000
FXUS63 KAPX 142313
AFDAPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
713 PM EDT TUE MAY 14 2013

.SYNOPSIS...
ISSUED AT 355 PM EDT TUE MAY 14 2013

A WARM FRONT MOVING THROUGH THE AREA WILL GENERATE A CHANCE OF
SHOWERS AND THUNDERSTORMS TONIGHT. EARLY ON WEDNESDAY...THE
TRAILING COOL FRONT WILL MOVE THROUGH...SCOURING MOISTURE OUT OF THE
AREA. IT IS ONLY A COOL FRONT IN THE TECHNICAL SENSE...AS COOL AIR
IT WILL NOT BRING. ON THE CONTRARY...MUCH DRIER AIR AND CLEARER
SKIES WILL FOLLOW...WHICH WILL ALLOW TEMPERATURES TO MODERATE TO
THEIR WARMEST READINGS SINCE LAST THURSDAY. SEASONABLY WARM AND
DRIER CONDITIONS WILL LAST THROUGH THE END OF THE WORK WEEK.

&&

.UPDATE...
ISSUED AT 713 PM EDT TUE MAY 14 2013

POTENT BUT MOISTURE-STARVED WAVE SLIDING THRU OUR SW CWA HAS
KICKED OFF SOME SCATTERED LIGHT SHOWERS...BUT THESE SHOWERS HAVE
YET TO SHOW EVIDENCE OF ACTUALLY REACHING THE GROUND. THE REST OF
OUR CWA REMAINS DRY THIS EVENING...WITH JUST SOME SCT/BKN MID/HIGH
CLOUD OVERHEAD. FURTHER UPSTREAM ALONG THE APPROACHING COLD
FRONT...A WELL-DEFINED LINE OF SHOWERS AND STORMS HAS DEVELOPED
ALONG THE FRONT FROM SW WISCONSIN THRU NRN IOWA INTO CENTRAL
NEBRASKA. THIS LINE IS ALSO FEEDING OFF A STRONG 850 MB THETA E
RIDGE AND INSTABILITY AXIS AS THE NOSE OF A 45 KT 850 MB JET MAX.
ALL OF THESE FEATURES WILL LEAN INTO OUR CWA OVERNIGHT...RESULTING
IN INCREASING CHANCES OF SHOWERS AND STORMS. CURRENT FORECAST IS
ON TARGET SO FAR...BUT WILL CERTAINLY KEEP A CLOSE EYE ON THE ERN
EDGE OF THAT LINE OF STORMS AS WE HEAD THRU THE EVENING HOURS FOR
ANY SIGNS OF REACHING OUR SW COUNTIES EARLIER.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 355 PM EDT TUE MAY 14 2013

CURRENTLY, THE DYING DEBRIS OF THE CONVECTION OVER NORTH DAKOTA THIS
MORNING IS NOW ISOLATED TO SCATTERED SHOWERS IN NORTHERN WISCONSIN
AND W UPPER. WITH THE LOW DEW POINTS (MID TO UPPER 30S) WITH THIS,
AM BEGINNING TO DOUBT THAT MUCH WILL GET HERE. LOOKING UPSTREAM WITH
THE SFC LOW AND OCCLUDED FRONT, THE THUNDER IS ASSOCIATED WITH THIS
FEATURE CURRENTLY, WHILE SOUTH OF THE LOW IN THE "COLD" AIR
TEMPERATURES ARE RUNNING IN THE 70S WITH MID 30 TO MID 40S
DEW POINTS.

TONIGHT...THE MODELS THE LAST COUPLE OF DAYS HAVE WANTED TO
RAM THE WARM FRONT THROUGH HERE. HOWEVER, THE TRENDS OF THE WARM
FRONT AND THE MODELS TODAY SHOW THE FRONT STAYING SOUTH OF THE HERE
WITH THE BAROCLINIC ZONE STALLING OVER N LOWER. EVENTUALLY, THE
TRIPLE POINT WITH THE COLD/OCCLUDED/WARM FRONTS MOVES INTO N LOWER
AROUND 06Z. SO WILL SEE AN UPTICK IN SHOWERS, WITH SOME THUNDER. THE
MID LEVEL LAPSE RATES (700-500 MB LAYER) ARE BETWEEN 6.5 AND 7.5
C/KM IN N LOWER SO WILL LEAVE THE CHANCE OF THUNDER IN THE FORECAST
AFTER 03Z AS THIS SYSTEM MOVES INTO THE REGION. THE 850 MB WINDS DO
PICK UP, BUT THERE IS NO GOOD LOW LEVEL JET INTO THE WARM SECTOR TO
REALLY GET GOOD, STRONGER CONVECTION GOING, SO WILL CONTINUE THAT IF
A THUNDERSTORM IS ABLE TO BUST THE CAP. SHOWALTER INDICES SHOW
ABOUT -2C SOUTH OF M-32, SO THE STRONGER STORMS THAT CAN GET GOING
WILL BE SOUTH OF THERE, AND MORE LIKELY SOUTH OF M-55, CLOSER TO THE
700-500 MB LAPSE RATE MAXIMA IS. THE THUNDERSTORMS LOOK TO BE OUT OF
HERE BY 12Z.

WEDNESDAY...THE COLD FRONT IS NOT MUCH OF COLD FRONT, BUT RATHER A
DRY LINE WITH A WIND SHIFT. CONSIDERING THAT NCEP HAS BEEN WARNING
OF THE SFC MOISTURE FIELDS, TOOK THE NOVEL APPROACH TO RUN THE
HYSPLIT TRAJECTORY MODELS BACKWARD TO SEE WHERE THE AIR FOR
WEDNESDAY WOULD BE ORIGINATING FROM. AS IT TURNS OUT THE NAM AND GFS
ARE SHOWING THAT THE AIR IS COMING OUT OF THE CANADIAN PRAIRIES WEST
OF LAKE WINNIPEG. DEW POINTS THERE ARE RUNNING IN THE LOWER TO MID
30S. WHICH IS WHAT HAS BEEN EXPECTED THE LAST COUPLE OF DAYS NOW.
WITH THE TEMPERATURES IN THE MID 70S EXPECTED AS WELL, WE WILL HAVE
ELEVATED FIRE DANGER WORDING IN SOME OF OUR PRODUCTS. THE GRADIENT
ON THE BACK SIDE OF THE COLD FRONT AND SFC LOW WON`T GET QUITE TIGHT
ENOUGH TO GET HIGHER WINDS, AND LOOKS LIKE ON THE GFS AND ECMWF TO
RELAX BY THE LATE AFTERNOON, SO WE WON`T GET TO 15 MPH AT THE 20FT
LEVEL SUSTAINED FOR RED FLAG CONDITIONS. THERE WILL BE SOME GUSTS TO
15-20 MPH, HOWEVER.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 355 PM EDT TUE MAY 14 2013

RECENT TRENDS: TEMPERATURES...WARM START TO MAY HAS BEEN OFFSET BY
THE CHILL OVER THE LAST FOUR DAYS...TEMPERATURE ANOMALIES 1-2C BELOW
NORMAL LAST 7 DAYS BUT STILL ABOVE NORMAL FOR MAY AS A WHOLE (1-2C
ABOVE).  WARM NORTHEAST AND ACROSS THE WESTERN STATES SO FAR THIS
MONTH...COLD DOWN THE MIDDLE AND INTO THE SOUTHEAST.  PRECIPITATION/
HYDROLOGY...THE RETURN OF COOLER WEATHER ALSO BROUGHT A RETURN TO
PRECIPITATION AFTER A DRY FIRST WEEK OF MAY.  PRECIP LAST 7 DAYS
150-200 PERCENT NORMAL ACROSS NORTHEAST LOWER...PRECIP FOR MAY ABOVE
NORMAL EAST OF M-33 CORRIDOR...BELOW NORMAL ELSEWHERE ESPECIALLY
ACROSS EASTERN UPPER (PORTIONS MACKINAC COUNTY BELOW 50 PERCENT
NORMAL).  30 DAY STANDARDIZED PRECIPITATION INDEX NEAR-ABOVE NORMAL
ACROSS NORTHERN MICHIGAN.  MEAN STREAMFLOW ON AREA RIVERS RUNNING
NEAR TO ABOVE NORMAL.  GREAT LAKES...WATER TEMPERATURES LAKE
SUPERIOR 2-3C...NORTHERN LAKE MICHIGAN 3-4C (5C STRAITS)...NORTHERN
LAKE HURON 3C (WARMER SAGINAW BAY).  LATEST LAKE MICHIGAN/HURON
WATER LEVEL PROJECTION IS 1.5-2 FEET BELOW AVERAGE THROUGH
SUMMER.

LARGE SCALE PATTERN/FORECAST: FIVE WAVE HEMISPHERIC PATTERN WITH
GENERALLY ZONAL FLOW ACROSS MUCH OF THE CONUS WITH TROUGHING PUSHING
OFF THE EAST COAST.  RECENT STRONG BLOCKING ACROSS THE PACIFIC HAS
WANED (STRONG -WPO/-EPO HAVE FLIPPED TOWARD POSITIVE).  SHORT WAVE
ENERGY CROSSING THE CANADIAN PRAIRIE PROVINCES TODAY WILL RESULT IN
SOME TEMPERATURE SWINGS THROUGH MIDWEEK...WITH A TREND TOWARDS
WARMING INTO THE WEEKEND AND EARLY NEXT WEEK PERHAPS PUNCTUATED BY
STORMY WEATHER TOWARD THE END OF THE EXTENDED FORECAST PERIOD.

WEDNESDAY NIGHT THROUGH FRIDAY: COLD ADVECTION IN THE WAKE OF
WEDNESDAY`S COLD FRONT PASSAGE TO START THE MID RANGE OF THIS
FORECAST CYCLE...NORTHERN MICHIGAN JUST ON THE FRINGES OF SURFACE
LOW OVER QUEBEC WEDNESDAY NIGHT/THURSDAY.  WEAK AREA OF HIGH
PRESSURE THEN BUILDS IN FOR THURSDAY NIGHT AND FRIDAY.  NOT MUCH IN
THE WAY OF FORECAST CONCERNS IN THIS PERIOD WITH THE EXCEPTION OF
FIRE WEATHER.  SEASONABLE TEMPERATURES EXPECTED WEDNESDAY NIGHT/
THURSDAY GIVE OR TAKE A COUPLE DEGREES.  WILL LIKELY APPROACH RED
FLAG CRITERIA ACROSS INTERIOR NORTHERN LOWER THURSDAY AFTERNOON AS
RELATIVE HUMIDITY VALUES EXPECTED TO MIX BELOW 25 PERCENT WITH WINDS
GUSTING 15-20 MPH.  TEMPERATURES WILL PROBABLY FALL A BIT SHORT OF
THE 75 DEGREE CRITERIA.

WEAK LOW/MID LEVEL RIDGING ACROSS THE UPPER LAKES FOR FRIDAY...SOME
UNSETTLED WEATHER UPSTREAM RELATED TO WARM ADVECTION AND A VORTICITY
CENTER MOVING THROUGH THE MID MISSISSIPPI VALLEY.  WILL PROBABLY SEE
SOME HIGH CLOUDS ASSOCIATED WITH THAT DRIFT ACROSS.  TEMPERATURES
AGAIN SHOULD BE NEAR NORMAL...WILL BE LESS WIND THAN THURSDAY
AFTERNOON SO FIRE WEATHER PARAMETERS WILL PROBABLY BE A LITTLE
BETTER THOUGH RELATIVE HUMIDITY VALUES AGAIN LIKELY TO DROP BELOW 30
PERCENT ACROSS THE INTERIOR.

EXTENDED FORECAST (SATURDAY THROUGH TUESDAY): WARM ADVECTION GETS
UNDERWAY THIS WEEKEND WITH SHORT WAVE RIDGING BUILDING INTO THE
UPPER LAKES WHILE BROADER AREA OF HEIGHT FALLS CROSSES THE WESTERN
MOUNTAINS/GREAT BASIN AND PRESSURES FALL ACROSS THE PLAINS.
EVOLUTION OF WESTERN TROUGHING IN QUESTION AS IT EMERGES INTO THE
CENTRAL U.S. BY SUNDAY.  WILL PROBABLY HAVE A WARM FRONT SETTING UP
SOUTH OF THE STATE THIS WEEKEND AND ADVANCING NORTHWARD WITH
TIME...EAST/SOUTHEAST BOUNDARY LAYER FLOW EMANATING FROM HIGH
PRESSURE OVER EASTERN CANADA ALSO ADDS A LAYER OF UNCERTAINTY WITH
RESPECT TO PRECIP POTENTIAL.  LONGER RANGE GUIDANCE IS TRENDING
DRIER (INCLUDING LATE ARRIVING 14/12Z ECMWF)...SO WILL ALSO TREND
THE FORECAST DRIER FOR THE WEEKEND AND KEEP PRECIPITATION CHANCES
STARTING SUNDAY NIGHT AND INTO THE START OF THE WORK WEEK.  NEW
ECMWF IS ALSO QUICK TO COOL THINGS DOWN TO START THE NEW TUESDAY
FORECAST...BUT NOT INTERESTED IN GOING THAT DIRECTION YET. REFERENCE
IS TOWARD A SLOWER SYSTEM TRACK AND KEEPING THE GREAT LAKES ON THE
MILD SIDE OF THINGS THROUGH TUESDAY.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 713 PM EDT TUE MAY 14 2013

VFR CONDITIONS ARE EXPECTED THRU WEDNESDAY EVENING DESPITE SMALL
CHANCES OF SHOWERS AND STORMS ALONG AND AHEAD OF A COLD FRONT
SCHEDULED TO PASS THRU NRN LWR MICHIGAN OVERNIGHT. A FEW SHOWERS
WILL IMPACT THE MBL AREA THIS EVENING...AND WILL HANDLE WITH VCSH
FOR NOW. ADDITIONAL SCATTERED SHOWERS AND STORMS WILL SLIDE THRU
FAR NRN AND NE LWR MICHIGAN (PLN AND APN) LATE TONIGHT WILL THE
ACTUAL PASSAGE OF THE FRONT. CAA WILL KICK IN EARLY WEDNESDAY
MORNING...AS DRIER AIR FILTERS INTO THE REGION AS WELL. SE WINDS
AOB 10 KTS TONIGHT WILL SHIFT TO THE NW AND STRENGTHEN TO 15 TO 25
KTS ON WEDNESDAY.

&&

.MARINE...
ISSUED AT 355 PM EDT TUE MAY 14 2013

WINDS DON`T LOOK LIKE THEY WILL REACH SMALL CRAFT CRITERIA OVER THE
NEXT 48 HOURS AS THE SFC LOW AND FRONT DROP INTO THE REGION BRIEFLY
TIGHTENING THE GRADIENT. HOWEVER, THE HEART OF THE TROUGH MOVES
THROUGH RELAXING THE GRADIENT AND SWITCHING THE DIRECTION. THE
GRADIENT THEN TIGHTENS BRIEFLY, HOWEVER, JUST BEFORE SMALL CRAFT
CONDITIONS ARE REALIZED, THE GRADIENT RELAXES BY WEDNESDAY
AFTERNOON. WEDNESDAY NIGHT INTO THURSDAY, THE WINDS WILL CONTINUE TO
DIMINISH AS THE HIGH BUILDS INTO THE REGION.


&&

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

&&

$$

UPDATE...MR
SYNOPSIS...KAB
SHORT TERM...JSL
LONG TERM...JPB
AVIATION...MR
MARINE...JSL