000
FXUS63 KGRR 151411
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1011 AM EDT WED MAY 15 2013

LATEST UPDATE...
MARINE

.SYNOPSIS...
ISSUED AT 339 AM EDT WED MAY 15 2013

A COLD FRONT WILL SLIP THROUGH THE AREA TODAY. THERE IS A SMALL
RESIDUAL CHANCE OF A SHOWER OR STORM DOWN SOUTH EARLY THIS MORNING.
THIS THREAT WILL QUICKLY END JUST AFTER DAYBREAK.

HIGH PRESSURE WILL BUILD IN THEN FOR THURSDAY AND FRIDAY. THIS
SHOULD ALLOW FOR DRY AND MILD WEATHER FOR THE AREA. THIS COULD
CONTINUE INTO SATURDAY. THE THREAT FOR RAIN WILL GRADUALLY INCREASE
BEGINNING ON SUNDAY AND INTO MONDAY AS MILD TEMPERATURES REMAIN
LIKELY.

&&

.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 339 AM EDT WED MAY 15 2013

THE ONLY REAL FCST CHALLENGE IS DEALING WITH PCPN CHCS EARLY THIS
MORNING AS THE FRONTAL SYSTEM MOVES THROUGH THE AREA.

A FEW WEAK SHOWERS AND STORMS MOVED THROUGH THE CWFA EARLIER IN THE
VICINITY OF THE WARM FRONT AND AT THE LEADING EDGE OF THE STRONGER
MOISTURE TRANSPORT/WARM AIR ADVECTION ALOFT ASSOCIATED WITH THE LLJ.
THE PCPN WITH THIS SYSTEM HAS BEEN UNDERPERFORMING THUS FAR...AND
THE WINDOW OF OPPORTUNITY IS CLOSING ON THE PCPN CHCS. WE BELIEVE
THAT THE FLOW ALOFT BEING FROM THE W/SW IS NOT CONDUCIVE TO BRINGING
IN RICH MOISTURE WHICH ACCOUNTS FOR THE WEAK PCPN TRENDS.

EVEN IF THE LLJ/MOISTURE TRANSPORT WAS PRODUCING MORE THIS
MORNING...THE CORE OF IT WILL BE QUICKLY SHIFTING EAST THIS MORNING.
IT SHOULD BE EAST OF LAKE HURON BY 12Z. THIS MEANS THAT THE CHCS
WILL ONLY BE DROPPING FROM HERE ON OUT. THE SKIES ARE CLEARING OUT
FOR MOST OF THE CWFA SO THE RAIN POTENTIAL LOOKS PRETTY BLEAK FOR
TODAY. BY THE TIME ANY INSTABILITY WOULD HAVE A CHANCE TO BUILD
AHEAD OF THE FRONT...IT WILL BE SOUTH OF THE AREA. THE AIR BEHIND
THE COLD FRONT IS NOT ALL THAT COLD...IT IS JUST NOT GOING TO BE IN
THE 90S AND 100S LIKE WAS THE CASE WELL WEST OF THE AREA WITH H850
TEMPS AROUND OR ABOVE 20C. WE SHOULD SEE TEMPS SIMILAR TO YESTERDAY
WITH HIGHS IN THE 70S.

HIGH PRESSURE WILL HOLD IN CONTROL OF THE AREA GENERALLY THROUGH AT
LEAST FRI. WE WILL SE AN UPPER RIDGE CURRENTLY ACROSS THE PACIFIC NW
ONLY SLOWLY SHIFT EAST THROUGH THE END OF THE WEEK. H850 TEMPS WILL
REMAIN UP IN THE LOWER TEENS AND A FAIR AMOUNT OF SUNSHINE CAN BE
EXPECTED.

THE ONLY POTENTIAL FLY IN THE OINTMENT WILL BE A SHORT WAVE THAT IS
FORECAST TO TRY TO RIDE OVER THE UPPER RIDGE AROUND FRI. THIS WAVE
WILL TRY TO INTERACT WITH THE NEARLY STALLED OUT FRONT TO OUR SOUTH
AND BRING IT BACK NORTH. WE WILL HAVE A SFC RIDGE TO OUR NORTH WHICH
WILL PUMP DRIER AIR IN FROM THE E/NE. WE BELIEVE THAT THIS SHOULD
DRY UP MOST PCPN THAT TRIES TO MOVE IN  THROUGH FRI.

.LONG TERM...(FRIDAY NIGHT THROUGH TUESDAY)
ISSUED AT 339 AM EDT WED MAY 15 2013

AGREE WITH PREVIOUS FORECASTER THAT THE WEEKEND LOOKS DRIER THAN
YESTERDAY/S MODEL RUNS AND THE 00Z MODELS CONTINUE THAT TREND. THE
UPPER RIDGING CONTINUES TO LOOK FAIRLY STRONG...IN BOTH THE GFS AND
THE ECMWF. THE RIDGE ACTUALLY BUILDS OVER THE GREAT LAKES FROM
FRIDAY NIGHT THROUGH SUNDAY. MAINTAINED SMALL CHANCES FOR RAIN
SHOWERS FRIDAY NIGHT AS A WEAK WAVE SKIRTS BY THE SOUTHERN GREAT
LAKES. CHANCES ARE SMALL AND NOT EXPECTING MUCH. DECIDED TO GO DRY
FROM SATURDAY THROUGH SUNDAY AS THE RIDGE IS DIRECTLY OVERHEAD WITH
LITTLE IN THE WAY OF FORCING.

CHANCES FOR SHOWERS AND STORMS INCREASE FROM SUNDAY NIGHT INTO EARLY
NEXT WEEK...AS THE UPPER RIDGE NUDGES EAST. AN UPPER LOW IS FORECAST
TO BE SLIDE INTO THE VICINITY OF SOUTHERN MINNESOTA...WHICH WILL
PLACE THE GREAT LAKES IN SOUTHWEST UPPER FLOW. HAVE SHOWERS AND
STORMS IN THE FORECAST FROM SUNDAY NIGHT THROUGH TUESDAY. ECMWF HAS
AN 850MB LLJ OVER THE AREA DURING THE SUNDAY NIGHT THROUGH TUESDAY
TIME FRAME WHICH SHOULD PROVIDE A FORCING MECHANISM.

HIGHS WILL CONTINUE TO BE ABOVE NORMAL THROUGH THE PERIOD WITH HIGHS
IN THE UPPER 70S TO LOWER 80S MUCH OF THE TIME.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 716 AM EDT WED MAY 15 2013

VFR CONDITIONS ARE EXPECTED THE NEXT 24 HOURS. THE ONLY CLOUD
COVER ANTICIPATED IS SOME SCT-BKN MID AND HIGH CLOUDS AT TIMES.
WEST TO NORTHWEST WINDS OF 10-23 KNOTS ARE EXPECTED TODAY. WINDS
WILL SUBSIDE QUICKLY THIS EVENING...BECOMING LIGHT AND VARIABLE
AFTER SUNSET.


&&

.MARINE...
ISSUED AT 1010 AM EDT WED MAY 15 2013

LOOKING AT BOTH THE HOLLAND AND MUSKEGON BUOY DATA HOLLAND DID
HAVE WAVES TO 5 FEET AND WIND GUSTS TO 28 KNOTS PRIOR TO MIDNIGHT.
MUSKEGON HAD WAVES TO JUST BELOW 4 FEET AND WIND GUSTS TO 27 KNOTS
AROUND 10 PM... BOTH SITES HAVE WINDS GUSTING UNDER 15 KNOTS AND
SIGNIFICANT WAVE HEIGHTS UNDER 3 FEET. SINCE THE SURFACE HIGH IS
BUILDING IN WINDS SHOULD NOT INCREASE SIGNIFICANTLY OVER THE WATER
SO I ALLOWED THE SMALL CRAFT ADVISORY TO EXPIRE.



&&

.FIRE WEATHER...
ISSUED AT 339 AM EDT WED MAY 15 2013

WE WILL SEE AN ELEVATED FIRE DANGER AT LEAST THE NEXT COUPLE OF DAYS
IF NOT INTO FRIDAY AND SATURDAY. THE COLD FRONT PASSING SOUTH WILL
ALLOW DRIER AIR TO MOVE IN TODAY ALONG WITH MIXING DRIER AIR DOWN.
WE WILL APPROACH THE 25 PCT RH AND 75 DEGREE RFW CRITERIA. WINDS
WILL BE ON THE DECREASE THROUGH THE DAY...SO THE BEST CONFIDENCE
SCENARIO IS THAT WE WILL COME UP JUST SHORT OF CRITERIA.

TEMPS WILL BE SIMILAR ON THU AND RH/S WILL BE A LITTLE LOWER. THE
WINDS WILL BE MUCH LIGHTER ALSO ON THU...SO FIRE DANGER WILL BE
ELEVATED...BUT HITTING RFW CRITERIA SEEMS UNLIKELY.

&&

.HYDROLOGY...
ISSUED AT 339 AM EDT WED MAY 15 2013

THERE ARE NO HYDROLOGY CONCERNS FOR THE REMAINDER OF THIS WEEK AND
LIKELY THROUGH MOST OF THE WEEKEND. WE ARE EXPECTING VERY LITTLE IF
ANY RAINFALL THROUGH THE DAY ON SATURDAY. THE CHANCES OF RAIN WILL
ONLY INCREASE SUNDAY AND ESPECIALLY ON MONDAY. BY THIS TIME...RIVERS
WILL HAVE DROPPED MORE AND WILL BE ABLE TO HANDLE A DECENT AMOUNT OF
RAINFALL. WE COULD BE LOOKING AT AT LEAST BETWEEN HALF AN INCH TO AN
INCH. STILL A LOT OF TIME TO MONITOR LATEST TRENDS.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&

$$

SYNOPSIS...NJJ
SHORT TERM...NJJ
LONG TERM...DUKE
AVIATION...DUKE
FIRE WEATHER...NJJ
HYDROLOGY...NJJ
MARINE...WDM