Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 201125
AFDGRR

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

LATEST UPDATE...
AVIATION

.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 EVENT ASSOCIATED WITH THE NEXT
SYSTEM WILL PASS SOUTH OF LOWER MICHIGAN THIS AFTERNOON AND
EVENING. THEN... ANOTHER DIGGING POLAR JET CORE FROM NORTHERN
CANADA WILL PUSH ANOTHER COLD FRONT THROUGH THE AREA LATER
THURSDAY NIGHT OR EARLY FRIDAY. THERE IS JUST MOIST LOW TO MID
LEVEL MOISTURE 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 TEMPERATURES. SOME FROST
WILL BE POSSIBLE SATURDAY MORNING.

EARLY THIS WEDNESDAY MORNING WE HAVE A SOUTHERN STREAM SYSTEM
CAUSING AN AREA OF RAIN AND THUNDERSTORMS NEAR THE MISSISSIPPI
RIVER. IT IS CURRENTLY HEADING EASTWARD AND WOULD NORMALLY
BRING RAIN TO OUR AREA TODAY.  HOWEVER THIS TIME WE HAVE A
DIGGING NORTHERN STREAM SHORTWAVE AND ASSOCIATED  POLAR JET CORE
HEADING FOR THE WESTERN GREAT LAKES. THAT WILL FORCE THE SOUTHERN
STREAM SYSTEM SOUTH OF MICHIGAN THIS AFTERNOON AND EVENING. WE
WILL SEE CONSIDERABLE HIGH AND MID CLOUDS TODAY WITH AREAS NEAR
I-94 SEEING THE THICKER CLOUDS WHILE AREA NORTH OF I-96 WILL HAVE
CONSIDERABLE MORE SUNSHINE. EVEN SO IT WILL NOT GET ALL THAT WARM
TODAY...HIGHS SHOULD MOSTLY BE IN THE 50S. SOME CLEARING IS
EXPECTED TONIGHT WITH LIGHTER WINDS SO NORTHERN AREA COULD SEE A
LITTLE PATCHY FROST.

MEANWHILE A CLOSED...COLD CORE UPPER LOW...CURRENTLY NEAR BAFFIN`SISLAND
DROPS SOUTHWARD...REACHING SOUTHERN HUDSON BAY THURSDAY MORNING.
THIS WILL BRING ANOTHER COLD FRONT THROUGH THE AREA LATE THURSDAY
NIGHT. THERE WILL BE JUST ENOUGH LOW TO MID LEVEL MOISTURE AND
LIFT AHEAD OF THE COLD FRONT TO CREATE A LIGHT RAIN SHOWERS.
CLEARING WILL QUICKLY FOLLOW BY MID MORNING FRIDAY.

.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...RETURN FLOW STRENGTHENS
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 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 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 725 AM EDT WED MAY 20 2015

SOME MVFR CONDITIONS NEAR JXN THIS MORNING WITH CEILINGS AROUND
2500 FEET AGL AT TIMES. ELSEWHERE...VFR CONDITIONS EXPECTED
THROUGH TONIGHT WITH WINDS BELOW 10 KNOTS.

&&

.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...OSTUNO
HYDROLOGY...EBW/CAS
MARINE...WDM


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