Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 271926
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
326 PM EDT WED APR 27 2016

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

.SYNOPSIS...
ISSUED AT 326 PM EDT WED APR 27 2016

RAIN SHOULD OVERSPREAD THE AREA AFTER MIDNIGHT FROM SOUTH TO
NORTH AS ANOTHER STORM SYSTEM FROM THE SOUTHERN PLAINS TRACKS JUST
SOUTH OF MICHIGAN THURSDAY. THERE IS A RISK OF AN ISOLATED
THUNDERSTORM THURSDAY SOUTH OF INTERSTATE 96. THE RAINFALL WILL BE
HEAVIEST NEAR AND SOUTH OF INTERSTATE 96. IT WILL BE CHILLY
THURSDAY WITH TEMPERATURES ONLY IN THE 40S. CANADIAN HIGH PRESSURE
WILL BRING DRY AND COOL WEATHER FOR LATER FRIDAY INTO SATURDAY
BEFORE YET ANOTHER PACIFIC STORM MOVES INTO THE AREA WITH MORE
RAIN POSSIBLE SATURDAY NIGHT INTO SUNDAY.

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT)
ISSUED AT 326 PM EDT WED APR 27 2016

THE MAIN QUESTION FOR THIS FORECAST IS HOW MUCH OF THE RAIN FROM
THE SOUTHERN PLAINS SYSTEM MAKES IT INTO MICHIGAN LATER TONIGHT
INTO FRIDAY MORNING. THERE IS A SMALL CHANCE OF ISOLATED
THUNDERSTORMS SOUTH OF INTERSTATE 96 THURSDAY TOO.

THE SURFACE LOW ASSOICATED WITH THE SYSTEM THAT CAUSED ALL THE
SEVERE WEATHER OVER THE SOUTHERN PLAINS YESTERDAY WILL TRACK JUST
SOUTH OF THE AREA THURSDAY. THIS TRACK IN THE WINTER WOULD MEAN
SNOW HERE. SINCE ITS LATE APRIL...WE WILL SEE A COLD RAIN INSTEAD
WITH GUSTY EAST WINDS.

THE MAIN ISSUE IS JUST HOW FAR NORTH THE CONVECTIVELY CREATED
SHORTWAVE OVER THE SOUTHERN PLAINS GETS THURSDAY. SOUTHWEST
MICHIGAN GETS AN ISENTROPIC LIFT (WARM ADVECTION LIFT) EVENT FROM
THIS SYSTEM THURSDAY. IT IS POSSIBLE MOST OF THE ENERGY FOR THIS
WILL ACTUALLY TRACK SOUTH OF THE MICHIGAN BOARDER KEEPING MOST OF
THE RAIN DOWN THERE. EVEN SO...WHAT REMAINS OF THE SHEARING OUT
UPPER LOW WILL TRACK BETWEEN INTERSTATE 94 AND INTERSTATE 96
DURING THE DAY TIME HOURS OF THURSDAY. SEEMS TO ME WITH A TRACK
THAT FAR NORTH...WE SHOULD SEE SOME RAIN FROM THIS SYSTEM. SO I
HAVE LIKELY POPS FOR THE DAY TIME HOURS OF THURSDAY.

I KEEP THE ISOLATED THUNDERSTORMS IN THE FORECAST DUE TO SOME WEAK
ELEVATED CAPE BUT I COULD SEE ALL OF THE STORMS STAYING SOUTH OF
THE AREA SINCE THE LOW LEVEL JET IS NOT AMID THIS WAY...NOR IS THE
MOISTURE TRANSPORT VECTORS IN THE 1000/850 LAYER.

BEYOND THAT THE SYSTEM SLOWLY SHEARS OUT... SO THE LIGHT
RAIN/DRIZZLE WILL LINGER INTO FRIDAY BEFORE ENDING. WE SHOULD SEE
SOME CLEARING LATER FRIDAY. MORE THAN ANYTHING IT WILL BE CHILLY
FOR THIS TIME OF YEAR THROUGH FRIDAY NIGHT.

$$


.LONG TERM...(SATURDAY THROUGH WEDNESDAY)
ISSUED AT 326 PM EDT WED APR 27 2016

WE ARE LOOKING AT TWO PERIODS OF RAIN CHCS OVER THE COURSE OF THE
LONG TERM. THE FIRST ONE WILL BE OVER THE WEEKEND...WITH THE SECOND
PERIOD COMING TOWARD THE END OF THE PERIOD ON TUE NIGHT AND WED.

THE LATEST TRENDS SHOW THAT RAIN SHOWERS WILL BE ON THE INCREASE ON
SATURDAY. THE EXACT TIMING IS STILL A BIT UNCERTAIN...BUT WE WILL
HAVE A DRY ERLY FLOW THAT SHOULD DIMINISH SOME OF THE INITIAL SHOWER
ACTIVITY. UNCERTAINTY ALSO REMAINS WITH REGARD TO HOW FAR NORTH THIS
SYSTEM AND THE RAIN COMES. THE MODELS HAVE GENERALLY TRENDED A
LITTLE FURTHER NORTH. THE CHC OF RAIN REMAINS THROUGH SUN AS THE
UPPER LOW OPENS UP...AND WE REMAIN NEAR THE DEFORMATION ZONE UNTIL
IT MOVES EAST. WE HAVE THE HIGHEST RAIN CHCS ACROSS THE SOUTH...
GRADUALLY DIMINISHING TOWARD THE NORTH.

WE WILL SEE A BREAK IN THE RAIN CHCS THEN FROM MOST OF MON INTO TUE.
SHORT WAVE RIDGING WILL BUILD IN AND WILL SUPPRESS RAIN CHCS FOR A
SHORT PERIOD.

RAIN SHOWER CHANCES WILL THEN INCREASE AGAIN HEADING TOWARD MID-WEEK
NEXT WEEK. THE UPPER AIR PATTERN WILL SEE A BIT OF A SHIFT AS THE
RIDGE AXIS CURRENTLY JUST OFF OF THE WRN U.S. COAST WILL SHIFT EAST
A BIT BY MID-WEEK. IT WILL STRENGTHEN...ALLOWING HEIGHTS TO FALL
FAIRLY WELL FOR THE ERN PORTION OF THE COUNTRY AS ENERGY DIVES SE
OUT OF CANADA. THIS COULD END UP CARVING OUT AN UPPER LOW AND BRING
COOL AND SHOWERY WEATHER TO THE AREA. THE DETAILS REMAIN
SKETCHY...BUT ALL OF THE GLOBAL ENSEMBLES SHOW UPPER TROUGHING
TAKING SHAPE OVER THIS PORTION OF THE COUNTRY.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 143 PM EDT WED APR 27 2016

NO IMPACTS FOR AVIATION INTERESTS FOR THE FIRST HALF OF THE FCST
PERIOD...WITH SOME MVFR POSSIBLE ACROSS THE SOUTH FOR THE LATTER
HALF OF THE PERIOD.

STRATUS FROM EARLIER HAS SHIFTED SOUTH AND WEST OF THE AREA WITH
THE DRY ERLY FLOW IN FIRM CONTROL THIS AFTERNOON. HIGH CLOUDS ARE
INCREASING THIS AFTERNOON...BUT SHOULD NOT BE AN ISSUE.

WE WILL SEE SOME SHOWER ACTIVITY TRY TO MOVE IN AFTER SUNSET
TONIGHT. THIS WILL BE EATEN UP BY THE DRY FLOW EXPECTED TO REMAIN
IN PLACE. EVENTUALLY SOME RAIN WILL BECOME MORE LIKELY...ESPECIALLY
FURTHER SOUTH TOWARD SUNRISE ON THU. WE EXPECT MVFR CIGS TO
DEVELOP/MOVE IN AROUND 12Z OR SO ALONG I-94 AND REMAIN THROUGH THE
END OF THE FCST PERIOD. CONDITIONS ALONG THE I-96 TERMINALS WILL
LIKELY REMAIN VFR WITH VERY LIGHT RAIN SHOWERS.


&&

.MARINE...
ISSUED AT 326 PM EDT WED APR 27 2016

WINDS AND WAVES WILL REMAIN BELOW SMALL CRAFT ADVISORY CRITERIA
THROUGH SATURDAY.

&&

.HYDROLOGY...
ISSUED AT 1255 PM EDT WED APR 27 2016

RECENT RAINFALL HAS RESULTED IN MINOR RISES ON STREAMS. SIGNIFICANT
RISES ON MAIN STEM RIVERS ARE NOT LIKELY GIVEN THE QUICK HITTING
NATURE OF THIS SYSTEM. ADDITIONAL RAINFALL TONIGHT INTO THURSDAY
WILL ACT TO KEEP SMALLER STREAMS AND RIVERS ELEVATED... WITH A
SMALLER CHANCE FOR ELEVATED MAIN STEM RIVERS. FLOODING IS NOT
EXPECTED AT THIS TIME.

&&

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

$$

SYNOPSIS...WDM
SHORT TERM...WDM
LONG TERM...NJJ
AVIATION...NJJ
HYDROLOGY...63
MARINE...WDM


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