Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 230350
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1150 PM EDT FRI AUG 22 2014

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 330 PM EDT FRI AUG 22 2014

WARM AND HUMID WEATHER WILL PREVAIL THROUGH AT LEAST THE MIDDLE PART
OF NEXT WEEK. THE HOTTEST DAYS WILL BE MONDAY AND TUESDAY WHEN HIGHS
MAY REACH 90 DEGREES WITH HEAT INDICES AS HIGH AS THE MID TO UPPER
90S. PRECIPITATION CHANCES WILL BE VERY LOW OVER THE NEXT SEVERAL
DAYS WITH ONLY AN ISOLATED SHOWER OR STORM POSSIBLE IN THE AFTERNOON
AND EARLY EVENING HOURS.

&&

.SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT)
ISSUED AT 330 PM EDT FRI AUG 22 2014

NOT A WHOLE LOT OF CHANGE EXPECTED SYNOPTICALLY OVER THE WEEKEND
WITH THE SFC WARM FRONT REMAINING SOUTH OF MI. MOIST/LIGHT LOW LEVEL
EASTERLY FLOW WITH SFC DEW PTS NEAR 70 SHOULD PROMOTE CONSIDERABLE
STRATUS/FOG AT NIGHT INTO THE MORNING HOURS. H8 TEMPS DONT CHANGE
MUCH EITHER WITH CONTINUED E/SE FLOW... IMPLYING SIMILAR HIGH TEMPS
OF MAINLY 80 TO 85 ALTHOUGH A BIT WARMER THAN THAT SW OF GRR
ESPECIALLY SUNDAY.

WILL KEEP THE FCST DRY ON SATURDAY DESPITE THE POSSIBILITY OF AN
ISOLATED SHOWER OR TWO. THE PROBABILITY IS REALLY ONLY AROUND 10
PERCENT. HEIGHT RISES AND DEVELOPING UPR RIDGE/SUBSIDENCE...
PARTICULARLY ON SUNDAY... SHOULD TEND TO SUPPRESS CONVECTIVE
DEVELOPMENT OVER THE WEEKEND.

IN THE NEAR TERM... THICK STRATUS DECK CONTINUES TO HANG TOUGH TODAY
OVER MUCH OF THE AREA EVEN AT MID AFTERNOON. INSTABILITY REMAINS
LIMITED WITH ML CAPES BELOW 1000 J/KG AND ITS BEEN DIFFICULT
GENERATING ANY DIURNAL CONVECTION. HAVE MAINTAINED A 20 POP THROUGH
MID EVENING SHOULD THE STRATUS BREAK SOON... ALTHOUGH IT SEEMS THE
ONLY AVAILABLE TRIGGER WOULD BE CONVERGENCE ALONG THE LAKE BREEZE
FRONT WHICH ALSO HAS HAD A HARD TIME DEVELOPING TODAY.

.LONG TERM...(MONDAY THROUGH FRIDAY)
ISSUED AT 330 PM EDT FRI AUG 22 2014

NO MAJOR CHANGES NEEDED TO THE LONG TERM PORTION OF THE FCST. THE
BEGINNING OF NEXT WEEK LOOKS VERY WARM AND HUMID. UPPER RIDGING IS
EXPECTED TO START OUT THE WEEK OVERHEAD...AND GRADUALLY GET
FLATTENED BY THE UPPER TROUGH LIFTING NE OUT OF THE PLAINS STATES.
WE CONTINUE TO THINK THAT THERE IS A VERY SMALL CHC OF A SHOWER OR
STORM ON MON...HOWEVER PLENTY OF CAPPING IS PRESENT OF FCST
SOUNDINGS WITH A WARM NOSE PRESENT ALOFT.

THE CHC OF RAIN WILL GRADUALLY INCREASE THEN INTO MID-WEEK...LOOKING
TO PEAK AROUND THE WED-WED NIGHT TIME FRAME RIGHT NOW. WE WILL SEE A
COLD FRONT DROP SOUTH INTO THE AREA ON TUE. THERE DOES NOT LOOK TO
BE MUCH FANFARE INITIALLY WITH THIS FRONT AS IT IS WEAKENING WITH
THE UPPER SUPPORT REMAINING WELL NORTH OF THE AREA. THE BEST CHC OF
RAIN WILL COME AS THE FRONT WILL BE STALLED OUT BY WED...AND ANOTHER
TROUGH MOVES TROUGH BRINGING A WAVE ALONG THE FRONT. QUITE A BIT OF
MOISTURE WILL BE AVAILABLE...SO HEAVY RAIN POTENTIAL WILL HAVE TO BE
WATCHED.

THE THINKING RIGHT NOW IS THAT WE SHOULD DRY OUT AND COOL OFF FOR
THE END OF NEXT WEEK. THE PREVIOUS MODEL RUNS HAVE BEEN SHOWING THE
TROUGH MOVING THROUGH AND PUSHING THE FRONT WELL SOUTH OF THE AREA.
SOME UNCERTAINTY HAS CROPPED UP AS THE NEW ECMWF HAS CLOSED OFF THE
UPPER LOW AND BRINGS AN ADDITIONAL WAVE IN AND ASSOCIATED PCPN FOR
THE END OF THE WEEK. WE TEND TO THINK FOR NOW THAT THE ECMWF IS
SHOWING ITS BIAS OF OVER-AMPLIFYING SYSTEMS TOO MUCH. WE HAVE LEFT
THU AND FRI DRY FOR NOW...AND WILL MONITOR THE LATEST TRENDS WITH
THIS TROUGH/LOW.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1149 PM EDT FRI AUG 22 2014

I CONTINUED THE IDEA OF DENSE FOG DEVELOPING ACROSS ALL OF THE TAF
SITES OVERNIGHT. ALREADY MANY SITES HAVE MVFR FOG. THE NAMDNG5
SHOWS FOG SPREADING INLAND FROM LAKE HURON AS FAR WEST AND GRR BY
12Z SATURDAY MORNING. ALREADY IT IS ON TRACK AS IT SHOWS THE FOG
INITIALLY MOVING INLAND OVER NORTHERN LOWER MICHIGAN (0SC/APN)
WHICH IN FACT IS ALREADY HAPPENING. LIKE YESTERDAY THE LOW CLOUDS
AND FOG SHOULD BE SLOW TO LEAVE SATURDAY. IT MAY BE MID TO LATE
AFTERNOON BEFORE THE LOW CLOUDS MIX OUT.

&&

.MARINE...
ISSUED AT 330 PM EDT FRI AUG 22 2014

VERY MOIST AIR MASS AND LIGHT WINDS WILL MAKE FOG PATCHES AND HAZY
CONDITIONS A POSSIBILITY ON LAKE MICHIGAN THROUGH THE WEEKEND.
VISIBILITIES MAY BE GREATLY REDUCED AT TIMES IN DENSE FOG PATCHES.


&&

.HYDROLOGY...
ISSUED AT 330 PM EDT FRI AUG 22 2014

THERE ARE NO HYDRO CONCERNS AT THIS TIME.

&&

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

$$

SYNOPSIS...MEADE
SHORT TERM...MEADE
LONG TERM...NJJ
AVIATION...WDM
HYDROLOGY...MEADE
MARINE...MEADE






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