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000
FXUS63 KAPX 181927
AFDAPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
327 PM EDT SAT MAY 18 2013

.SYNOPSIS...
ISSUED AT 316 PM EDT SAT MAY 18 2013

HIGH PRESSURE WILL PROVIDE A LITTLE MORE SUNSHINE...THUS A BIT
WARMER TEMPERATURES FOR SUNDAY. HOWEVER...A STORM SYSTEM DEVELOPING
OVER THE ROCKIES WILL BECOME BETTER ORGANIZED OVER THE
PLAINS...BEFORE MOVING INTO THE GREAT LAKES TO START THE WORK WEEK.
THIS APPROACHING SYSTEM WILL GENERATE THUNDERSTORMS AND MILD
TEMPERATURES...OVER NORTHERN MICHIGAN THROUGH MID WEEK.

&&

.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 316 PM EDT SAT MAY 18 2013

ELEVATED WARM FRONT/WARM AIR ADVECTION WING CONTINUES TO LIFT THRU
THE AREA TONIGHT WITH LINGERING MID LEVEL FGEN AND ADIABATIC OMEGA
POSSIBLY PRODUCING A FEW SPRINKLES/LIGHT SHOWER TIP OF THE MITT INTO
EASTERN UPPER.  SKY CONDITIONS RANGING FROM PARTLY CLOUDY SOUTH TO
MOSTLY CLOUDY NORTH.  A MILD NIGHT WITH LOWS FROM THE MID 40S TO
LOWER 50S.

BY FAR THE BEST DAY OF THE WEEKEND ON SUNDAY WITH 850MB THERMAL
RIDGE OF 13-15C BUILDING INTO THE AREA.  MID LEVEL RIDGING WILL
CONTINUE TO DOMINATE OUR WEATHER PICTURE AS DEEPER TROUGH DIGS INTO
THE NORTHERN PLAINS.  SFC DEWPOINTS WILL CONTINUE TO GRADUALLY CREEP
UP AS THE DAY PROGRESSES.  NAM CONTINUING ITS RECENT BIAS OF TOO WET
LOWER LEVELS...WITH CURRENT FCST DEWPOINTS 3-5 DEGF TOO HIGH BASED
ON LATEST OBSERVATIONS.  QUITE WARM ON SUNDAY...WITH HIGH TEMPS
REACHING THE MIDDLE 70S /EASTERN UPPER/ TO LOWER 80S /PORTIONS OF
NORTHERN LOWER/.  WEAK GRADIENT AND WARM TEMPS LEND ITSELF TO LAKE
BREEZE DEVELOPMENT DURING THE AFTERNOON HOURS AND WILL COOL TEMPS
CLOSER TO THE COASTS TO ACCOUNT FOR THIS.  EVEN WITH SLIGHTLY LOWER
DWPTS THAN THE NAM FCST SOUNDINGS...MODIFIED SOUNDINGS WITH NEAR DRY
ADIABATIC MIXED LAYER YIELD SEVERAL HUNDRED JOULES OF SKINNY CAPE.
INLAND PENETRATING LAKE BREEZE BOUNDARIES...INCREASING SFC DWPTS AND
SOME INSTABILITY SUPPORT ISOLATED SHOWER MENTION FOR INTERIOR AREAS
DURING THE MID/LATE AFTERNOON.

&&

.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 316 PM EDT SAT MAY 18 2013

MID AND UPPER LEVEL PATTERN BECOMING INCREASINGLY BLOCKY WITH
TIME...AT LEAST PARTIALLY DRIVEN BY STRONG NORTH CENTRAL ATLANTIC
CENTERED HIGH PRESSURE RIDGE AXIS. DUAL STRONG SHORTWAVE TROUGHS
DIVING INTO THE PACIFIC NORTHWEST ONLY HELPING THE CAUSE...WITH LEAD
ENERGY EVENTUALLY CARVING OUT A SLOW MOVING UPPER LOW IN THE NATIONS
MIDSECTION EARLY NEXT WORK WEEK...WHILE THE NEXT PIECE DOES THE SAME
ACROSS THE PACIFIC NORTHWEST. SUBSEQUENT CANADIAN PRAIRIE RIDGE
BUILDING BETWEEN THESE FEATURES SETS UP A QUASI-OMEGA BLOCK
SIGNATURE...WITH STRONG ENERGY PROGGED TO DIVE DOWN ITS FRONTSIDE
INTO EAST CENTRAL CANADA ONLY ADDING FURTHER COMPLEXITY TO AN
ALREADY COMPLEX PATTERN. ADD IN A GOOD SUPPLY OF GULF OF MEXICO
MOISTURE AND FGEN DYNAMICS...AND THE PATTERN HAS ALL THE MAKINGS OF
A WET ONE THROUGH AT LEAST THE FIRST HALF OF THIS UPCOMING WEEK.
LATEST WPC 5 AND 7 DAY QUANTITATIVE PRECIPITATION FORECASTS
CONCUR...WITH WIDESPREAD 1 TO 2 INCH AMOUNTS ACROSS OUR AREA...WITH
HEAVIER AMOUNTS TO UPWARDS OF 4 INCHES JUST TO OUR NORTHWEST. AS ONE
CAN IMAGINE GIVEN ABOVE...EXTENDED FORECAST CONCERNS MAINLY CENTER
ON MULTI-PERIOD RAIN SHOWER AND THUNDERSTORM THREATS.

ONE COMPLICATED FORECAST SUNDAY NIGHT INTO MONDAY...WHICH...TO BE
HONEST...DOES NOT SUPPORT A WHOLE LOT OF FORECAST CONFIDENCE.
CENTRAL PLAINS CLOSED LOW BECOMES INCREASINGLY WELL ESTABLISHED...
WITH EXCELLENT FORCED LOW/MID LEVEL CONVERGENCE ZONE SETTING UP
BETWEEN SOUTH FLOW OUT AHEAD OF IT WEAK ENERGY DIVING THROUGH
ONTARIO. STRONG H8 CONVERGENCE AXIS LOOKS TO SLOWLY SAG SOUTH ACROSS
LAKE SUPERIOR SUNDAY NIGHT INTO MONDAY...WITH SURFACE REFLECTION
ESSENTIALLY REMAINING STATIONARY ACROSS THE CLIMATOLOGICALLY FAVORED
TIP OF THE MITT/STRAITS REGION. H8 FRONT LOOKS TO REMAIN VERY
ACTIVE...FOCUSING MUCH OF THE RAIN OFF TO OUR NORTH THROUGH SUNDAY
NIGHT...PERHAPS INTO THE FIRST PART OF MONDAY (HELPED IN PART BY MID
LEVEL RIDGING REMAINING OVERHEAD). CONDITIONS BECOME MUCH MORE
INTERESTING HEADING INTO MONDAY AFTERNOON AND NIGHT AS ENERGY
ROTATING AROUND UPPER LEVEL LOW INTERACTS WITH AN INCREASINGLY
IMPRESSIVE OVERHEAD MOISTURE PLUME AS PWAT VALUES APPROACH AN INCH
AND A HALF. WHILE MODEL DEPICTED SURFACE DEWPOINTS IN THE UPPER
60S/LOWER 70S SEEM AGGRESSIVE...JUXTAPOSITION OF DECENT MOISTURE AND
MID LEVEL SUPPORT SHOULD BE ENOUGH TO KICK OFF ROUNDS OF SHOWERS AND
STORMS...SOME OF WHICH MAY BRING LOCALLY HEAVY RAINFALL. WHILE
SEVERE THREAT NOT COMPLETELY ZERO...BETTER POTENTIAL SHOULD REMAIN
TO OUR SOUTHWEST WITHIN CORRIDOR OF MUCH MORE IMPRESSIVE DEEP LAYER
SHEAR AND BETTER LOW LEVEL INSTABILITY. LATEST DAY 3 SPC SEVERE
GRAPHICS DOES BRING THE SLIGHT RISK RIGHT TO OUR DOORSTEP OVER
SOUTHWEST MICHIGAN. NO DOUBT WORTH KEEPING AN EYE ON THE NEXT FEW
DAYS AS UPSTREAM CONVECTIVE TRENDS WILL LIKELY PLAY HAVOC WITH EXACT
THERMODYNAMIC AND KINEMATIC DETAILS. POTENTIALLY ANOTHER WARM ONE
MONDAY...ESPECIALLY SOUTH OF THE BRIDGE. THERMAL PROGS EASILY
SUPPORT HIGHS BACK INTO THE LOWER 80S...ALTHOUGH CLOUD AND
CONVECTIVE TRENDS MAY PREVENT FULL WARMING FROM BEING REALIZED.

MID-WEEK WEATHER DEPENDENT ON INTERACTION (OR LACK THEREOF) BETWEEN
APPROACHING MID LEVEL LOW AND STRONGER ENERGY DIVING SOUTH OUT OF
CANADA. THE FORMER CONTINUES TO SUPPLY PLENTY OF MOISTURE AND
DYNAMICS...WHILE THE LATTER ATTEMPTS TO DRIVE BEST FGEN/BAROCLINIC
ZONE FURTHER SOUTH WITH TIME. DEEP LAYER CONVERGENCE AND MOISTURE
SUPPORTS PLENTY OF RAIN POTENTIAL...WITH PLACEMENT OF THE HEAVIEST
AND STEADIEST RAINFALL TIED TO ABOVE INTERACTION. 00Z ECMWF/GEM
OFFER A RATHER WET SCENARIO...KEEPING CORRIDOR OF DEEP LAYER
CONVERGENCE OVERHEAD RIGHT THROUGH THURSDAY. GFS A TOUCH MORE
AGGRESSIVE DRIVING THIS CORRIDOR SOUTH...ALTHOUGH IT TOO SUGGESTS
LINGERING RAINS INTO THURSDAY (JUST NOT AS HEAVY). HARD TO GET A
FEEL FOR WHICH IS MORE CORRECT...WITH THE END RESULT LIKELY A MIDDLE
GROUND BETWEEN THE TWO. INHERITED FORECAST KEEPS RAINS LINGERING
THROUGH THURSDAY...AS WILL THIS FORECAST. SEVERE THREAT SHOULD ONLY
SAG SOUTH WITH TIME AS LOW LEVEL BAROCLINIC ZONE DOES THE SAME. THAT
SAID...PROXIMITY OF IT AND SOME EVIDENCE FOR IT TO RETURN BRIEFLY
NORTH LATER WEDNESDAY...AS MAIN WESTERN ENERGY APPROACHES...
DEFINITELY RAISES SOME CONCERN.

START OF MEMORIAL DAY WEEKEND LOOKING COOL AND DRY AS CANADIAN HIGH
PRESSURE BUILDS OVERHEAD. HIGHS FRIDAY AND SATURDAY LOOK TO ONLY
REACH INTO 60S (UPPER 50S ACROSS EASTERN UPPER?)...WHICH WOULD BE AT
LEAST A FEW DEGREES BELOW NORMAL. PATTERN RECOGNITION SUPPORTS THE
POTENTIAL FOR SOME RATHER CHILLY OVERNIGHT READINGS THURSDAY THROUGH
SATURDAY. SOMEWHAT DISCONCERTING TO SEE LATEST CLIMO INFLUENCED
ECMWF MOS SHOWING COLDER LOCATIONS DIPPING INTO THE MIDDLE AND UPPER
30S EARLY FRIDAY MORNING...AND WIDESPREAD LOWER AND MIDDLE 30 DEGREE
READINGS SATURDAY MORNING. OTHER GUIDANCE NOT QUITE AS COLD...BUT
DEFINITELY SOMETHING TO MONITOR.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1244 PM EDT SAT MAY 18 2013

VFR CONDITIONS EXPECTED THROUGHOUT THE PERIOD.  WARM FRONT WILL
MOVE NORTH OF THE AREA THROUGH TONIGHT WITH MID CLOUDS AND
A FEW SPRINKLES.  SCATTERED DIURNAL CU FIELDS ON SUNDAY WITH BASES
FROM 5-6K.  LIGHT WINDS THROUGHOUT...WITH LAKE BREEZE DEVELOPMENT
CLOSER TO THE COASTS ON SUNDAY.


&&

.MARINE...
ISSUED AT 316 PM EDT SAT MAY 18 2013

GRADIENT WILL REMAIN RELATIVELY WEAK OVER THE NEXT FEW DAYS AS HIGH
PRESSURE SLOWLY DEPARTS TO THE EAST. AS LOW PRESSURE DRAWS CLOSER
TO THE AREA TUESDAY/WEDNESDAY...WINDS WILL INCREASE AND SMALL
CRAFT CONDITIONS ARE POSSIBLE.

&&

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

&&

$$

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