THE REGION. THIS WILL BRING OUR BEST BET FOR SOME MUCH NEEDED RAINFALL AS MID LEVEL HEIGHTS LOWER...ALONG WITH A RETURN TO MUCH MORE TOLERABLE TEMPERATURES. FORECAST CONCERNS THROUGH THE EXTENDED CENTER ON SHEDDING A TOUCH MORE INSIGHT TO ALL THE ABOVE. INCREASINGLY HOT...HUMID...AND MOSTLY DRY ABOUT SUMS UP THE WEATHER HEADING INTO MID WEEK. DEEP LAYER HIGH PRESSURE REMAINS CENTERED ACROSS THE REGION...FORCING SHOWER/STORM PRODUCING BAROCLINIC AXIS WELL TO OUR NORTH AND WEST. H85 TEMPERATURES BEGIN THE TREND UPWARD...MAXING OUT IN THE UPPER TEENS BY TUESDAY AND WEDNESDAY. SEE LITTLE REASON NOT TO MIX OUT AT LEAST THROUGH THIS LAYER...WHICH SUPPORTS HIGH TEMPERATURES NEAR 90 FOR SOME MONDAY...AND UP INTO THE LOWER 90S TUESDAY AND WEDNESDAY AFTERNOONS. PER THE USUAL...WARMEST READINGS WILL BE FOUND ACROSS THE INTERIOR OF NORTHERN LOWER...WITH LAKE MODIFICATION HELPING KEEP NEARSHORE AREAS AND LOCATION NORTH OF THE BIG BRIDGE A TOUCH LESS OPPRESSIVE. HEAT INDICES BEGIN TO SPIKE... ESPECIALLY TUESDAY AND WEDNESDAY AFTERNOON WHEN DEW POINTS REACH INTO THE UPPER 60S AND LOWER 70S. MUGGIEST WEATHER EXPECTED ON THE SOUTH SIDE OF THE SUNRISE SIDE CLOSER TO MAX AREA OF EVAPOTRANSPIRATION FROM LOWER MICHIGAN CORN BELT. HERE...WOULD EXPECT APPARENT TEMPERATURES TO AT LEAST APPROACH HEAT ADVISORY CRITERIA (HEAT INDICES OF AT LEAST A 100 FOR A PERIOD OF 3 HOURS OR MORE). NOT MUCH BETTER ELSEWHERE...WITH WIDESPREAD LOWER AND MIDDLE 90 DEGREE HEAT INDICES ACROSS INTERIOR NORTHERN LOWER MICHIGAN. AS MENTIONED...AND UNFORTUNATELY...THIS SHOULD ALSO MAINLY BE A DRY PATTERN WITH SUCH HIGH MID LEVEL HEIGHTS AND LACK OF ANY APPRECIABLE TRIGGER. MODEL DERIVED SOUNDINGS STARTING TO SHOW SOME RATHER IMPRESSIVE ML CAPE DEVELOPMENT DURING PEAK AFTERNOON HEATING...WITH VALUES AOA 1.5 J/KG FOR SOME. THIS IS LIKELY A TOUCH OVERDONE...WITH GUIDANCE A TOUCH TOO AGGRESSIVE DRIVING SURFACE DEWPOINTS UPWARD. EITHER WAY...APPEARS TO BE AT LEAST SOME FUEL FOR LAKE INDUCED BOUNDARIES TO KICK OFF SOME ISOLATED MOIST CONVECTION. GIVEN CURRENT DRY PATTERN AND INHERENT MESOSCALE FORECAST DIFFICULTIES...PREFER TO LEAVE THIS POSSIBILITY OUT OF THE FORECAST. ONE EXCEPTION... HOWEVER...WILL BE ACROSS EASTERN UPPER WEDNESDAY AFTERNOON...WHERE LOWERING HEIGHTS LOOK TO HELP THE CONVECTIVE CAUSE. INCREASING SUPPORT FOR A PATTERN REALIGNMENT HEADING INTO WEDNESDAY NIGHT AND BEYOND...WITH REESTABLISHMENT OF INTERMOUNTAIN WEST RIDGING AND SUBSEQUENT ARRIVAL OF LOWERING HEIGHTS ACROSS THE GREAT LAKES. TIMING STILL SUBJECT TO CHANGE...OF COURSE...BUT PERUSAL OF AVAILABLE MID RANGE GUIDANCE SUGGESTS COLD FRONTAL PASSAGE WEDNESDAY NIGHT (GO FIGURE...ANOTHER OVERNIGHT FRONTAL PASSAGE :)). FORCING ALONG THIS FRONT NOT OVERLY IMPRESSIVE...ALTHOUGH THERE IS SOME SEMBLANCE OF ATTENDANT DIVERGENCE POCKET TIED TO UPPER JET RER QUAD. UNFAVORABLE TIMING ONLY ADDING TO THE UNCERTAINTY IN RAIN COVERAGE...SO A SIMPLE CHANCE WORDING WILL SUFFICE FOR NOW. ADDITION HARD TO TIME WAVES EXPECTED TO PINWHEEL THROUGH THE REGION INTO THE START OF NEXT WEEKEND. MODEL BLEND APPROACH JUST TOO AGGRESSIVE WITH RAIN CHANCES...HOWEVER...ESPECIALLY GIVEN TIMING AND MOISTURE AVAILABILITY UNCERTAINTIES. AS IS OFTEN THE CASE DURING THE SUMMER...FORECAST WILL SEEM MUCH WETTER THAN IT ACTUALLY WILL BE...WITH EXTENDED DRY PERIODS MORE THAN EXPECTED DURING THIS PERIOD. ONE THING APPEARS INCREASINGLY CERTAIN...AND THAT IS A TREND TOWARDS MUCH MORE TOLERABLE TEMPERATURES. TEMPERATURES LOOK TO COOL OFF HEADING INTO THE WEEKEND...WITH 80+ DEGREE HIGHS THURSDAY GIVEN WAY TO READINGS BACK DOWN INTO PERHAPS THE LOWER AND MIDDLE 70S BY SATURDAY. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING) ISSUED AT 730 PM EDT SAT JUL 13 2013 VFR...OUTSIDE OF SOME GROUND FOG AT MBL LATE TONIGHT. VERY LITTLE IS CHANGING ACROSS THE NORTHERN LAKES...AS HIGH PRESSURE NOSES IN FROM THE EAST. LIGHT SOUTHERLY WINDS AT THE LOW LEVELS ARE VERY SLOWLY BRINGING IN WARMER AND MORE HUMID AIR. SOME THIN GROUND FOG COULD FORM AT MBL TONIGHT...ONLY HAVE MVFR VSBYS IN A TEMPO GROUP FOR NOW. A FEW CUMULUS ARE EXPECTED AGAIN ON SUNDAY. LIGHT WINDS TONIGHT. A LIGHT SOUTH BREEZE EARLY SUNDAY WILL GIVE WAY TO LAKE BREEZES LATER IN THE DAY. && .MARINE... ISSUED AT 345 PM EDT SAT JUL 13 2013 LAKE BREEZE CIRCULATIONS WILL DIMINISH THIS EVENING BUT WILL RAMP UP AGAIN FOR SUNDAY...MAINLY NOTICEABLE AROUND THE NORTHEAST LOWER NEARSHORE ZONES WHERE WINDS WILL TAKE ON AN EASTERLY COMPONENT OFF LAKE HURON. NO HEADLINES EXPECTED THROUGH SUNDAY NIGHT. && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LH...NONE. LM...NONE. LS...NONE. && $$ UPDATE...JZ SYNOPSIS...KB SHORT TERM...JB LONG TERM...MB AVIATION...JZ MARINE...JB