Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 200727
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
327 AM EDT SUN JUL 20 2014

LATEST UPDATE...
SYNOPSIS/SHORT TERM/LONG TERM/MARINE

.SYNOPSIS...
ISSUED AT 327 AM EDT SUN JUL 20 2014

FAIR WEATHER WILL CONTINUE TODAY THROUGH MONDAY INTO TUESDAY ALONG
WITH A CONTINUED GRADUAL MODERATING TREND OF TEMPERATURES. BY TUESDAY
HIGH TEMPERATURES MAY REACH THE 90 DEGREE MARK. A LOW PRESSURE
SYSTEM AND COLD FRONT WILL BRING SHOWERS AND THUNDERSTORMS TUESDAY
NIGHT INTO WEDNESDAY WITH COOLER TEMPERATURES FOR LATE IN THE WEEK.

&&

.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 327 AM EDT SUN JUL 20 2014

OUR PRIMARY SHORT TERM FCST CHALLENGE IS TO DETERMINE WHETHER ANY
CONVECTION WILL DEVELOP AS EARLY AS TUESDAY AFTERNOON.

FAIR WX WITH PARTLY CLOUDY SKIES AND A CONTINUED GRADUAL MODERATING
TREND OF TEMPS WILL CONTINUE TODAY THROUGH MONDAY INTO TUESDAY. IT
WILL ALSO GRADUALLY BECOME MORE HUMID MONDAY AND PARTICULARLY MONDAY
NIGHT AND TUESDAY AS DEW POINTS CLIMB WELL INTO THE 60S. MAX TEMPS
TODAY WILL REACH THE LOW TO PERHAPS MID 80S AND MID 80S ON MONDAY.
HIGH TEMPS TUESDAY WILL REACH THE 85 TO 90 DEGREE MARK.

WE WILL MAINTAIN MENTION OF JUST A SLIGHT CHANCE OF A SHOWER OR
THUNDERSTORM AS EARLY AS TUESDAY AFTERNOON OVER OUR NW FCST AREA
NW OF KGRR. THIS NOTION IS SUPPORTED BY THE 00Z ECMWF. HOWEVER A
CONSENSUS OF ALL THE LATEST SHORT RANGE COMPUTER MODEL GUIDANCE
SUGGESTS THAT THE BETTER CHC FOR PCPN WILL HOLD OFF UNTIL TUESDAY
EVENING/NIGHT AS THE FRONT MOVES INTO OUR AREA.

.LONG TERM...(TUESDAY NIGHT THROUGH SATURDAY)
ISSUED AT 327 AM EDT SUN JUL 20 2014

THE TREND WITH THE 00Z MODEL GUIDANCE HAS ONCE AGAIN BEEN QUICKER
WITH THE  PASSAGE OF THE COLD FRONT...WHICH NOW LOOKS TO BE THROUGH
THE FORECAST AREA BEFORE PEAK HEATING WEDNESDAY AFTERNOON. THIS ALSO
REDUCES THE SEVERE WEATHER RISK.  EXPECT BULK OF THE RAIN TO BE
TUESDAY NIGHT INTO WEDNESDAY MORNING.

SFC HIGH THEN BUILDS IN FOR THURSDAY AND FRIDAY...BEFORE WARM
ADVECTION BRINGS THE NEXT CHANCE FOR SHOWERS AND THUNDERSTORMS ON
SATURDAY.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1148 PM EDT SAT JUL 19 2014

I AM STILL THINKING DENSE FOG IS POSSIBLE AT LANSING AND JACKSON
DUE THE PERSISTENT EASTERLY FEED OF LOW LEVEL MOISTURE FROM LAKE
ERIE AND LAKE HURON. CURRENTLY (0330Z) SURFACE DEW POINTS ARE IN
THE LOWER TO MID 60S OVER THE EXTREME EASTERN PARTS OF LOWER
MICHIGAN. AS THAT AIR IS MIXED WITH THE SURFACE TEMPERATURES
COOLING TO NEAR 60 OVERNIGHT. I HAVE TO IMAGINE FOG WOULD DEVELOP
SINCE WINDS WILL BE LIGHT AND MIXING WILL BE MINIMAL. THIS IDEA OF
FOG IS SUPPORTED BY NEARLY ALL OF THE RUNS OF THE RAP13 MODEL
SINCE SINCE AT LEAST 19TH/21Z. THE 12Z...18Z AND 00Z RUN OF THE
NAM12 SHOW THIS TOO. THE FOG SHOULD MIX OUT QUICKLY AFTER SUNRISE.

AREAS CLOSER TO US-131 WILL HAVE A MORE WESTERLY LOW LEVEL WIND
AND THAT WILL KEEP THE AIR DRIER AND KEEP THE RISK OF FOG AT A
MINIMUM.

SUNDAY DURING THE DAY WILL MOSTLY SUNNY WITH LIGHT WINDS. HIGH
BASED CUMULUS CLOUDS SHOULD DEVELOP BY LATE MORNING BUT A STRONG
SUBSIDENCE INVERSION NEAR 10000 FT AGL SHOULD KEEP THE CLOUDS FROM
GETTING DEEP ENOUGH TO RESULT IN RAIN SHOWERS.


&&

.MARINE...
ISSUED AT 327 AM EDT SUN JUL 20 2014

MINIMAL WIND AND WAVE ACTION IS ANTICIPATED TODAY THROUGH MONDAY
WITH FAIRLY LIGHT AND VARIABLE WINDS AND WAVE HEIGHTS UNDER 2
FEET. PATCHY FOG MAY DEVELOP MONDAY AND TUESDAY AS A WARMER AND
MORE HUMID AIRMASS MOVES IN.

&&

.HYDROLOGY...
ISSUED AT 321 PM EDT SAT JUL 19 2014

NO HYDROLOGY ISSUES EXPECTED THROUGH EARLY NEXT WEEK WITH NO RAIN IN
THE FCST UNTIL AT LEAST TUESDAY. RIVER LEVELS/FLOWS RANGE FROM
NORMAL TO MUCH ABOVE NORMAL THIS AFTERNOON...BUT ARE IN THE PROCESS
OF COMING DOWN WITH DRY WEATHER THE LAST COUPLE OF DAYS. MAPLE
RAPIDS IS THE ONLY FLOOD ADVISORY OUT YET. THIS IS JUST BARELY ABOVE
BANKFULL STAGE...AND SHOULD DROP BELOW IT WITHIN THE NEXT 24 HOURS.

&&

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

$$

SYNOPSIS...LAURENS
SHORT TERM...LAURENS
LONG TERM...OSTUNO
AVIATION...WDM
HYDROLOGY...NJJ
MARINE...LAURENS








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