Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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000
FXUS63 KGRR 110028
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
828 PM EDT THU JUL 10 2014

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 306 PM EDT THU JUL 10 2014

AN AREA OF HIGH PRESSURE CENTERED OVER THE GREAT LAKES REGION WILL
TRACK EASTWARD THROUGH FRIDAY. THIS FAIR WEATHER SYSTEM WILL
DOMINATE OUR WEATHER BY KEEPING IT DRY. A WARM FRONT WILL ARRIVE
FRIDAY NIGHT AND BECOME NEARLY STATIONARY THROUGH SATURDAY. A LOW
PRESSURE SYSTEM WILL THEN TRACK THROUGH MICHIGAN BY SUNDAY. AS A
RESULT THE WEATHER WILL TURN UNSETTLED FOR THE WEEKEND.

&&

.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 306 PM EDT THU JUL 10 2014

THE MAIN CHALLENGE DEALS DEALS WITH THE IMPACT OF THE STORMS FRI
NIGHT INTO SAT. OVERALL GIVEN THE HIGH PRECIPITABLE WATER AIRMASS
THAT WILL BE IN PLACE...AN ELEVATED RISK FOR HEAVY RAIN EXISTS.

ALL MODELS ARE IN DECENT AGREEMENT IN TRACKING THE WARM FRONT UP
INTO LOWER MI THEN STALLING IT WOULD. MOISTURE POOLS ALONG THIS
FRONT AND PWAT VALUES CLIMB TO OVER 2 INCHES SATURDAY AND REMAIN
THERE INTO THE NIGHT. ELEVATED INSTABILITY IS SHOWN...AND AT THIS
POINT IT LOOKS RELATIVELY WEAK. GOOD SHEAR ARRIVES...ESPECIALLY
SAT INTO SAT NIGHT WHEN A LOW LEVEL JET TRACKS EASTWARD ALONG THIS
STALLED FRONT. ALOFT THE FLOW IS DIFFLUENT. GENERALLY THIS PATTERN
AT TIMES LEADS TO EXCESSIVE RAIN. WHILE NOT CERTAIN TO
HAPPEN...THIS WILL BE SOMETHING WE NEED TO MONITOR CLOSELY. I WILL
INCREASE POPS AND FEATURE SOME HEAVIER RAIN IN THE QPF. AT THIS
POINT SOUTHERN PARTS OF LOWER MI APPEAR FAVORED FOR THE HEAVY RAIN.

THE HIGH PRESSURE SYSTEM IN CONTROL OF OUR WEATHER WILL KEEP IT
COOLER THAN NORMAL. TEMPERATURES WILL START TO MODERATE ON FRIDAY
AS THE WINDS BECOME SOUTHERLY.

.LONG TERM...(SUNDAY THROUGH THURSDAY)
ISSUED AT 306 PM EDT THU JUL 10 2014

THE CHANCE OF SHOWERS AND THUNDERSTORMS WILL REMAIN IN THE FORECAST
SUNDAY THROUGH MONDAY AS THE UNSETTLED WX PATTERN CONTINUES AS
ANOTHER LOW PRESSURE WAVE AND STRONG COLD FRONT MOVES THROUGH EARLY
NEXT WEEK.

A SIGNIFICANT WX PATTERN CHANGE WILL OCCUR TUESDAY AND WEDNESDAY AS
AN UPPER LEVEL TROUGH MOVES IN AND AMPLIFIES OVER THE GREAT LAKES
REGION. UNSEASONABLY COOL WX IS ANTICIPATED TUESDAY THROUGH
WEDNESDAY WITH BRISK NORTH TO NW FLOW CAA.

MAX TEMPS WILL STRUGGLE TO REACH THE UPPER 60S TO LOWER 70S WITH
DIURNALLY DRIVEN SCATTERED SHOWERS POSSIBLE DUE TO DAYTIME HEATING
AND WITH THE COLD POOL ALOFT UNDER THE UPPER TROUGH AXIS.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 827 PM EDT THU JUL 10 2014

VFR CONDITIONS ARE EXPECTED THE NEXT 24 HOURS. SOME CIRRUS CLOUD
WILL SPREAD IN LATE TONIGHT AND ON FRIDAY...WITH BASES AT 20000FT
OR HIGHER. SCATTERED CUMULUS CLOUD DEVELOPMENT IS EXPECTED ON
FRIDAY WITH BASES AROUND 5000FT.

WINDS WILL BE LIGHT AND VARIABLE TONIGHT WITH HIGH PRESSURE STILL
IN CONTROL OVER THE REGION. ON FRIDAY...THE HIGH WILL START TO
SLIDE EAST...WHICH WILL ALLOW SOME LIGHT SOUTH WINDS OF 5-10 KNOTS
TO DEVELOP.

&&

.MARINE...
ISSUED AT 306 PM EDT THU JUL 10 2014

THE FLOW REMAINS RELATIVELY WEAK THROUGH FRIDAY. THE PRESSURE
GRADIENT TIGHTENS UP OVER THE WEEKEND. THUS...WAVES WILL LIKELY BE
BUILDING THEN. NOT CONFIDENT ENOUGH TO GO WITH SMALL CRAFT
ADVISORIES AT THIS POINT.


&&

.FIRE WEATHER...
ISSUED AT 306 PM EDT THU JUL 10 2014

DRY THROUGH FRIDAY. RH VALUES LIKELY TO DROP CONSIDERABLY FRIDAY
ONCE AGAIN. WINDS DO NOT SUPPORT ANY RED FLAG WARNINGS.  MORE RAIN
IS ON THE WAY FOR THE WEEKEND.

&&

.HYDROLOGY...
ISSUED AT 306 PM EDT THU JUL 10 2014

POTENTIAL FOR HEAVY RAIN AGAIN SATURDAY INTO SATURDAY NIGHT. COULD
BE EXCESSIVE IN PLACES. NOT TOO OFTEN WE SEE PWAT VALUES CLIMBING
OVER 2 INCHES. SOUNDINGS ARE SHOWN TO BE MOIST WITH LOW
LCLS...AND SUGGEST WEAK UPDRAFTS. COULD BE WARM RAIN PROCESSES
LEADING TO INCREASED EFFICIENCY. SUSPECT THE LOW LEVEL JETS WILL
FOCUS THE HEAVIEST RAIN. RIGHT NOW IT LOOKS LIKE SATURDAY AFTN
INTO THE EVENING WILL BE THE TIME FRAME OF MOST CONCERN.

&&

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

$$

SYNOPSIS...MJS
SHORT TERM...MJS
LONG TERM...LAURENS
AVIATION...DUKE
FIRE WEATHER...MJS
HYDROLOGY...MJS
MARINE...MJS







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