Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 241030
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
630 AM EDT THU APR 24 2014

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 326 AM EDT THU APR 24 2014

HIGH PRESSURE OVER THE GREAT LAKES WILL MOVE EAST AND A COMPLEX LOW
PRESSURE SYSTEM WILL MOVE TOWARD THE GREAT LAKES. A FEW SHOWERS ARE
POSSIBLE THIS MORNING. HOWEVER MUCH OF TODAY WILL BE DRY. THE
GREATEST CHANCE OF RAIN WILL COME TONIGHT AS A COLD FRONTAL BOUNDARY
MOVES THROUGH LOWER MICHIGAN. TEMPERATURES WILL REMAIN BELOW AVERAGE
FOR MUCH OF THE NEXT WEEK AS COOLER AIR FROM CANADA FLOWS SOUTHWARD.

&&

.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 326 AM EDT THU APR 24 2014

FORECAST CONCERNS DEAL WITH RAIN CHANCES TODAY AND TONIGHT.

THE GOING FORECAST IS PRETTY MUCH ON TRACK. REGIONAL RADAR SHOWS
LIGHT RAIN ASSOCIATED WITH ISENTROPIC LIFT OVER WISCONSIN AND
ILLINOIS. A WARM FRONT WAS NOTED FROM SE WISCONSIN TO A LOW IN
SASKATCHEWAN. DEW POINTS WERE QUITE A BIT LOWER NORTH OF THE FRONT
AND THIS WAS HAVING AN EFFECT ON PCPN TO THE WEST. OBS OVER
WISCONSIN SHOW VERY LIGHT RAIN WITH VSBY MAINLY 10SM. AS THIS WARM
FRONT LIFTS NORTHWARD WE/LL SEE SOME LIGHT RAIN DEVELOP OVER THE WRN
CWA THIS MORNING BUT IT SHOULD ALSO BE RATHER LIGHT DUE TO THE DRY
AIR IN PLACE.

MUCH OF THIS AFTERNOON LOOKS DRY. ANOTHER PUSH OF MOISTURE WILL
ARRIVE TONIGHT AS A SECONDARY LOW OVER MISSOURI MOVES ENE TOWARD
INDIANA. THIS LOW COUPLED WITH THE SRN CANADA LOW WILL DRAG A COLD
FRONT TOWARD LOWER MICHIGAN. A DECENT LLJ AHEAD OF IT WILL PULL
MOISTURE NORTHWARD. LOW CONDENSATION PRESSURE DEFICITS COMBINED WITH
LIFT FROM THE FRONTAL BOUNDARY AND UPPER SHORT WAVES WILL RESULT IN
LIGHT RAIN OVER THE CWA TONIGHT. INSTABILITY LOOKS TOO WEAK TO
SUPPORT THUNDER TODAY/TONIGHT SO IT WAS LEFT OUT OF THE GRIDS.

FRIDAY AND SATURDAY LOOK MAINLY DRY AS HIGH PRESSURE NOSES SOUTH
FROM CANADA.

.LONG TERM...(SATURDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 326 AM EDT THU APR 24 2014

THE MAIN ISSUE REMAINS JUST HOW FAR NORTH THE RAIN GETS THIS COMING
WEEK WITH THE DEVELOPING CLOSED UPPER LOW. ONE HAS TO ASK IF AND
WHEN THE RAIN WOULD ACTUALLY SPREAD INTO SOUTHWEST LOWER MICHIGAN?
JUST HOW FAR NORTH WILL IT GET IF IT DOES GET INTO SOUTHWEST LOWER
MICHIGAN AT ALL? IT COULD BE ARGUE THE ENTIRE SYSTEM WILL STAY SOUTH
THROUGH THE WEEK (REX BLOCK ISSUES).

CURRENTLY WE HAVE ONE OF THE MORE EXTENSIVE EAST ASIA JET FEATURES
WE HAVE SEEN SO FAR THIS YEAR. CURRENTLY (06Z) IT EXTENDS FROM NEAR
JAPAN...ACROSS THE DATELINE TO NORTHERN CALIFORNIA AROUND 40N. THERE
IS A 160 KNOT CORE OF WINDS AROUND 45N JUST WEST OF THE DATELINE. IT
IS THAT FEATURE THAT WILL HELP CREATE THE STORM THAT RESULTS IN THE
STALLED UPPER LOW OVER THE MIDWEST THIS COMING WEEK. THE SPEED MAX
COMES ON SHORE OVER CALIFORNIA ON SUNDAY (26TH). IT THEN CLOSES OFF
AN UPPER LOW THAT SLOWLY MOVES EAST TO NORTHEAST ACROSS THE CENTRAL
UNITED STATES THROUGH THE REST OF THE WEEK.

AS THIS SYSTEM MOVES INTO THE WESTERN CONUS EARLY NEXT WEEK (WEEK OF
THE 26TH) IT PUMPS UP A MASSIVE UPPER RIDGE IN FRONT OF IT (OVER THE
WESTERN GREAT LAKES MONDAY).  MEANWHILE AN UPPER WAVE ROTATING
AROUND THE CLOSED OFF UPPER LEVEL SYSTEM OVER EASTERN CANADA AND THE
WESTERN NORTH ATLANTIC ROTATES WESTWARD ALMOST TO MICHIGAN BY
TUESDAY. IT THEN TAKES UNTIL WEDNESDAY FOR THAT TO GET OUT OF THE
WAY ENOUGH FOR THE SOUTHERN PLAINS SYSTEM TO GET CLOSE TO THE
SOUTHERN GREAT LAKES. ONCE THERE IT HOLDS IN PLACE INTO THE
FOLLOWING WEEKEND.

SO...IF AND WHEN WILL WE SEE RAIN OUT OF THIS SYSTEM?  WHAT SETS UP
AT THE SURFACE FROM ALL THIS IS LARGE CANADIAN POLAR HIGH CENTERED
OVER HUDSON BAY MOST OF NEXT WEEK. THAT WILL CONTINUE TO FEED IN DRY
AIR FROM THE EAST AND NORTHEAST MOST OF THE WEEK. MEANWHILE THE
SOUTHERN STREAM SYSTEM SETS UP A QUASI-STATIONARY FRONT THROUGH THE
OHIO VALLEY INTO THE CENTRAL PLAINS AS THAT SYSTEM SLOWLY HEADS EAST
NORTHEAST. OVERRUNNING RAIN WILL TRY TO MOVE IN AS EARLY AS SUNDAY
MORNING OVER OUR SOUTHERN COUNTIES BUT THE DRY IS SHOULD WIN OUT.
THROUGH MONDAY IT WOULD SEEM THE DRY AIR SHOULD LARGELY WIN AND IT
FOR THE MOST PART WILL STAY DRY OVER SOUTHWEST LOWER MICHIGAN. FROM
TUESDAY THROUGH WEDNESDAY AND WELL BEYOND THAT (LIKELY SAT OR SO) WE
SHOULD SEE PERIODIC SHOWERS. FOR THE MOST PART THIS DOES NOT LOOK
LIKE A HEAVY RAIN EVENT... JUST SHOWERS ON AND OFF. TEMPERATURES
WOULD FOR THE MOST PART BE JUST A TOUCH BELOW NORMAL.

BY WEDNESDAY NIGHT WE ARE EXPECTING LESS THAN A HALF INCH OF RAIN
NORTH OF INTERSTATE 96 WITH AROUND AN INCH NEAR AND SOUTH OF
INTERSTATE 94.

BOTTOM LINE...MOSTLY DRY SATURDAY NIGHT INTO MONDAY.... THEN A
CHANCE OF SHOWERS TUE AND WEDNESDAY. TEMPS MOSTLY IN THE 30S FOR
LOWS AND 50S FOR HIGHS.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 630 AM EDT THU APR 24 2014

VFR CONDITIONS ARE EXPECTED THROUGH MOST OF THE NEXT 24 HOURS.
THE SHOWERS OVER WISCONSIN AND LAKE MICHIGAN EARLY THIS MORNING WILL
CONTINUE TO RUN INTO DRY AIR OVER SOUTHWEST LOWER MICHIGAN SO EVEN
IF A FEW RAIN DROPS MAKE IT TO THE GROUND... THAT WOULD BE IT.
CEILINGS AND VISIBILITY SHOULD REMAIN SOLID VFR. IT WILL BECOME
WINDY THIS AFTERNOON WITH GUSTS TO 25 KNOTS EXPECTED. WINDS WILL
DIMINISH OVERNIGHT.

THE MAIN RAIN AREAS SHOULD MOVE INTO SOUTHWEST LOWER MICHIGAN
AFTER MIDNIGHT TONIGHT. THERE IS STILL A MAJOR QUESTION AS TO
WHERE IT WILL GO. SO IT IS NOT CERTAIN ALL THE TAF SITES WILL
ACTUALLY SEE THE RAIN TONIGHT. EVEN SO I ADDED RAIN AFT 09Z TO
MOST OF THE TAFS AND BROUGHT SOME MVFR CIGS/VSBY TO GO WITH THAT.


&&

.MARINE...
ISSUED AT 326 AM EDT THU APR 24 2014

WINDS WILL INCREASE TODAY AS LOW PRESSURE APPROACHES. THE SE FLOW
MEANS OFFSHORE WINDS AND WAVES WILL LIKELY REMAIN BELOW 3 FEET.
HOWEVER WINDS SHOULD INCREASE TO 15 TO 25 KNOTS AND SO WE/LL ISSUE A
SCA FROM EARLY AFTERNOON THROUGH TONIGHT.


&&

.HYDROLOGY...
ISSUED AT 1225 PM EDT WED APR 23 2014

IMPROVEMENT CONTINUES ON AREA RIVERS TODAY. EVART WILL LIKELY BE
THE LONE ADVISORY BEYOND 24 HOURS. A CANCELLATION IS ANTICIPATED
FOR SCOTTVILLE BY SOMETIME THIS EVENING/TONIGHT. CROTON DAM
OPERATIONS HAVE DROPPED LEVELS BELOW ADVISORY STAGE...WHICH WILL
SOON BE CANCELED.

MOISTURE RETURNS TO THE AREA LATE THURSDAY AND INTO FRIDAY.
RAINFALL WILL BE GREATEST OVER WESTERN AND NORTHWESTERN PORTIONS
OF LOWER MICHIGAN. TOTALS WILL GENERALLY BE AROUND ONE HALF AN
INCH. LESSER TOTALS WILL BE LIKELY FURTHER SOUTH AND EAST INTO
SOUTH CENTRAL LOWER MICHIGAN. THESE AMOUNTS ARE NOT ENOUGH TO
CREATE ANY CONCERN. THE EXTENDED FORECAST MAY WARRANT WATCHING FOR
RAINFALL AND COOLER WEATHER MOVING IN NEXT WEEK.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY FROM NOON TODAY TO 4 AM EDT FRIDAY FOR
     LMZ844>849.

&&

$$

SYNOPSIS...93
SHORT TERM...93
LONG TERM...WDM
AVIATION...WDM
HYDROLOGY...JAM
MARINE...93






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