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000
FXUS63 KGRR 170413
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1213 AM EDT FRI MAY 17 2013

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 313 PM EDT THU MAY 16 2013

THE SOUTHERN EDGE OF A VERY LARGE CANADIAN HIGH PRESSURE SYSTEM
WILL BUILD OVER LOWER MICHIGAN TONIGHT INTO SATURDAY BEFORE IT
BEGINS TO MOVE OUT OF THE AREA. THE DRY AIR WILL RESULT IN AN
ELEVATED FIRE DANGER INTO SATURDAY. SOME PATCHY FROST IS EXPECTED
NORTH OF ROUTE 10 AFTER MIDNIGHT TONIGHT.

A VERY SLOW MOVING STORM SYSTEM FROM THE WESTERN PLAINS WILL
REACH THE GREAT LAKES EARLY NEXT WEEK. THAT WILL BRING AN INCREASED
THREAT OF SHOWERS AND THUNDERSTORMS IN THE MONDAY THROUGH
WEDNESDAY TIME FRAME. TEMPERATURES WILL BE ABOVE NORMAL THROUGH
THE FIRST HALF OF NEXT WEEK.

&&

.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 313 PM EDT THU MAY 16 2013

LITTLE THREAT OF PRECIPITATION TONIGHT INTO SATURDAY THANKS TO A
LARGE CANADIAN HIGH THAT WILL CONTINUE TO FEED DRY CANADIAN AIR
INTO SOUTHWEST MICHIGAN INTO SATURDAY. THIS SAME DRY AIR WILL
ALLOW TEMPERATURES TO HAVE A LARGE DIURNAL RANGE. PATCHY FROST IS
EXPECTED NORTH OR ROUTE 10 AND EAST OF BALDWIN AFTER MIDNIGHT
TONIGHT.

LOOKING AT THE FROST POTENTIAL TONIGHT SURFACE DEW POINTS DURING
THE MID AFTERNOON ARE A GOOD INDICATION OF HOW COLD IT CAN GET AT
NIGHT. SINCE SURFACE DEW POINTS ARE ALREADY IN THE MID 30S FROM
BIG RAPIDS NORTH AND SINCE LEOTA HAD A LOW OF 34 LAST NIGHT IT
MAKES SENSE TO ME THAT PATCHY FROST IS POSSIBLE NEAR AND NORTH OF
ROUTE 10 AFTER MIDNIGHT. I DID NOT GO WITH FROST ADVISORY AS DEW
POINTS ARE NOT BELOW FREEZING... THAT TYPICALLY MEANS IT WILL BE
HARDER TO GET WIDESPREAD FROST.

WHILE SEVERAL SHORTWAVES TRAVEL ALONG THE POLAR JET... WHICH IS
LOCATED AND WILL REMAIN LOCATED OVER THE UPPER PENINSULA AND
NORTHERN LAKE HURON.... ANY MOISTURE THAT IS ASSOCIATED WITH THOSE
SHORTWAVES WILL ONLY BE AT MID AND HIGH LEVELS SO I DO NOT EXPECT
ANY PRECIPITATION FROM THESE SYSTEMS.

MOSTLY WHAT WE WILL SEE IS A LITTLE MORE IN THE WAY OF MID TO HIGH
LEVEL CLOUD COVER FRIDAY INTO SATURDAY BUT NOT ENOUGH TO KEEP
AFTERNOON TEMPERATURES FROM REACHING THE MID TO UPPER 70S BOTH
FRIDAY AND SATURDAY NORTH OF GRAND RAPIDS AND NEAR THE LAKE SHORE
BUT INTO THE LOWER 80S FROM GRAND RAPIDS SOUTH AND EAST.

.LONG TERM...(SUNDAY THROUGH THURSDAY)
ISSUED AT 313 PM EDT THU MAY 16 2013

FAIR AND SEASONABLY MILD WX WILL CONTINUE SUNDAY WITH MAX TEMPS IN
THE 70S AND PARTLY CLOUDY SKIES. TEMPERATURES WILL CONTINUE TO
AVERAGE AROUND FIVE TO TEN DEGREES ABOVE NORMAL EARLY NEXT WEEK AND
A LOW PRESSURE SYSTEM OVER THE UPPER MIDWEST WILL BRING A CHC OF
SHOWERS AND TSTORMS EARLY TO MIDWEEK.

FAIR WX IS EXPECTED TO RETURN LATE NEXT WEEK WITH 12Z GFS/00Z ECMWF
GUIDANCE SHOWING STRONG CANADIAN HIGH PRESSURE WILL GRADUALLY BUILD
SOUTH INTO OUR REGION. TEMPS LATE IN THE WEEK WILL LIKELY RETURN TO
NEAR NORMAL AS THAT OCCURS.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1204 AM EDT FRI MAY 17 2013

CONFIDENCE REMAINS VERY HIGH THAT WIDESPREAD VFR CONDITIONS WILL
CONTINUE OVERNIGHT AND FRIDAY WITH CLOUD BASES MOSTLY AT OR ABOVE 10K
FEET. SFC WINDS WILL BE EAST AT AROUND 10 KNOTS.

&&

.MARINE...
ISSUED AT 313 PM EDT THU MAY 16 2013

WITH CANADIAN HIGH PRESSURE OVER THE AREA INTO SATURDAY WINDS WILL
BE LIGHT SO I DO NOT EXPECT ANY ISSUES WITH STRONG WINDS OR LARGE WAVES.


&&

.FIRE WEATHER...
ISSUED AT 313 PM EDT THU MAY 16 2013

CANADIAN HIGH PRESSURE WILL CONTINUE TO FEED DRY AIR OFF THE
CANADIAN SHIELD INTO SATURDAY BEFORE WINDS BECOME MORE SOUTHEAST
BRINGING IN HIGHER DEW POINT AIR. THIS WILL RESULT IN VERY LOW
RELATIVE HUMIDITY`S (20-30 PCT) IN THE AFTERNOON FRIDAY AND
POSSIBLY SATURDAY. THE FIRE WEATHER THREAT INDEX VALUES ARE ON THE
HIGH SIDE SO THERE IS AN ELEVATED FIRE WEATHER THREAT. LIGHT WINDS
SHOULD SIGNIFICANTLY LOWER THE THREAT FOR RED FLAG WARNINGS.

&&

.HYDROLOGY...
ISSUED AT 313 PM EDT THU MAY 16 2013

NO SIGNIFICANT HYDRO ISSUES. THERE SHOULD BE AROUND AN INCH OF
RAIN OVER THE AREA BETWEEN MONDAY AND WEDNESDAY BUT THAT SHOULD
NOT BE ENOUGH TO RESULT IN ANY FLOODING PROBLEMS.

&&

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

$$

SYNOPSIS...WDM
SHORT TERM...WDM
LONG TERM...LAURENS
AVIATION...MEADE
FIRE WEATHER...WDM
HYDROLOGY...WDM
MARINE...WDM