Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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421
FXUS63 KGRR 200726
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
326 AM EDT WED MAY 20 2015

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

.SYNOPSIS...
ISSUED AT 326 AM EDT WED MAY 20 2015

EXPECT BELOW NORMAL TEMPERATURES THROUGH AT LEAST SATURDAY AS A
SERIES OF CANADIAN COLD FRONTS COME THROUGH THE AREA. THE NEXT
COLD FRONT COMES THROUGH EARLY FRIDAY MORNING AND THAT WILL BE
PRECEDED BY A FEW LIGHT RAIN SHOWERS THURSDAY EVENING. A WARM UP
IS EXPECTED TOWARD MEMORIAL DAY. SHOWERS AND THUNDERSTORMS ARE
POSSIBLE SUNDAY INTO TUESDAY.

&&

.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 326 AM EDT WED MAY 20 2015

LITTLE QUESTION THE PRECIPITATION FRONT NEXT SYSTEM WILL PASS
SOUTH OF LOWER MICHIGAN THIS AFTERNOON AND EVENING. THEN ANOTHER
DIGGING POLAR JET CORE WILL PUSH ANOTHER COLD FRONT THROUGH THE
AREA LATER THURSDAY NIGHT OR EARLY FRIDAY. IT LOOKS JUST MOIST
ENOUGH TO GET A FEW RAIN SHOWERS AHEAD OF THE COLD FRONT. BEYOND
THAT A CANADIAN HIGH MOVES IN BY MID MORNING FRIDAY ASSURING
MOSTLY CLEAR SKIES BUT COOLER TEMPEATURES.


.LONG TERM...(FRIDAY NIGHT THROUGH TUESDAY)
ISSUED AT 326 AM EDT WED MAY 20 2015

TWO MAIN CONCERNS IN THE EXTENDED...FIRST IS THE FROST THREAT ON
FRIDAY NIGHT AND THEN STORMY WEATHER FROM SUNDAY THROUGH TUESDAY.

SFC HIGH MOVES EAST BY 12Z SATURDAY...BUT RETURN FLOW MAY NOT BE
STRONG ENOUGH TO PREVENT FREEZING TEMPS UP NORTH AND SOME FROST
ESPECIALLY ACROSS EASTERN ZONES.

ONCE THE HIGH DEPARTS SATURDAY NIGHT...A RETURN FLOW SETS UP WITH
WARMER AND MORE HUMID AIR RETURNING BY MONDAY. ISENTROPIC ASCENT
NORTH OF THE SFC WARM FRONT SHOULD BRING SHOWERS BY SUNDAY MORNING
AND A SERIES OF WEAK WAVES MOVING ALONG STALLED WARM FRONT WILL
CONTINUE INTO TUESDAY. CONFIDENCE IS HIGH ON THE OVERALL PATTERN
ALTHOUGH THERE ARE THE USUAL DIFFERENCES IN THE DETAILS. OVERALL
THERE IS A HIGH CONFIDENCE OF SHOWERS AND A FEW THUNDERSTORMS
THROUGH THE PERIOD FROM SUNDAY TO TUESDAY.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1115 PM EDT TUE MAY 19 2015

WILL NEED TO MONITOR THE RISK FOR SHOWERS FOR SOUTHERN TAF SITES
KAZO...KBTL AND KJXN LATER WED AFTN INTO THE EVENING. AT THIS
TIME...EVEN IF THEY DO OCCUR...THE CONDITIONS SHOULD REMAIN VFR AS
THE LOW LEVEL MOISTURE WILL INITIALL REMAIN LIMITED. OTHERWISE THE
TAF SITES IN SOUTHWEST MI SHOULD SEE DIMINISHING WINDS INTO WED
AND RELATIVELY HIGH CLOUD BASES.


&&

.MARINE...
ISSUED AT 326 AM EDT WED MAY 20 2015

NOT MUCH TO WORRY ABOUT HERE. WINDS WILL NOT BE STRONG ENOUGH FOR
SMALL CRAFT ADVISORIES AND I DO NOT SEE THE THREAT OF
THUNDERSTORMS TILL AT LEAST SUNDAY.

&&

.HYDROLOGY...
ISSUED AT 140 PM EDT MON MAY 18 2015

IN GENERAL...RIVER LEVELS ACROSS SOUTHWEST LOWER MICHIGAN ARE
GRADUALLY FALLING. THAT WILL CONTINUE TO BE THE CASE WITH LIMITED
QPF THIS WEEK. FAIR WEATHER WILL DOMINATE FOR THE REST OF THE WEEK
INTO AT LEAST SATURDAY. THE NEXT SIGNIFICANT CHANCE FOR WIDESPREAD
RAINFALL WILL BE LATE IN THE HOLIDAY WEEKEND INTO NEXT WEEK.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...FROST ADVISORY UNTIL 8 AM EDT THIS MORNING FOR MIZ050-056>059-
     064>067-071>074.

     FREEZE WARNING UNTIL 8 AM EDT THIS MORNING FOR MIZ037>040-
     043>046-051-052.

LM...NONE.
&&

$$

SYNOPSIS...WDM
SHORT TERM...WDM
LONG TERM...OSTUNO
AVIATION...MJS
HYDROLOGY...EBW/CAS
MARINE...WDM



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