Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 011114
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
714 AM EDT FRI MAY 1 2015

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 321 AM EDT FRI MAY 1 2015

PLEASANT AND MILD WEATHER WILL BE IN STORE FOR TODAY INTO THE
WEEKEND.  TEMPERATURES WILL MAINLY BE IN THE UPPER 60S TODAY...AND
WARM INTO THE MID 70S BY SUNDAY...HOWEVER IT WILL BE COOLER NEAR THE
LAKE EACH DAY.

SHOWERS AND THUNDERSTORMS ARE EXPECTED TO ARRIVE SUNDAY NIGHT AND
ARE EXPECTED TO LINGER INTO AT LEAST TUESDAY.  ANTICIPATE
TEMPERATURES TO COOL INTO THE 60S.

&&

.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 321 AM EDT FRI MAY 1 2015

NOT TOO MANY ISSUES THROUGH THE SHORT TERM.  WE WILL SEE A GRADUALLY
WARMING TREND...HOWEVER I/M BIT CONCERNED WE MAY SEE A FEW SHOWERS
IN THE WARM ADVECTION PATTERN SATURDAY NIGHT/SUNDAY MORNING.

SURFACE HIGH PRESSURE WILL SLOWLY BUILD INTO THE REGION TODAY AND
TONIGHT RESULTING IN MOSTLY CLEAR AND COMFORTABLE WEATHER.  HOWEVER
ONCE WE GET ON THE BACKSIDE OF THIS HIGH WE SHOULD BEGIN TO SEE SOME
WARM ADVECTION MID CLOUDS FOR SATURDAY.  ADDED A BIT MORE CLOUDS TO
THE FORECAST.  STILL...DO NOT BELIEVE THESE CLOUDS WILL IMPEDE US
FROM GETTING TEMPS TOWARD THE 70 DEGREE MARK.

MOISTURE DEPTH INCREASES OVERNIGHT SATURDAY NIGHT...ESPECIALLY NORTH
AS THE WARM ADVECTION CONTINUES.  ADDED THE LOW CHC FOR A FEW LIGHT
SHOWERS MAINLY ALONG THE HIGHWAY 10 REGION LATE SATURDAY NIGHT.
THERE MAY ALSO BE SOME DWINDLING CONVECTION COMING ACROSS LAKE
MICHIGAN...FROM A COLD FRONT ENTERING THE WESTERN GREAT LAKES SUNDAY
MORNING.  ADDED A LOW CHANCE OF DYING SHOWERS ENTERING THE
LAKESHORE.  A WARM FRONT SHARPENS ACROSS NORTHERN LOWER INTO SUNDAY
AFTERNOON.  THIS WILL PUT US SOLIDLY IN THE WARM SECTOR AND ANY
SHOWERS AND CLOUDS SHOULD GRADUALLY DISSIPATE TOWARD MID DAY.  MUCH
OF THE AREA SHOULD REACH THE MID 70S AWAY FROM THE LAKESHORE.

.LONG TERM...(SUNDAY NIGHT THROUGH THURSDAY)
ISSUED AT 321 AM EDT FRI MAY 1 2015

WE CONTINUE TO FOCUS ON THE RISK FOR SHOWERS AND THUNDERSTORMS
SUNDAY NIGHT THROUGH WEDNESDAY...WITH GENERALLY NON-SEVERE ACTIVITY
EXPECTED WITH THE GREATEST RAINFALL AMOUNTS LIKELY TO OCCUR ACROSS
FAR SOUTHERN LOWER MICHIGAN AND NORTHERN INDIANA WITH THIS EVENT.

OVERALL...00Z MODEL TRENDS POINT TOWARD A DECAYING BATCH OF
THUNDERSTORMS MOVING OVER LAKE MICHIGAN SUNDAY NIGHT AS MODEST PVA
OCCURS AND A 30-35 KNOT LLJ MOVES INTO THE AREA. WHICHEVER MODEL YOU
LOOK AT (FIM/GFS/ECMWF/GEM)...THE SCENARIO IS THE SAME IN REGARD TO
MUCH HIGHER MODEL QPF ACROSS IOWA/WISCONSIN/ILLINOIS SUNDAY NIGHT.
THIS PRECIP WILL BE IN ASSOCIATION WITH A WEAK COLD FRONT THAT MOVES
THROUGH THE REGION...EVENTUALLY STALLING OUT AS A STATIONARY FRONT
ACROSS NORTHERN IL AND IN MONDAY NIGHT. THIS BOUNDARY WILL SERVE AS
A FOCAL POINT FOR ADDITIONAL SHOWER/T-STORM ACTIVITY THROUGH TUESDAY
NIGHT.

THE 00Z ECWMF IS FAR LESS BULLISH ON PRECIP ALONG THE STATIONARY
BOUNDARY IN THE MIDST OF WEAK H850 MOISTURE CONVERGENCE HEADING FROM
THE GULF INTO THE BOUNDARY. THE GFS AND GEM HAVE STRONGER LOW
LEVEL JETS AND HIGHER MODEL QPF ACROSS NORTHERN IL/SOUTHERN
MI/NORTHERN IN. A CONSENSUS MODEL BLEND OF WHERE THE BOUNDARY STALLS
SUGGESTS A FURTHER SOUTH SCENARIO AT THIS TIME...MEANING THE I-94
REGION AND POINTS SOUTH HAVE THE BEST CHANCE AT SEEING ADDITIONAL
ROUNDS OF SHOWERS/STORMS MONDAY NIGHT INTO TUESDAY NIGHT. THIS BEING
SAID...THE LOCATION OF THE BOUNDARY WILL LIKELY FLUCTUATE A BIT SO
WE ARE HOLDING POPS AT LIKELY FOR THE SOUTHERN CWA AT THIS TIME.
INSTABILITY LOOKS MARGINAL WITH THIS EVENT ALTHOUGH DEEP LAYER SHEAR
COULD BE DECENT ON TUESDAY. HOWEVER...MOST OF THE CWA COULD BE NORTH
OF THE BOUNDARY AT THAT TIME...SO RIGHT NOW THERE SEEMS TO BE A LOW
THREAT FOR ANY SEVERE WEATHER.

THE POTENTIAL EXISTS FOR AN INCH OR MORE OF RAINFALL SOUTH OF I-96
FROM SUNDAY NIGHT THROUGH WEDNESDAY MORNING...WITH HIGHER AMOUNTS IN
THUNDERSTORMS. THE HEAVY RAINFALL THREAT WOULD BE GREATER IF NOT FOR
THE UNIMPRESSIVE H1000-H850 MOISTURE FLUX CONV OCCURRING NEAR THE
BOUNDARY MONDAY AND TUESDAY. AS A RESULT...EXCESSIVE AMOUNTS OF RAIN
ARE NOT ANTICIPATED.

GOOD MODEL AGREEMENT ON PUSHING THE BOUNDARY THROUGH AS A WARM FRONT
WEDNESDAY AND THURSDAY WITH WARMING TEMPS NEAR CERTAIN. HIGHS WELL
INTO THE 70S AND POSSIBLY NEAR 80 ON THURSDAY WITH DEEP MIXING AND
H850 TEMPS BETWEEN 12-13C.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 713 AM EDT FRI MAY 1 2015

VFR CONDITIONS. LIGHT LAKE BREEZE EXPECTED AT MKG THIS AFTERNOON
AND IT COULD REACH GRR AS WELL. OTHER THAN THIS...VERY QUIET DAY.

&&

.MARINE...
ISSUED AT 321 AM EDT FRI MAY 1 2015

ALLOWED THE SMALL CRAFT ADVISORY TO EXPIRE SOUTH OF GRAND HAVEN THIS
MORNING AS NORTHERLY WINDS CONTINUE TO DIMINISH.

THE LAKE SHOULD REMAIN RATHER CALM THROUGH THE WEEKEND TOO WITH HIGH
PRESSURE BUILDING IN.  SOUTH SOUTHWEST WINDS WILL PICK UP OVER THE
WEEKEND TO 10 TO 20 KNOTS. BUT GIVEN THE CHILLY LAKE THESE WARMER
WINDS WILL BE A STABLE REGIME AND WILL NOT STIR UP THE LAKE TOO
MUCH.  LAKE TEMPS ARE ONLY IN THE UPPER 30S HOWEVER...SO ANYONE
VENTURING OUT SHOULD USE EXTRA CAUTION.


&&

.HYDROLOGY...
ISSUED AT 139 PM EDT THU APR 30 2015

RIVERS ARE RUNNING NEAR TO BELOW NORMAL. NO ISSUES ARE EXPECTED
THROUGH THE WEEKEND. WE ARE MONITORING THE POTENTIAL FOR OVER AN
INCH OF RAINFALL DURING THE FIRST HALF OF NEXT WEEK. CONFIDENCE IS
CURRENTLY NOT HIGH ON WHERE THE AXIS OF HEAVIEST RAIN WILL BE. WITH
THE GREEN-UP UNDERWAY... PLANTS AND SOIL ARE ABLE TO ABSORB A
GREATER AMOUNT OF RAIN THAN EARLIER IN THE SPRING. THIS WILL BUFFER
RIVER RESPONSE TO SOME EXTENT.

&&

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

$$

SYNOPSIS...JK
SHORT TERM...JK
LONG TERM...HOVING
AVIATION...HOVING
HYDROLOGY...CAS
MARINE...JK





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