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000
FXUS63 KAPX 192342
AFDAPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
742 PM EDT SUN MAY 19 2013

.SYNOPSIS...
ISSUED AT 340 PM EDT SUN MAY 19 2013

A STORM SYSTEM WILL ORGANIZE OVER THE PLAINS...BEFORE MOVING INTO
THE GREAT LAKES TO START THE WORK WEEK. THIS APPROACHING SYSTEM WILL
GENERATE SHOWERS AND THUNDERSTORMS ACROSS NORTHERN MICHIGAN THROUGH
MID WEEK.

&&

.UPDATE...
ISSUED AT 742 PM EDT SUN MAY 19 2013

RECENTLY DEVELOPED CU FIELD HAS DECIDED TO BE RATHER
TRANSIENT...RACING OFF INTO N CENTRAL LOWER MI. THERE ARE SOME CU
LINES LEFT BEHIND IN NW LOWER. THERE IS PERHAPS A VERY SLIGHT
CHANCE FOR THESE TO DEVELOP INTO CONVECTION BETWEEN 00Z AND 03Z IF
THE CAP WEAKENS AS MUCH AS PROGGED BY THE NAM (SEE EARLIER
UPDATE). WILL CONTINUE TO CHASE CLOUD TRENDS...OTHERWISE NO
CHANGES.

UPDATE ISSUED AT 635 PM EDT SUN MAY 19 2013

SOME INTERESTING TRENDS OVER THE LAST HOUR OR SO. 1ST...CU FIELD
OVER THE INTERIOR OF NORTHERN LOWER MI CONTINUES TO DIMINISH...NOW
LARGELY CONFINED TO MIO AND THE SURROUNDING AREA. RAPIDLY RUNNING
OUT OF TIME TO SEE ANYTHING FIRE THERE.

2ND...A HIGH-BASED CU FIELD HAS RAPIDLY DEVELOPED ALONG THE LAKE
MI COAST WEST OF TVC OVER THE PAST HOUR. OBVIOUSLY NOT DIRECTLY
ASSOCIATED WITH DIURNAL HEATING...GIVEN THE LOCATION OVER THE
MARINE LAYER. A FEW SHORT-TERM MODEL SOUNDINGS (LED OF COURSE BY
THE NAM) ARE SHOWING ENOUGH MOISTURE ADVECTION INTO THE 850-800MB
LAYER TO PRODUCE SATURATION. THE NAM ALSO LEADS THE WAY IN THE
RESULTING ELEVATED INSTABILITY...WITH MUCAPES NEARING 1K J/KG BY
03Z...AND A WEAKENING OF THE CAP (10C 750MB TEMPS OFF THE NAM...12C
FROM THE RUC/LOCAL WRF). THOUGH THE NAM IS MOIST TO A FAULT...IT
DOES AT LEAST REFLECT THE CLOUD DEVELOPMENT THAT WE ARE SEEING IN
THE AREA. AND IT WOULD SUGGEST THAT ANY SORT OF WEAK IMPULSE
(SAY...EXPELLED BY THE DYING CLUSTER OF CONVECTION NEAR LK
WINNEBAGO) MIGHT KICK SOMETHING OFF.

AM INCREASING CLOUD COVER...BUT /FOR NOW/ WILL NOT INTRODUCE POPS
ANY EARLIER THAN IS ALREADY IN THE FORECAST (06Z/2AM).
HOWEVER...WILL TAKE A VERY CLOSE LOOK AT 00Z GRB/APX SOUNDINGS AND
OTHER DATA THAT IS SOON TO ARRIVE...IN PARTICULAR LOOKING AT HOW
THE CAP MIGHT BEHAVE THIS EVENING.

&&

.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 340 PM EDT SUN MAY 19 2013

POSSIBLY AN ISOLATED EARLY EVENING SHOWER OVER INTERIOR AREAS MAINLY
INVOF LAKE BREEZE BOUNDARIES. THESE SHOULD DISSIPATE EARLY WITH LOSS
OF DAYTIME HEATING.  AN ELEVATED WARM FRONT LIFTS THROUGH THE REGION
LATE TONIGHT /AFTER 06Z/...WITH SURFACE FRONTAL BOUNDARY DRAPED
ACROSS THE AREA.  UNIMPRESSIVE KINEMATICS...WITH BEST FORCING
REMAINING WEST OF THE AREA CLOSER TO UPPER TROUGH. 850M THETA-E
RIDGE FOLDS OVER INTO THE AREA LATE TONIGHT WITH STEEPER MID LEVEL
LAPSE RATES AND MUCAPES OVER 500 J/KG. THIS ALL POINTS TO AT LEAST
A CHANCE OF THUNDER OVER NRN/WRN AREAS. FAIRLY MILD...WITH LOWS
IN THE 50S NORTH TO 60S SOUTH. WILL ALSO ADD FOG FOR LATER TONIGHT TO
NEARSHORE WATERS AND PORTIONS OF NORTHERN LOWER MICHIGAN...AS LOW
LEVEL MOISTURE CONTINUES TO INCREASE AND POOL INVOF BOUNDARY.

MONDAY...CHALLENGING FORECAST GIVEN QUESTIONABLE EVOLUTION OF
UPSTREAM CONVECTION.  PRECIP CHANCES WILL CONTINUE TO INCREASE FROM
WEST TO EAST WITH FRONTAL BOUNDARY DRAPED ACROSS NRN LOWER
MICHIGAN.  DEEPENING TROUGH/LOW PRESSURE IN THE PLAINS WILL BEGIN TO
TAP INTO GULF MOISTURE...ADVECTING DEEPER MOISTURE NORTHWARD THRU
THE LOWER AND MID MISSISSIPPI VALLEY AND INTO THE WRN GREAT LAKES.
AS THIS DEEPER MOISTURE BEGINS TO INTERACT WITH FRONTAL BOUNDARY AND
A SERIES OF SHORT WAVES RIDING NE THRU MICHIGAN AHEAD OF THE
DEEPENING UPPER LOWER...SHOWER AND THUNDERSTORM ACTIVITY WILL
INCREASE.  DIFFICULT TO PINPOINT EXACT DETAILS GIVEN UNCERTAINTY IN
FRONTAL LOCATION/CONVECTIVE EVOLUTION...BUT BROAD LARGE-SCALE ASCENT
ON THE ERN EDGE OF UPPER TROUGH AND AIRMASS DESTABILIZATION SHOULD
RESULT IN A GOOD CHANCE OF SHOWERS/STORMS FOR THE AFTN HOURS.
BACKWARD TRAJECTORY OF DWPTS SHOW PARCEL ORIGINATION FROM CENTRAL
INDIANA FOR MONDAY AFTN...WHICH BRINGS SFC DWPTS INTO THE LOWER
60S FOR PORTIONS OF THE AREA MONDAY AFTERNOON. MODIFYING FCST
SOUNDINGS FOR A PARCEL TEMP OF 79/62 YIELD SBCAPES OF 1200 J/KG.
WITH STEEPENING MID LEVEL LAPSE RATES ARRIVING OVER SOUTHWEST
AREAS LATE IN THE DAY AND STRONG BOUNDARY LAYER HEATING
/DESTABILIZATION/...AN ISOLATED SEVERE THUNDERSTORM POSSIBLE WITH
THE MAIN THREAT BEING LARGE HAIL. HIGH TEMPERATURES ANOTHER
CHALLENGE GIVEN CLOUD/PCPN UNCERTAINTY AND WILL BASICALLY TAKE A
MODEL BLEND...WHICH GIVES HIGHS IN THE UPPER 60S OVER ERN UPPER TO
THE LOWER 80S SOUTH. WITH ENOUGH SUNSHINE...TEMPS ALOFT CERTAINLY
WARM ENOUGH TO SUPPORT HIGH TEMPS IN THE MID 80S SOUTH OF M-72.

.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 340 PM EDT SUN MAY 19 2013

INCREASINGLY AMPLIFIED AND SLOW MOVING PATTERN LOOKS TO LOCK IN A
RATHER WET PERIOD OF WEATHER RIGHT THROUGH MID-WEEK. IMPETUS BEHIND
THE RAINS WILL BE PERSISTENT MOISTURE RICH LOW AND MID LEVEL
CONVERGENCE ZONE LAYING OUT ACROSS THE AREA...ALL THE WHILE SLOW
MOVING CENTRAL PLAINS LOW SENDS VARIOUS POCKETS OF ENERGY UP ALONG
IT. FROM A CONCEPTUAL STANDPOINT...MOISTURE SUPPLY LOOKS RATHER
IDEAL...WITH WIDE OPEN GULF OF MEXICO MOISTURE FEED SPIKING PWAT
VALUES UP TO AND EXCEEDING AN INCH AND A HALF RIGHT THROUGH
WEDNESDAY. THAT SAID...CONVECTIVE SEASON NOW IN OVERDRIVE TO OUR
SOUTH AND SOUTHWEST...AND WILL NO DOUBT HAVE PLENTY TO SAY ON THE
OVERALL EVOLUTION OF THIS EVENT. EARLY MEMORIAL DAY WEEKEND GUIDANCE
TRENDS CONTINUE TO INDICATE DEVELOPMENT OF RATHER DEEP WEST/EAST
COAST TROUGHS...WITH HIGH PLAINS RIDGING TUCKED UP IN-BETWEEN. THIS
SHOULD...THEORETICALLY...OPEN THE DOOR FOR A SHOT OF RATHER COOL
CANADIAN AIR AND PERHAPS THE POTENTIALLY FOR ANOTHER OVERNIGHT FROST
EVENT...ESPECIALLY FOR FRIDAY NIGHT. ABOVE YIELDS PLENTY TO TALK
ABOUT...WITH MUCH OF THE FOCUS CENTERED ON IMPENDING WET WEATHER AND
SEVERE WEATHER POTENTIAL.

AS MENTIONED...UPCOMING SET-UP LOOKS RATHER FAVORABLE FOR SOME MUCH
NEEDED RAINS...WITH PERSISTENT MOIST SOUTH FLOW ON FRONT SIDE OF
SLOW MOVING CENTRAL PLAIN LOW PRESSURE INTERSECTING LOW/MID LEVEL
BAROCLINIC AXIS. SURFACE WARM FRONT LOOKS TO GRADUALLY MIX SOUTH
MONDAY NIGHT...AIDED BY COLD LAKE WATERS AND PERIODIC BOUTS OF
CONVECTION...BEFORE PERHAPS BEING PROPELLED BACK NORTH TUESDAY INTO
WEDNESDAY WITH APPROACH OF PRIMARY UPSTREAM WAVE. HARD TO TIME
PERIODS OF BETTER SHOWER AND STORM POTENTIAL...ESPECIALLY WITH
UPSTREAM CONVECTIVE TRENDS AND TIMING OF VARIOUS IMPULSES DICTATING
SUCH. DESPITE PERSISTENCE FOR RAINS SEEN IN GUIDANCE...PREFER TO
KEEP JUST LIKELY WORDING IN THE FORECAST (LEARNED UP HERE TO
NEVER...NEVER TRUST CONVECTION). INITIAL SEVERE THREAT SHOULD REMAIN
TO OUR SOUTHWEST MONDAY NIGHT WHERE MORE PRONOUNCED LOW LEVEL
INSTABILITY AXIS AND DEEPER SHEAR ARE BETTER JUXTAPOSED. INCREASING
CONCERN FOR AT LEAST A MINIMAL SEVERE THREAT HEADING INTO TUESDAY
AND WEDNESDAY AS SURFACE WARM FRONT KICKS BACK NORTH...PERHAPS
REACHING AS FAR NORTH AS THE STRAITS BY WEDNESDAY. MUCH TOO EARLY TO
GET TOO SPECIFIC...BUT NORTHWARD SURGING WARM FRONT ITSELF IS
DISCONCERTING...AS IS POTENTIALLY BREAKING INTO THE WARM SECTOR FOR
AT LEAST PARTS OF THE AREA. MUCH...OF COURSE...WILL DEPEND ON
UPSTREAM CONVECTIVE EVOLUTION...BUT WOULD NOT BE AT ALL SURPRISED TO
SEE OUR FIRST SEVERE THUNDERSTORM EVENT OF THE SEASON (AND ENDING
ONE OF THE LATEST STARTS TO SUCH IN OUR RECENT HISTORY). OVERNIGHT
ISSUED SPC SEVERE GRAPHICS CONCUR...BRINGING TUESDAY INTO WEDNESDAY
SLIGHT RISK CATEGORY UP TO ABOUT M-32. DEFINITELY SOMETHING TO
MONITOR IN THE COMING DAYS...BUT WILL DEFER INTRODUCING THIS THREAT
IN THE LATEST RENDITION OF THE HAZARDOUS WEATHER OUTLOOK UNTIL
BETTER CONFIDENCE IS REALIZED. FORECASTING TEMPERATURES EVEN A MUCH
LOWER CONFIDENCE ENDEAVOR THAN ALL THE ABOVE. WILL SIMPLY USE A
CONSENSUS APPROACH FOR NOW...AND WILL HONESTLY STATE FORECAST WILL
LIKELY IN NO WAY MIMIC REALITY.

MID LEVEL LOW OPENS UP AS IT PASSES OVERHEAD LATER WEDNESDAY AND
WEDNESDAY NIGHT (TIMING SUBJECT TO CHANGE...OF COURSE)...EVENTUALLY
BECOMING ABSORBED IN DEEPENING EASTERN TROUGH TO END THE WEEK. RAINS
LOOK TO CONTINUE WEDNESDAY NIGHT...PERHAPS LINGERING INTO THURSDAY.
START OF THE HOLIDAY WEEKEND CONTINUES TO LOOK DRY AND SEASONABLY
COOL AS STRONG CANADIAN HIGH PRESSURE BUILDS SOUTH FRIDAY AND
SATURDAY BETWEEN EASTERN TROUGHING AND HIGH PLAIN RIDGING. HIGHS
TEMPERATURES NOT EXCEPTIONALLY COOL...BUT STILL A FEW DEGREES BELOW
NORMAL...WITH READINGS FRIDAY IN THE UPPER 50S AND LOWER
60S....WARMING SLIGHTLY INTO THE 60S FOR SATURDAY. BIGGER CONCERN
REMAINS FOR SOME RATHER CHILLY OVERNIGHT LOWS. COULD SEE SOME
READINGS DIP INTO THE MIDDLE AND UPPER 30S AS QUICKLY AS THURSDAY
NIGHT...DRIVEN SIMPLY BY SHOT OF CAA ON NORTHEAST TO NORTH WINDS.
PER PATTERN RECOGNITION...FRIDAY NIGHT CONTINUES TO LOOK DOWNRIGHT
CHILLY WITH COOL HIGH PRESSURE AND ATTENDANT DRY AIR CENTERED
DIRECTLY OVERHEAD. DESPITE BEING AT LEAST PARTIALLY CLIMATOLOGICALLY
INFLUENCED AT THIS TIME FRAME...LATEST ECMWF MOS PROGS CONTINUE TO
LOOK RATHER DISCONCERTING...FEATURING WIDESPREAD LOWER AND MIDDLE 30
DEGREE READINGS BY EARLY SATURDAY MORNING (GFS MEX PROGS ALSO
TRENDING COOLER...ALTHOUGH NOT YET TO THIS EXTREME). WILL START THE
PROCESS OF TRENDING COOLER THROUGH THIS PERIOD AND INTRODUCE THE
MENTION OF THIS FROST POTENTIAL IN THE HAZARDOUS WEATHER OUTLOOK FOR
NORTHERN LOWER MICHIGAN (FROST/FREEZE SEASON DOESN`T KICK OFF FOR
UPPER MICHIGAN UNTIL MEMORIAL DAY). JUST TOOK A QUICK PERUSAL OF
LATEST 12Z ECMWF...WHICH HAS TRENDED MUCH STRONGER WITH CAA THURSDAY
NIGHT THROUGH SUNDAY. IF THIS IS REALIZED...HIGHS FRIDAY WILL LIKELY
BE STUCK IN THE 50S...WITH OVERNIGHT LOWS RANGING FROM THE MID AND
UPPER 30S THURSDAY NIGHT AND AGAIN SATURDAY NIGHT...WITH WIDESPREAD
UPPER 20 TO MID 30 DEGREE READINGS FRIDAY NIGHT. QUESTIONS ABOUND BY
SUNDAY...WITH SOME POTENTIAL FOR DEVELOPING WAA TO KICK OFF AT LEAST
THE THREAT FOR A FEW SHOWERS. IN NO HURRY TO INTRODUCE THIS JUST YET
GIVEN INHERENT TIMING CONCERNS.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 742 PM EDT SUN MAY 19 2013

MOSTLY VFR...THOUGH THE CHANCE FOR BRIEF RESTRICTIONS DUE TO
SHRA/TSRA WILL INCREASE THRU THE FORECAST. ALSO A SLIGHT CHANCE
FOR FOG LATE TONIGHT.

IN ADVANCE OF A COMPLEX LOW PRESSURE SYSTEM IN THE PLAINS...WARMER
AND MORE HUMID AIR CONTINUES TO GRADUALLY WORK NORTHWARD INTO MI.
THE CHANCE FOR THIS AIRMASS TO PRODUCE SHRA/TSRA WILL
INCREASE...AND ESPECIALLY ON MONDAY AFTERNOON. HAVE INTRODUCED
VCTS INTO ALL TAFS FOR A FEW HOURS. THERE ARE SMALLER CHANCE FOR
PRECIP EVEN BEFORE THAT...BUT THESE CHANCES ARE NOT HIGH ENOUGH TO
WARRANT MENTION IN THE TAFS AT THIS TIME.

SOME POTENTIAL FOR VSBYS RESTRICTIONS IN BR LATE TONIGHT...AND 06Z
TAFS COULD SEE SOME TEMPO GROUPS INTRODUCED TO ACCOUNT FOR THIS.

LIGHT WINDS TONIGHT...BECOMING SOMEWHAT BREEZY FROM THE EAST AT
APN/PLN MONDAY...LESS BLUSTERY FROM THE SOUTH TVC/MBL.

&&

.MARINE...
ISSUED AT 340 PM EDT SUN MAY 19 2013

A WEAK GRADIENT WILL CONTINUE TO PROVIDE LIGHT WINDS ACROSS THE
WATERS TODAY THRU TONIGHT...BUT WITH EASTERLY FLOW GRADUALLY
STRENGTHENING LATE TONIGHT THROUGH MIDWEEK...NORTH OF A WARM FRONT
STALLING NEARBY. SMALL CRAFT ADVISORIES MAY EVENTUALLY BE
NEEDED...ESPECIALLY LATER MONDAY THROUGH WEDNESDAY...AND
PARTICULARLY IN AND AROUND THE STRAITS WHERE EASTERLY FLOW WILL BE
CHANNELED. HIGH PRESSURE IS EXPECTED TO SLOWLY WORK BACK INTO THE
REGION LATE IN THE WORK WEEK AND TOWARD NEXT WEEKEND...WITH A RETURN
TO LIGHT WINDS.


&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...NONE.
LM...NONE.
LS...NONE.

&&

$$

UPDATE...JZ
SYNOPSIS...KB
SHORT TERM...JK
LONG TERM...MB
AVIATION...JZ
MARINE...JK