000
FXUS63 KGRR 121515
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1115 AM EDT SUN MAY 12 2013

LATEST UPDATE...
UPDATE/MARINE

.SYNOPSIS...
ISSUED AT 329 AM EDT SUN MAY 12 2013

A COLD DAY TODAY WILL SET THE STAGE FOR A FREEZE TONIGHT ACROSS MUCH
OF THE LOWER PENINSULA AS TEMPERATURES FALL INTO THE 20S. A WARMING
TREND WILL THEN DEVELOP AND BOOST TEMPERATURES INTO THE 80S BY
WEDNESDAY AND THE 70S THROUGH THE END OF THE WEEK. LOW CHANCES FOR
SHOWERS AND THUNDERSTORMS WILL EXIST MUCH OF THE WEEK.

&&

.UPDATE...
ISSUED AT 1108 AM EDT SUN MAY 12 2013

TWO CHANGES TO THE FORECAST. ADDED A SMALL CHANCE FOR MEASUREABLE
RAIN/SNOW SHOWERS TODAY. THIS WAS BASED OFF OF RADAR TRENDS. THE
SECOND CHANGE WAS TO LOWER THE WINDS TONIGHT...TAKING OUT THE
GUSTS TO 25 MPH THROUGH THE NIGHT.

&&

.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 329 AM EDT SUN MAY 12 2013

FORECAST CONCERNS DEAL WITH THE FREEZE TONIGHT. CONFIDENCE IS PRETTY
HIGH THAT WE/LL SEE A FREEZE ACROSS MUCH OF THE CWA. AS SUCH WE
UPGRADED THE WATCH TO A FREEZE WARNING BEGINNING AT 10 PM AND
CONTINUING OVERNIGHT.

LAKE EFFECT RAIN/SNOW SHOWERS WILL DIMINISH QUICKLY LATE THIS
AFTERNOON LEAVING MOSTLY CLEAR SKIES TONIGHT. AS WINDS DIMINISH VERY
GOOD RADIATIONAL COOLING CONDITIONS WILL DEVELOP. SINCE TEMPERATURES
WILL ONLY REACH THE UPPER 40S TODAY THEY WON/T HAVE FAR TO DROP TO
REACH FREEZING. LOOK FOR THE FREEZING TEMPS TO DEVELOP ACROSS THE
NRN CWA AROUND MIDNIGHT AND GRADUALLY PROGRESS SOUTHWARD OVERNIGHT.

WARMER WEATHER IS ON THE WAY AS THE DEEP UPPER TROUGH MOVES EAST
MONDAY. TEMPS WILL WARM SIGNIFICANTLY BY TUESDAY. A WARM FRONT
NOSING INTO THE REGION TONIGHT MAY KICK OFF A FEW SHOWERS.
ISENTROPIC LIFT IS IMPRESSIVE BUT WILL BE SHORT LIVED. AS THE WARM
FRONT SHARPENS TUESDAY WE COULD SEE A FEW THUNDERSTORMS. MUCAPE
VALUES IN THE 500-1000J/KG RANGE DEVELOP BY THE AFTERNOON AS LI/S
FALL BELOW 0C. LIFT FROM THE WARM FRONT MAY BE ENOUGH TO KICK OFF A
FEW STORMS.

.LONG TERM...(TUESDAY NIGHT THROUGH SATURDAY)
ISSUED AT 329 AM EDT SUN MAY 12 2013

OVERALL A SLIGHTLY WARMER THAN NORMAL TEMPERATURES AND LIMITED
PRECIPITATION SEEMS THE MOST LIKELY OUTCOME FOR MID TO LATE WEEK.
THIS IS THE RESULT OF THE UPPER LEVEL WAVE PATTERN BECOMING MORE
ZONAL BY THE MIDDLE OF NEXT WEEK.

THE MODELS CONTINUE TO FEATURE OUR CURRENTLY AMPLIFIED UPPER LEVEL
WAVE PATTERN BECOMING MORE ZONAL AS AN EXTENDED EAST ASIAN JET
DEVELOPS BETWEEN 30N AND 40N FROM NEAR JAPAN TO THE WEST COAST NORTH
OF CALIFORNIA... BY MONDAY AFTERNOON. THIS RESULTS IN A SPLIT FLOW
JET PATTERN WHERE THE POLAR BRANCH OF THE JET STREAM STAYS NORTH OF
65N WHILE THE SOUTHERN BRANCH RUNS NEAR 45N ACROSS THE NORTHERN
CONUS.

WE CONTINUE TO SEE THE ECMWF WEAKER WITH THE SYSTEM COMING ACROSS
THE NORTHERN STATES AND SOUTHERN CANADA THAN THE GFS FOR THE
WEDNESDAY TIME FRAME. THE ECMWF SEEMS TO HAVE GONE CLOSER TO THE
GFS THAN THE GFS TO THE ECMWF OVER THE PAST FEW DAYS. IN ANY EVENT
THE SPLIT FLOW PATTERN SEEMS TO LIMIT THE FLOW FROM THE GULF INTO
THE SYSTEM SO ANY RAINFALL FROM THE SYSTEM AS IT COMES THROUGH
WEDNESDAY SEEMS LIKE IT WOULD BE LIMITED AT BEST. PART OF THE
PROBLEM IS THE LOW LEVEL JET NEVER REALLY POINTS AT SOUTHWEST
MICHIGAN AND THE BEST DYNAMICS STAY NORTH OF THE GRR CWA. HELPING
THIS CAUSE FOR LIMITING THE PRECIPITATION POTENTIAL OVER SOUTHERN
MICHIGAN IS THE SOUTHERN STREAM LOW BEING SHEARED OUT. THAT HELPS
CUT OF THE BETTER MOISTURE SOUTH OF INTERSTATE 80 WEDNESDAY.

BEYOND WEDNESDAY... THE FRONT NOW SEEMS TO DROP FAR ENOUGH SOUTH SO
DRY WEATHER IS NOW EXPECTED THURSDAY. HOWEVER AN SHORTWAVE TRAVELING
ALONG IN THE ZONAL FLOW MAY ALLOW SOME SHOWERS AND THUNDERSTORMS IN
THE FRIDAY - SATURDAY TIME FRAME. TIMING THESE WAVES IN ZONAL FLOW
THIS FAR OUT IT TIME IS ALWAYS A CHALLENGE SO FOR NOW I WILL
CONTINUE THE LOW CHANCE POP FOR LATE WEEK AND CALL THAT GOOD.

ONE OTHER ASPECT TO ALL OF THIS...WEDNESDAY COULD TURN OUT TO BE A
VERY WARM DAY DEPENDING ON THE TIMING OF THE COLD FRONT AND THE
AMOUNT OF CLOUDS ASSOCIATED WITH IT. IT SHOULD BE THE WARMEST DAY OF
THE WEEK SINCE THAT IS THE ONLY DAY WE GET INTO THE WARM AIR FOR A
TIME. HIGHS SHOULD MAKE 80 OR MORE AT MOST INLAND AREAS.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 719 AM EDT SUN MAY 12 2013

MORE THAN ANYTHING ELSE IT WILL BE RATHER WINDY THIS MORNING INTO
THIS AFTERNOON. SURFACE WINDS SHOULD INCREASE TO 15 TO 25 MPH
WITH GUSTS NEAR 35 MPH AT TIMES BY 15Z.  CEILING WILL LOWER TO
MVFR DURING THIS MORNING ONLY TO INCREASE TO VFR CIGS BY MIDDAY.
AS THE SYSTEM PULLS OUT OF THE AREA THIS EVENING ...SKIES WILL
CLEAR FROM WEST TO EAST. WINDS WILL GO LIGHT AND VARIABLE... SO
THE CLEAR....CALM AND COLD WILL RULE THE NIGHT.


&&

.MARINE...
ISSUED AT 1108 AM EDT SUN MAY 12 2013

NO CHANGES TO THE MARINE FORECAST. GUSTS CONTINUE OVER SMALL CRAFT
CRITERIA. WEBCAMS SHOW BIGGER WAVES COMING ASHORE...ESPECIALLY
HOLLAND.  BUOY OFF OF HOLLAND HAS 7 FOOT WAVES.

&&

.FIRE WEATHER...
ISSUED AT 329 AM EDT SUN MAY 12 2013

COOL WEATHER WITH ISOLATED TO SCATTERED RAIN AND SNOW SHOWERS WILL
RESULT IN HIGHER RH VALUES TODAY. MUCH WARMER WEATHER WITH HIGHS IN
THE 80S ARE EXPECTED BY MID WEEK.

&&

.HYDROLOGY...
ISSUED AT 329 AM EDT SUN MAY 12 2013

LITTLE IN THE WAY OF HYDRO CONCERNS AS LIMITED RAINFALL IS EXPECTED
THROUGH THE WEEK.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...FREEZE WARNING FROM 10 PM THIS EVENING TO 8 AM EDT MONDAY FOR
     MIZ037>040-043>046-050>052-056>059-064>067-071>074.

LM...SMALL CRAFT ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR LMZ844>849.

&&

$$

UPDATE...MJS
SYNOPSIS...93
SHORT TERM...93
LONG TERM...WDM
AVIATION...WDM
FIRE WEATHER...93
HYDROLOGY...93
MARINE...MJS