Area Forecast Discussion
Issued by NWS Grand Rapids, MI

Home | Current Version | Previous Version | Graphics & Text | 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 061701
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
ISSUED BY NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
101 PM EDT WED MAY 6 2015

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 328 AM EDT WED MAY 6 2015

A STATIONARY FRONT OVER CENTRAL INDIANA WILL MOVE NORTH TODAY ACROSS
LOWER MICHIGAN. TEMPERATURES WILL CLIMB INTO THE 70S THIS AFTERNOON
AND BE EVEN WARMER THURSDAY WHEN HIGHS REACH THE LOWER 80S. THE BEST
CHANCE OF THUNDERSTORMS COMES FRIDAY WHEN A COLD FRONT WILL APPROACH
FROM THE WEST. SHOWERS AND THUNDERSTORMS WILL REMAIN IN THE FORECAST
THROUGH THE WEEKEND AS THAT FRONTAL BOUNDARY WILL GET HUNG UP OVER
LOWER MICHIGAN.

&&

.UPDATE...
ISSUED AT 739 AM EDT WED MAY 6 2015

AN AREA OF FOG...LOCALLY DENSE CONTINUES TO SPREAD SLOWLY
NORTHWARD THIS MORNING FROM THE INTESTATE 94 AREA TOWARD THE
INTESTATE 96 AREA. I BELIEVE THE FOG WILL MIX OUT BY MID MORNING
SO I WILL NOT ISSUE A FOG ADVISORY BUT THIS WILL NEED TO BE
WATCHED IF IT DOES NOT MIX OUT AS QUICK AS I AM THINKING IT WILL.
I DID UPDATE THE GRIDS AND ZONES TO PUT AREAS OF DENSE FOG TILL
MID MORNING.

&&

.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 328 AM EDT WED MAY 6 2015

FORECAST CONCERNS DEAL WITH PCPN TRENDS THROUGH THE PERIOD. THE
UPPER RIDGE AXIS WILL REMAIN OVERHEAD TODAY AS IT MOVES FROM THE
PLAINS TO THE EASTERN US. THE RIDGE COUPLED WITH LITTLE IN THE WAY
OF MOISTURE TRANSPORT MEANS THAT PCPN CHANCES WON/T BE VERY HIGH.
KGRR-88D CURRENTLY SHOWS SOME WEAK SHOWERS OVER LAKE MICHIGAN BUT
THE TREND HAS BEEN A DIMINISHING ON DURING THE PAST SEVERAL HOURS. A
STATIONARY FRONT WILL MOVE NORTH THROUGH THE CWA TODAY. WE/LL KEEP A
SLIGHT CHANCE OF A SHOWER FOR THIS FEATURE BUT NOT MUCH MORE.
THERE/S A LITTLE CAPE BUT NOT MUCH INSTABILITY TODAY. TONIGHT AND
THURSDAY LOOK DRY AND MILD WITH TEMPS TOPPING 80 THURSDAY. THE
BETTER CHANCE OF RAIN COMES FRIDAY AS A STRONGER SW FLOW DEVELOPS ON
THE BACK SIDE OF THE RIDGE. A COLD FRONT WILL MOVE TO WISCONSIN
FRIDAY. THIS SHOULD BE CLOSE ENOUGH TO SEE HIGHER CHANCES OF SHOWERS
AND THUNDERSTORMS. MOISTURE TRANSPORT VECTORS ARE MUCH LARGER FRIDAY
AFTERNOON AND SO IS THE INSTABILITY. LI/S FALL TO -6C AS MLCAPE
CLIMBS TO AROUND 1K J/KG. SHEAR VALUES ARE VERY LOW SO SVR STORMS
NOT EXPECTED FRIDAY.

.LONG TERM...(FRIDAY NIGHT THROUGH TUESDAY)
ISSUED AT 328 AM EDT WED MAY 6 2015

IT WOULD SEEM A CHANGE TO COOLER TEMPERATURES IS LIKELY BY THE END
OF THIS FORECAST PERIOD. TILL THEN THROUGH TEMPERATURE WILL CONTINUE
TO RUN ABOVE NORMAL THROUGH THE WEEKEND...INCLUDING MONDAY OF NEXT
WEEK.

THIS COULD BE A STORMY PERIOD AS THE PRIMARY FRONTAL SYSTEM STALLS
NEAR US ON SATURDAY AND REMAINS IN PLACE INTO MONDAY BEFORE THE MAIN
SYSTEM COMES THROUGH.  THIS WOULD MEAN THUNDERSTORMS ARE POSSIBLE
EACH DAY BUT THE GREATEST CHANCE OF STRONG TO SEVERE STORMS WOULD
SEEM TO BE MONDAY AS THE MAIN SYSTEM COMES THROUGH THE AREA.

CURRENTLY WE HAVE AN UPPER RIDGE OVER THE EASTERN UNITED STATES WITH
A CLOSED COLD CORE UPPER LOW OVER HUDSON BAY CREATING CONFLUENT FLOW
OVER MICHIGAN. BY FRIDAY EVENING... THE UPPER LOW OVER THE SOUTHWEST
UNITED STATES STARTS TO GET SHEARED OUT BY THE NEXT UPSTREAM PACIFIC
SYSTEM. JUST HOW FAR NORTH THE SURFACE SYSTEM WITH THAT GETS
RELATIVE TO MICHIGAN MONDAY DETERMINES IF WE GET STRONG STORMS AND
WARM AIR MONDAY (ECMWF) OR IF IT TURNS OUT MORE LIKE YESTERDAY WITH
MICHIGAN IN THE COLD AIR (GFS SOLUTION).  GIVEN THE STRENGTH OF THE
SYSTEM NOW...I AM FAVORING THE ECMWF. SO I AM THINKING STRONG STORMS
ARE POSSIBLE MONDAY. AFTER THAT THE COLD AIR COMES BACK IN FOR
AWHILE.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 101 PM EDT WED MAY 6 2015

LINGERING LOW CLOUDS AND FOG WILL CONTINUE TO RAPIDLY DIMINISH OVER
THE NEXT HOUR UNDER DAYTIME HEATING. STRONG HEATING WILL DEEPEN THE
BOUNDARY LAYER DURING THE AFTERNOON WHICH WILL HOLD BASES ASSOCIATED
WITH ANY DIURNALLY DRIVEN CLOUDS ABOVE 6K FT. GOOD RADIATIONAL
COOLING TONIGHT AND RESIDUAL SFC MOISTURE WILL POSE THE RISK FOR
SOME FOG DEVELOPMENT LATE. THE GRADIENT FLOW WILL BE A BIG LIMITING
FACTOR AND WILL ONLY WARRANT FCST VISIBILITIES INTO THE 2-5SM
RANGE...WITH THE POTENTIAL FOR MORE WIDESPREAD FOG OVER ERN LOWER MI
WHERE THE GRADIENT WILL BE MUCH WEAKER.

&&

.MARINE...
ISSUED AT 328 AM EDT WED MAY 6 2015

SOME FOG IS POSSIBLE OVER THE LAKE TODAY...OTHERWISE NO HAZARDS ARE
EXPECTED.


&&

.HYDROLOGY...
ISSUED AT 1149 AM EDT TUE MAY 5 2015

TODAYS PRECIPITATION IS IN THE IMMEDIATE SCOPE OF ATTENTION WHILE
THE NEXT BIG CHALLENGE IS KEYING IN ON NEXT WEEKENDS RAIN
POTENTIAL. ANY RIVER CONCERNS WOULD BE IN THE LATE WEEK AND
WEEKEND TIMEFRAME.

PRECIPITATION MATERIALIZED FAIRLY WELL THIS MORNING WHICH IS
PROVIDING
SOME NEEDED RELIEF TO AREAS RECENTLY CONSIDERED ABNORMALLY DRY.
ADDITIONAL RAINFALL IS POSSIBLE THROUGH THE AFTERNOON WITH LOCALIZED
MODERATE TO HEAVY RAINFALL. LOCATIONS ALONG AND SOUTH OF I-94 HAVE
THE GREATEST CHANCE FOR SEEING CONVECTIVE TYPE RAINFALL...BUT LOWER
INSTABILITY WOULD LIMIT THE THREAT.

THE FORECAST GETS A BIT TRICKY GOING INTO LATE WEEK AND NEXT WEEKEND.
A SYSTEM WILL DEVELOP OUT OVER THE PLAINS AND IS EXPECTED TO
TRAVEL NORTH AND EAST. THE GULF OF MEXICO OPENS UP TO ALLOW FOR
ABUNDANT MOISTURE TO FEED NORTHWARD AS WELL. MEANWHILE...THE
SYSTEM OVER THE SOUTHEAST OFF THE CAROLINA COAST COULD PLAY A PART
IN HOW THE PATTERN RESPONDS. INLAND MOTION OF THE SOUTHEAST SYSTEM
COULD AID IN DRAPING A STATIONARY BOUNDARY THROUGH THE OHIO VALLEY
OR SOMEWHERE THROUGH THE MIDWEST. THE RESULT COULD VERY WELL END
UP BEING PERIODS OF RAINFALL...POSSIBLY HEAVY...SPANNING FROM
LATE FRIDAY ON THROUGH MONDAY. THIS IS SOMETHING THAT BARES
WATCHING AS WE HEAD INTO THURSDAY AND FRIDAY. IF THE SCENARIO WERE
TO PLAY OUT THE BIGGEST CONCERN WOULD THEN BECOME MULTIPLE ROUNDS
OF HEAVIER RAIN. THOUGH RIVERS AND STREAMS ARE WELL WITHIN
BANKS...FORECASTS WILL BE MONITORED FOR THIS POTENTIAL.

&&

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

$$

UPDATE...WDM
SYNOPSIS...04
SHORT TERM...04
LONG TERM...WDM
AVIATION...SC
HYDROLOGY...JAM
MARINE...04



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