Area Forecast Discussion
Issued by NWS Grand Rapids, MI

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS63 KGRR 200317
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1117 PM EDT TUE MAY 19 2015

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 330 PM EDT TUE MAY 19 2015

A COOL AIR MASS HAS SETTLED INTO SOUTHWEST LOWER MICHIGAN AND FROST
AND FREEZING TEMPERATURES ARE A DISTINCT POSSIBILITY TONIGHT. A
FREEZE WARNING HAS BEEN POSTED FOR CENTRAL LOWER MICHIGAN AND A
FROST ADVISORY HAS BEEN HOISTED FOR THE REMAINING AREAS OF SOUTHWEST
LOWER MICHIGAN. DRY WEATHER IS EXPECTED THE REMAINDER OF THE WORK
WEEK. CONDITIONS WILL REMAIN ON THE COOL SIDE OF NORMAL THIS
WEEK...WITH A WARMUP AS WE MOVE THROUGH THE HOLIDAY WEEKEND. ALONG
WITH THE WARMER AIR WILL COME CHANCES FOR RAIN...ESPECIALLY SUNDAY
INTO MEMORIAL DAY.

&&

.SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT)
ISSUED AT 330 PM EDT TUE MAY 19 2015

MAIN FOCUS OF THE SHORT TERM WAS ON WHETHER TO EXPAND A FROST
HEADLINE INTO THE COUNTIES THAT WERE NOT COVERED BY THE FREEZE
WARNING ACROSS CENTRAL LOWER. DECIDED TO DO THAT...SO A FROST
ADVISORY IS NOW IN PLACE FOR THE REST OF THE FORECAST
AREA...ESSENTIALLY FROM INTERSTATE 96 TO THE SOUTH. DRIER AIR
CONTINUES TO POUR INTO THE AREA ON NORTHWEST WINDS...WITH THE DEW
POINT CURRENTLY AT GRAND RAPIDS AT 31 DEGREES. THINKING THE
STRATOCUMULUS WILL FADE WITH THE SETTING SUN THIS EVENING WHICH
SHOULD SET UP OK RADIATIONAL CONDITIONS. ONE ITEM OF CONCERN IS A
CORE OF WIND THAT IS SEEN IN NAM CROSS SECTIONS IN BUFKIT.
STILL...GIVEN A DECENT AMOUNT OF MAINLY CLEAR SKIES TONIGHT AND VERY
DRY/COOL AIR ALREADY IN PLACE FELT HEADLINES WERE WARRANTED ACROSS
THE FORECAST AREA.

THE REMAINDER OF THE SHORT TERM WILL BE QUIET. WE HAVE A DRY
FORECAST IN PLACE TONIGHT THROUGH THURSDAY NIGHT. THERE IS A
SHORTWAVE THAT SLIDES BY THE SOUTHERN GREAT LAKES TOMORROW NIGHT
INTO THURSDAY...BUT HAVE SIDED WITH THE DRY ECMWF AND GFS MODELS.
THE PRECIP SHOULD MISS US JUST TO THE SOUTH. ALSO ON THURSDAY...A
WEAK TROUGH MOVES THROUGH THE LOWER PENINSULA WITH SOME SPOTTY
PRECIP AMOUNTS BEING KICKED OUT BY THE MODELS. MOISTURE IS NOT ALL
THAT DEEP IN THE WED NIGHT THROUGH THURS NIGHT TIME FRAME SO AM
OPTING FOR DRY.

IT WILL BE COOL THE NEXT SEVERAL DAYS WITH NO MAJOR WARM ADVECTION
PUSH AT 850MB/S.

.LONG TERM...(FRIDAY THROUGH TUESDAY)
ISSUED AT 330 PM EDT TUE MAY 19 2015

THE MAIN FOCUS IN THE LONG TERM WILL BE THE POSSIBILITY FOR WET
WEATHER AND GUSTY WINDS GOING INTO THE HOLIDAY WEEKEND.

HIGH PRESSURE WILL BE IN CONTROL EARLY IN THE PERIOD FROM FRIDAY
THROUGH THE MAJORITY OF SATURDAY. AS HIGH PRESSURE PROGRESSES TO THE
EAST AN AREA OF LOW PRESSURE WILL BEGIN TO EJECT OUT OF THE
SOUTHWEST AND INTO THE CENTRAL PLAINS. A WARM FRONTAL BOUNDARY WILL
EXTEND OUT AHEAD OF THE SYSTEM...GIVING WAY TO SOUTHERLY INFLUENCE.
THIS SYSTEM WILL TAKE SOMEWHAT OF A SIMILAR TRACK TO LAST WEEKENDS
SYSTEM...THROUGH THE UPPER MIDWEST.

THE BEST PRECIPITATION CHANCES WILL LIKELY BE LATE SATURDAY NIGHT
INTO SUNDAY MORNING AND AGAIN MONDAY AFTERNOON AND EVENING. SATURDAY
NIGHTS RAINFALL WILL BE ASSOCIATED WITH THE RESULTING ISENTROPIC
LIFT WITH THE PASSAGE OF THE WARM FRONT. LOW PRESSURE THEN
TRANSITIONS FROM A CLOSED LOW TO A SHORT WAVE THAT IS EVENTUALLY
CONSUMED AROUND THE MAIN CYCLONIC FLOW NEAR THE HUDSON BAY. THE WARM
FRONTAL BOUNDARY GETS HINGED UP OVER CENTRAL AND NORTHERN LOWER
MICHIGAN AND BECOMES NEARLY STATIONARY. WE MAY VERY WELL SEE A LULL
IN ACTIVITY SUNDAY AFTERNOON AS WE LOSE THE LIFT.

GOING INTO MEMORIAL DAY IS WHERE WE SEE THE POSSIBILITY OF GUSTY
WINDS AND THE POTENTIAL FOR THUNDERSTORMS. WHILE UPPER LEVEL WINDS
ARE NOT SO IMPRESSIVE...AN 850MB JET CORE OF 40-50KTS MOVES OVER THE
SOUTHERN PORTIONS OF THE FORECAST AREA. THIS IS SOMETHING THAT WOULD
USUALLY TRIGGER SOME CONCERN...BUT THERE ARE A COUPLE OF LIMITING
FACTORS TO ANY REAL ORGANIZED CONVECTION. THE BEST LIFT WOULD REMAIN
NORTH ALONG THE BOUNDARY...WHILE THE BEST CAPE STAYS SOUTHEAST OF
GRAND RAPIDS. THIS MAY BE SOMETHING TO WATCH AS WE CREEP CLOSER TO
MONDAY IF CONDITIONS BECOME BETTER ORGANIZED. OTHERWISE...IT SEEMS
THE HOLIDAY WILL HAVE SCATTERED AFTERNOON THUNDERSTORMS...SOME
LOCALIZED HEAVY RAINFALL AND GUSTY WINDS.

&&

.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 805 PM EDT TUE MAY 19 2015

THE WIND WILL GRADUALLY DECREASE THROUGH THE REMAINDER OF THE
EVENING. AS A RESULT THE WAVES WILL SLOWLY DIMINISH...WITH VALUES
EXPECTED TO REMAIN UNDER SMALL CRAFT ADVISORY CRITERIA.


&&

.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 WEDNESDAY FOR MIZ050-056>059-
     064>067-071>074.

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

LM...NONE.
&&

$$

SYNOPSIS...DUKE
SHORT TERM...DUKE
LONG TERM...JAM
AVIATION...MJS
HYDROLOGY...EBW/CAS
MARINE...MJS


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.