988
FXUS63 KGRR 072109
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
400 PM EST SAT NOV 7 2009
LATEST UPDATE...ALL SECTIONS BUT AVIATION...
SYNOPSIS
(400 PM EST SAT NOV 7 2009)
A WEAK AND DRY COLD FRONT MOVING EAST THROUGH THE GREAT LAKES REGION
THIS EVENING WILL STALL IN A WEST TO EAST FASHION LATE TONIGHT OVER
SOUTHERN MICHIGAN THEN LIFT BACK NORTH AS A WARM FRONT ON SUNDAY.
ANOTHER MOSTLY SUNNY AND UNSEASONABLY WARM DAY CAN BE EXPECTED
SUNDAY WITH HIGHS IN THE LOWER TO MIDDLE 60S. WINDS WILL BE MUCH
LIGHTER THAN ON SATURDAY.
A COLD FRONT APPROACHING FROM THE WEST WILL BRING THE POSSIBILITY OF
SOME RAIN SHOWERS AND POSSIBLY A THUNDERSTORM MONDAY AFTERNOON AND
MONDAY NIGHT.
SHORT TERM
(400 PM EST SAT NOV 7 2009)
(TONIGHT THROUGH MONDAY)
TEMPERATURES GOT A LITTLE WARMER THAN EXPECTED TODAY DESPITE LOW
MIXING LEVEL HEIGHTS AROUND 900 MB. HAVE KEPT THAT IN MIND FOR
SUNDAY/S HIGH TEMP FCST AND WENT MID 60S AGAIN.
LOW CLOUDS NEVER REALLY MANAGED TO DEVELOP ALONG THE FRONT TODAY SO
HAVE WENT WITH AN OPTIMISTIC SKY FCST TONIGHT AND SUNDAY. THAT
SAID... THERE IS STILL A POSSIBILITY THAT WE WILL SEE SOME CLOUDS
DEVELOPING ALONG THE BOUNDARY YET... ESPECIALLY LATE TONIGHT AND
SUNDAY MORNING BEFORE THE BOUNDARY LIFTS BACK NORTH.
THE NAM AND ECMWF ARE QUICKER THAN THE GFS IN PUSHING THE NEXT COLD
FRONT THROUGH MONDAY AFTERNOON AND NIGHT. GFS IS ALSO MOST
AGGRESSIVE WITH QPF IN RESPONSE TO NARROW BUT STRONG RIBBON OF MID
LEVEL FGEN FORCING AND INSTABILITY. CONVECTIVE POST FRONTAL FGEN
BANDS ARE VERY TOUGH TO NAIL IN BOTH TIME AND SPACE... SO FOR NOW
HAVE MAINTAINED CHANCE POPS FOR RAIN SHOWERS AND ISOLD THUNDER OVER
THE ENTIRE CWFA MONDAY AFTERNOON AND NIGHT. HIGHEST POPS MONDAY
NORTHWEST AND HIGHEST POPS MONDAY NIGHT SOUTHEAST.
LONG TERM
(400 PM EST SAT NOV 7 2009)
(TUESDAY THROUGH SATURDAY)
MAIN CHALLENGES IN THE LONG TERM ARE DETERMINING ANY LINGERING PCPN
CHCS ON TUE MORNING WITH THE DEPARTING SYSTEM...AND HOW FAST TO
BRING IN PCPN FOR THE END OF NEXT WEEK. ASIDE FROM THESE PCPN
CHCS...MOST OF THE LONG TERM LOOKS DRY AND MILD.
WE HAVE ADDED SOME RAIN BACK IN ACROSS THE SE HALF OF THE CWFA TUE
MORNING. NEARLY ZONAL UPPER FLOW CURRENTLY IN PLACE IS EXPECTED TO
AMPLIFY A BIT BY THE BEGINNING OF THE LONG TERM TUE MORNING. THE
FIRST STRONGER TROUGH IN THE SERIES WILL BE MOVING EXITING THE STATE
DURING THE DAY ON TUE. MODELS DIFFER A BIT IN THE STRENGTH AND
RESULTING TIMING OF THE WAVE...BUT ALL LINGER PCPN INTO AT LEAST
PART OF TUE. WE BELIEVE THE LESS AMPLIFIED AND QUICKER EURO AND 12Z
GFS ENSEMBLE MEAN...WHICH WILL END PCPN BY TUE AFTERNOON.
A FAIRLY DRY AND MILD PERIOD IS THEN EXPECTED AT LEAST LATE TUE
THROUGH THU NIGHT...IF NOT INTO FRI NIGHT. LONG WAVE TROUGH WILL BE
DIGGING ACROSS THE WRN HALF OF THE CONUS AS THE UPPER JET SPLITS AND
TAKES SOME ENERGY NORTH. RIDGE WILL BUILD ACROSS THE ERN HALF OF THE
US AND ALLOW FOR THE MILD WX.
UNCERTAINTY MOVES INTO THE PICTURE AROUND FRI AND INTO SAT REGARDING
THE TIMING OF THE NEXT FRONTAL SYSTEM INTO THE AREA. GFS HAS SLOWED
DOWN THE TIMING OF THE FRONT INTO THE AREA UNTIL NEXT SAT...VERY
SIMILAR TO THE 00Z EURO. 12Z GFS ENSEMBLE IS SHOWING A SAT FRONTAL
TIMING ALSO. NEW 12Z EURO HAS SPED THE FRONT UP AS THE NRN ENERGY
THAT SPLITS IS SHOWN TO BE A BIT STRONGER AND FARTHER SOUTH. WE WILL
SIDE WITH THE CONSENSUS AND MAINTAIN THE DRY FCST FOR FRI...AND ADD
IN RAIN FOR SAT. THIS COULD EVEN BE EARLY IF THE TREND FOR THE SRN
STREAM TROUGH IS TO CLOSE OFF MORE.
AVIATION
(1252 PM EST SAT NOV 7 2009)
VFR CONDITIONS WITH OCCASIONALLY GUSTY WINDS ARE EXPECTED THIS
AFTERNOON. VISIBLE SATELLITE IMAGERY INDICATED A FEW CLOUDS AROUND
2K TO 3K FT ACROSS CENTRAL LOWER MI...SO INCLUDED A MENTION OF THOSE
FOR MKG...GRR...AND LAN. OTHERWISE...VFR CONDITIONS SHOULD CONTINUE
FOR THOSE AFOREMENTIONED TAF SITES THROUGH THE PERIOD. MODELS ARE
INDICATING AN INCREASE IN MOISTURE DURING THE MID TO LATE MORNING
HOURS SUNDAY AND BEYOND... PARTICULARLY AROUND THE I-94 CORRIDOR...
AND BR IS POSSIBLE FOR THE SOUTHERN TAFS AS RADIATIONAL COOLING
PEAKS TOMORROW MORNING AND WINDS DIE OFF. NOT EXPECTING CONDITIONS
TO GET WORSE THAN MVFR. DECIDED TO HOLD OFF ON MENTION OF LOWER
CLOUDS IN ASSOCIATION WITH THE WARM FRONTAL PASSAGE LATE TOMORROW
MORNING OR EARLY AFTERNOON...AS IT WILL BE CLOSE TO THE END OF THE
PERIOD AND FUTURE TAF ISSUANCE WILL BETTER DETERMINE THIS THREAT.
MARINE
(400 PM EST SAT NOV 7 2009)
GRADIENT IS RELAXING WITH FRONTAL BOUNDARY NOW MOVING IN. WINDS AND
WAVES WILL SUBSIDE RATHER QUICKLY LATE THIS AFTERNOON AND EARLY THIS
EVENING. SMALL CRAFT ADVISORIES WILL PROBABLY BE NEEDED AGAIN ON
SUNDAY NIGHT INTO MONDAY AS SOUTH FLOW STRENGTHENS AGAIN AHEAD OF
NEXT APPROACHING COLD FRONT.
HYDROLOGY
(400 PM EST SAT NOV 7 2009)
NARROW BAND OF QPF UP TO ONE HALF INCH POSSIBLE MONDAY AND MONDAY
NIGHT. THIS SHOULD HAVE LITTLE IMPACT ON HYDRO.
GRR WATCHES/WARNINGS/ADVISORIES
MI...NONE.
LM...SMALL CRAFT ADVISORY ST. JOSEPH TO MANISTEE THROUGH 7 PM.
SYNOPSIS: MEADE
SHORT TERM: MEADE
LONG TERM: NJJ
AVIATION: HOVING/NJJ
MARINE: MEADE
HYDROLOGY: MEADE
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