FXUS63 KGRR 251743
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1243 PM EST WED NOV 25 2009

LATEST UPDATE...AVIATION...

.SYNOPSIS...(431 AM EST WED NOV 25 2009)
LOW PRESSURE WILL DRIFT OVER THE GREAT LAKES TODAY AND CONTINUE TO 
BRING ON AND OFF SHOWERS.  THESE SHOWERS WILL BE MOST COMMONPLACE 
EARLY TODAY...THEN BECOME SCATTERED INTO THE AFTERNOON.  MORE 
NUMEROUS SHOWERS ARE EXPECTED TONIGHT AS AN UPPER LOW MOVES IN.  
THIS SYSTEM WILL LINGER OVER THE REGION ON THANKSGIVING DAY.  AS 
COOLER AIR IS PULLED OVER THE AREA THE RAIN WILL BECOME MIXED WITH 
OR CHANGE TO SNOW THURSDAY AFTERNOON AND CONTINUE THURSDAY NIGHT.  A 
LIGHT SLUSHY ACCUMULATION OF SNOW WILL BE POSSIBLE BY EARLY FRIDAY 
MORNING...BUT TRAVEL SHOULD NOT BE HAMPERED AS ROADWAYS SHOULD 
REMAIN MAINLY WET.

&&

.SHORT TERM...(1155 AM EST WED NOV 25 2009)
(THIS AFTERNOON)
UPPER LOW IS SWINGING NORTHEAST OF THE AREA AT THIS TIME AND THE 
MORE CONCENTRATED AREA OF RAIN HAS COME TO AN END. EXPECTING ONLY 
SCATTERED SHOWERS THROUGH THE AFTERNOON. DOMINANT MODE OF 
PRECIPITATION THIS AFTERNOON MAY END UP BEING DRIZZLE AS THE MID 
LEVEL MOISTURE IS STRIPPED AWAY. FORECAST AREA IS IN BETWEEN THE 
LEAD UPPER LOW WHICH IS SHIFTING OFF TO THE NORTHEAST...AND THE 
SECOND LOW WHICH IS DIVING INTO IOWA. TEMPERATURES WILL ONLY CLIMB 
INTO THE UPPER 40S FOR HIGHS.

&&

.LONG TERM...(431 AM EST WED NOV 25 2009)
(FRIDAY NIGHT THROUGH TUESDAY)
UPPER LEVEL RIDGING INBETWEEN THE DEPARTING LONGWAVE TROUGH AND THE 
NEXT ONE DIGGING OVER THE WRN U.S. WILL RESULT IN DRY AND MILD 
CONDITIONS ON SATURDAY WITH HIGHS IN THE MID 40S. 

THINGS TURN RATHER COMPLICATED/CHALLENGING FOR SUNDAY THROUGH 
TUESDAY. A SFC FRONTAL BOUNDARY IS EXPECTED TO MOVE INTO THE REGION 
FROM THE WEST ON SUNDAY AND SHOULD BRING THE CHANCE FOR A FEW RAIN 
SHOWERS. UNFORTUNATELY MEDIUM RANGE MODELS DISAGREE ON WHAT HAPPENS 
AFTER THAT...BUT AN ENSEMBLE APPROACH WOULD SUGGEST THAT THE SFC 
BOUNDARY WILL EVENTUALLY STALL FROM THE EASTERN GREAT LAKES REGION 
SOUTH TO THE GULF OF MEXICO AS THE DEEP H5 LONGWAVE TROUGH EDGES 
SLOWLY EASTWARD. 

ANY POTENTIAL SHORTWAVES COMING OUT OF THE BASE OF THE LONGWAVE 
TROUGH OVER TEXAS AND RIDING NORTH NORTHEAST ALONG THE BAROCLINIC 
ZONE MAY PRODUCE SOME PCPN IN MI. THERE IS EVEN A SUGGESTION THAT A 
RATHER POTENT AND WET SYSTEM WILL LIFT STRAIGHT NORTH OUT OF THE 
GULF OF MEXICO TOWARD MI AND INTERACT WITH APPROACHING NRN STREAM 
ENERGY... BUT CONFIDENCE (AND TIMING) OF THAT HAPPENING IS VERY LOW 
ATTM. PCPN TYPE SHOULD BE RAIN OR A MIX OF RAIN AND SNOW MONDAY AND 
TUESDAY...DEPENDING HOW MUCH COLD AIR GETS INTO THE REGION BEHIND 
THE SFC FRONTAL BOUNDARY. 

&&

.AVIATION...(1243 PM EST WED NOV 25 2009)
MAIN CONCERN WITH THIS SET OF TERMINALS IS THE POTENTIAL OF IFR 
CONDITIONS OR LOWER THROUGH THE PERIOD. ESSENTIALLY WE CONTINUE TO 
THINK IFR WILL DOMINATE THROUGH 18Z THU. 

CONDITIONS ARE MAINLY MVFR OUT THERE RIGHT NOW...HOWEVER IFR 
CONDITIONS BACK IN WI ARE STARTING TO ROTATE EAST AND ARE NOW 
SHOWING UP OCCASIONALLY AT THE LAKESHORE. 950 MB RH ON THE MODELS 
HAVE A DECENT HANDLE ON THIS IFR...AND ROTATE THIS MOISTURE ACROSS 
THE TERMINALS THROUGH THE AFTERNOON. A FEW SHOWERS WILL OCCUR...AND 
MAY BRIEFLY BRING CONDITIONS DOWN AT TIMES.

WE EXPECT A MORE STEADY RAINFALL/AREA OF SHOWERS TO MOVE IN THIS 
EVENING AS THE NEXT WAVE UPSTREAM PHASES WITH THE CURRENT WAVE OVER 
THE STATE. THIS COMBINED WITH NIGHT TIME WILL ONLY HELP TO REINFORCE 
THE LOWER CIGS AND BRING SOME LOWER VSBYS IN. THIS WILL CONTINUE 
WELL INTO THANKSGIVING DAY MORNING BEFORE CONDITIONS MAY IMPROVE 
SLIGHTLY TOWARD 16-18Z THU.

&&

.MARINE...(431 AM EST WED NOV 25 2009)
WINDS AND WAVES WILL BE INCREASING THROUGH THE MORNING HOURS.  A 
SMALL CRAFT ADVISORY IS ALREADY IN EFFECT.  HOWEVER EVEN HIGHER 
WINDS AND WAVES SHOULD DEVELOP LATE TONIGHT INTO THURSDAY AS THE 
COLD ADVECTION ARRIVES.  SCA HEADLINES WILL LIKELY NEED TO BE 
EXTENDED WITH FUTURE FORECAST PACKAGES.

&&

.HYDROLOGY...(431 AM EST WED NOV 25 2009)
MOST AREAS WILL SEE AN ADDITIONAL QUARTER TO HALF INCH OF RAIN FROM 
TODAY THROUGH MIDNIGHT THURSDAY NIGHT.  THE PERSISTENT LIGHT PCPN 
WILL DO LITTLE TO INFLUENCE AREA RIVERS.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY ST. JOE TO WHITEHALL TODAY AND TONIGHT.

&&

$$

SYNOPSIS:     JK
SHORT TERM:   DUKE
LONG TERM:    MEADE
AVIATION:     NJJ
MARINE:       JK
HYDROLOGY:    JK