Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 301925
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
325 PM EDT TUE SEP 30 2014

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

.SYNOPSIS...
ISSUED AT 325 PM EDT TUE SEP 30 2014

THE WEATHER WILL REMAIN QUIET TONIGHT AND WEDNESDAY.  WE WILL SEE
MORE SUNSHINE WEDNESDAY WHICH WILL BOOST TEMPERATURES INTO THE MID
AND UPPER 60S.  HOWEVER WE WILL BE ENTERING A WET PERIOD STARTING
LATE WEDNESDAY NIGHT INTO THURSDAY AND LASTING THROUGH SATURDAY.  A
SOAKING RAIN APPEARS LIKELY WITH SOME AREAS SEEING UP TO TWO INCHES
OF RAINFALL.

AFTER A WARMER DAY ON THURSDAY...WITH HIGHS FROM 70 TO 75...WE WILL
COOL DOWN FOR THE WEEKEND WITH HIGHS ONLY IN THE 50S.  WE SHOULD SEE
TEMPERATURES WARM BY TUESDAY WITH HIGHS REACHING AROUND 60.

&&

.SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT)
ISSUED AT 325 PM EDT TUE SEP 30 2014

QUIET WEATHER FOR THE NEXT 24 HOURS.  WE WILL HANG ON TO THE CLOUDS
THROUGH MUCH OF THE NIGHT AS THE LOW LEVELS REMAIN MOIST.  HOWEVER
WITH UPPER RIDGING MOVING IN CLEARING WILL START BY MID MORNING
WEDNESDAY FROM THE SW...AND BY MID AFTERNOON OVER THE NE CWA.  THIS
CLEARING IS SLIGHTLY DELAYED SO TEMPS MAY STRUGGLE A BIT.  I TRIMMED
MAX TEMPS SLIGHTLY...BUT STILL FEEL MID AND UPPER 60S WILL BE
ACHIEVED.

THEN WE WILL ENTER A WET PERIOD...OVER THE WESTERN CWA LATE
WEDNESDAY NIGHT...AND ADVANCING TO THE EASTERN CWA BY THURSDAY.
DEEP SOUTHWEST FLOW WILL SET UP OVER THE GREAT LAKES AS RIDGING IS
SEEN OVER THE EASTERN SEABOARD...WITH UPPER TROUGHING OVER THE
PLAINS.  A SURFACE COLD FRONT WILL ONLY SLOWLY PROGRESS EAST ACROSS
THE UPPER MIDWEST INTO THE WESTERN GREAT LAKES FROM WED NIGHT INTO
THU NIGHT.  UPPER DIVERGENCE FROM THE RIGHT ENTRANCE REGION OF THE
UPPER JET SETS UP OVER LOWER MICHIGAN THURSDAY AFTERNOON AND IS
MAINTAINED THROUGH THURSDAY NIGHT WHEN THE BULK OF THE RAIN IS
EXPECTED.  INCREASED POPS FOR THURSDAY NIGHT AND ALSO BUMPED MINS UP
GIVEN THE STRONG SOUTHERLY FLOW AND CLOUD COVER.

WITH THE DEEP SW FLOW GULF MOISTURE WILL BECOME ABUNDANT AS
PRECIPITABLE WATER VALUES SPIKE TOWARD 1.75 INCHES THURSDAY
EVENING.  WITH THE SLOW NATURE OF THE SYSTEM THE NW CWA APPEARS MOST
LIKELY TO SEE THE HEAVIEST RAINS...WHICH COULD APPROACH TWO INCHES
BY FRIDAY MORNING.  THE SEVERE WEATHER THREAT APPEARS LOW AT THIS
POINT DUE TO WEAK INSTABILITY...AND THE FACT THAT THE BEST UPPER
DYNAMICS DOES NOT COME IN UNTIL THURSDAY NIGHT.  45 KNOTS OF WIND IS
PROGGED OVER SW MI AT 2K FEET THURSDAY NIGHT...WHICH A STRONGER
STORM COULD MIX DOWN...MAKING FOR ISOLATED STRONG WIND GUSTS.

.LONG TERM...(FRIDAY THROUGH TUESDAY)
ISSUED AT 325 PM EDT TUE SEP 30 2014

THE COLDEST WEATHER WE HAVE SEEN SINCE THE MIDDLE OF MAY SHOULD MOVE
INTO THE AREA FRIDAY. THE CHILLY AIR APPEARS TO PERSIST THROUGH THE
WEEKEND INTO EARLY NEXT WEEK BEFORE THE SYSTEM FINALLY MOVES OUT OF
THE AREA AND ANOTHER WARM UP STARTS.  LAKE EFFECT RAIN SHOWERS
SHOULD CONTINUE THROUGH THE WEEKEND.

THE MODELS HAVE COME TOGETHER NOW ON HOW THIS WILL PLAY OUT. ALL OF
THEM NOW SHOW A CLOSED UPPER LOW OVER THE GREAT LAKES SATURDAY INTO
SUNDAY. HOWEVER AS IT LIFTS OUT SATURDAY NIGHT ANOTHER SHORTWAVE
FOLLOWS IT...WHICH KEEPS SOUTHWEST LOWER MICHIGAN IN THE COLD
UNSTABLE AIR INTO EARLY TUESDAY.

850 MB TEMPERATURES FALL INTO THE -1C TO -3C RANGE BY FRIDAY NIGHT
THEN CONTINUING INTO MONDAY NIGHT.  GIVEN THE MOSTLY WESTERLY WINDS
THROUGH THE PERIOD....LITTLE QUESTION LAKE EFFECT RAIN SHOWERS WILL
CONTINUE INTO MONDAY. WATER SPOUTS MAY BE AN ISSUE TOO.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1308 PM EDT TUE SEP 30 2014

I EXPECT MVFR CIGS TO PREVAIL THROUGH THE NEXT 24 HOURS AT ALL TAF
SITES. THIS IS CURRENTLY THE CASE AT TAF SITES.

THE RAP...NAM AND GFS ALL SUGGEST THE CLOUDS WILL BREAK OUT FROM
US-131 TO THE LAKE SHORE EARLY THIS AFTERNOON THEN FILL IN ONCE
AGAIN TONIGHT. GIVEN THAT THE SURFACE LOW IS PULLING AWAY FROM THE
AREA AND HIGH PRESSURE IS BUILDING INTO THE AREA TO REPLACE IT.
THAT SUGGESTS ANTICYCLONIC LOW LEVEL WINDS SHOULD PREVAIL BY MID
AFTERNOON. NORMALLY THAT WOULD CLEAR OUT THE CLOUDS. ADD TO THAT
IDEA THAT THE UPPER JET CORE IS ALREADY MOVING EAST OF THE CWA
ALSO SUGGESTS THE LOW CLOUDS SHOULD BE CLEARING OUT. IT THEN WOULD
BE LOGICAL TO CLEAR THE CLOUDS OUT OF THE TAF SITES BY 21Z OR SO.
HOWEVER... A WISE FORECASTER WHO HELPED TRAIN ME MANY YEARS
AGO...WHO HAS LONG SINCE RETIRED...SAID WHEN THE LOW CLOUDS SET
OVER LOWER MICHIGAN... IF I KEEP THEM IN THE TAF I WILL ONLY BE
WRONG ONLY ONCE. IF I CLEAR THEM OUT... HARD TELLING HOW OFTEN I
WILL END UP BEING WRONG. SO... GIVEN THERE IS NOT OBVIOUS
CLEARING TREND I WILL KEEP THE LOW CLOUDS IN THE FORECAST.

&&

.MARINE...
ISSUED AT 325 PM EDT TUE SEP 30 2014

WILL ALLOW THE SMALL CRAFT ADVISORY TO EXPIRE NORTH OF SOUTH HAVEN
AND ALSO CANCEL THE AREA NORTH OF PENTWATER.  BUOY DATA SHOWS WAVES
HAVE DIMINISHED TO 3-4 FEET OFFSHORE OF LUDINGTON AS WINDS ARE
SLOWLY PIVOTING TO THE NE.  PORT SHELDON AND SOUTH HAVEN BUOYS ARE
DOWN TO 2-3 FEET....WHILE BRIDGEMAN STILL SHOWS 4-5 FEET.  WILL
ALLOW THE SCA SOUTH OF SOUTH HAVEN TO EXPIRE AT 8 PM AS WINDS
CONTINUE TO DIMINISH AND TURN MORE NE.

ANOTHER PERIOD OF HIGHER WINDS AND WAVES IS EXPECTED BY THURSDAY
MORNING NORTH OF GRAND HAVEN AS SOUTH WINDS INCREASE.  THIS WILL
LIKELY EXTEND INTO THURSDAY NIGHT AND EXPAND ACROSS ALL THE
NEARSHORE WATERS AS SOUTHERLY WINDS ARE EXPECTED TO CONTINUE TO
INCREASE.

&&

.HYDROLOGY...
ISSUED AT 325 PM EDT TUE SEP 30 2014

THE RAIN FROM LATE WEDNESDAY NIGHT INTO FRIDAY IS EXPECTED TO BE
HEAVY...BUT SINCE IT WILL FALL OVER A LONG PERIOD OF TIME...HYDRO
ISSUES ARE NOT EXPECTED.  MUCH OF THE CWA SHOULD SEE BETWEEN ONE AND
TWO INCHES OF RAIN.  ONE POSSIBLE SCENARIO WOULD BE DRAINS CLOGGED
WITH LEAVES MAY RESULT IN PONDING OF WATER.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR LMZ844.

&&

$$

SYNOPSIS...JK
SHORT TERM...JK
LONG TERM...WDM
AVIATION...WDM
HYDROLOGY...JK
MARINE...JK








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