Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 031930
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
330 PM EDT SUN MAY 3 2015

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

.SYNOPSIS...
ISSUED AT 330 PM EDT SUN MAY 3 2015

A COLD FRONT WILL BRING SOME SHOWERS AND THUNDERSTORMS TONIGHT.
THE FRONT WILL STALL JUST SOUTH OF LOWER MICHIGAN ON MONDAY AND
BRING CHANCES FOR RAIN AT TIMES THROUGH NEXT WEEKEND.

&&

.SHORT TERM...(THIS EVENING THROUGH TUESDAY NIGHT)
ISSUED AT 330 PM EDT SUN MAY 3 2015

TIMING AND COVERAGE OF PRECIP WILL BE THE FORECAST ISSUE IN THE
NEAR TERM. GOOD MOISTURE TRANSPORT AND A 35 TO 40 KT LLJ ARRIVES
AHEAD OF APPROACHING COLD FRONT. THERE IS ALSO ENOUGH MID LEVEL
INSTABILITY FOR SOME THUNDER TO BE EMBEDDED IN THE AREA OF RAIN.

SHOWERS NOW OVER NORTHERN ILLINOIS WILL SPREAD EAST AND ARRIVE ACROSS
THE WESTERN FORECAST FORECAST AREA THIS EVENING AND SLOWLY
PROGRESSES EASTWARD...NOT REACHING THE EXTREME SE CWA UNTIL AROUND
12Z ON MONDAY. GOOD FORECAST CONSISTENCY IN THE MODELS LEADS TO
ABOVE AVERAGE CONFIDENCE IN THE FORECAST OF THE FRONT SLOWING
DURING MONDAY AND EVENTUALLY STALLING OUT JUST SOUTH OF THE
FORECAST AREA. OVERRUNNING CONTINUES ACROSS THE SOUTHERN FORECAST
AREA THROUGH MONDAY NIGHT WITH LIKELY POPS ACROSS THE SOUTH
DECREASING TO CHANCE ACROSS THE CENTRAL FORECAST AREA AND SLIGHT
CHANCE OR NO POPS ACROSS THE NORTH.

THE FRONT REMAINS ACTIVE ON TUESDAY WITH CONVECTION RIDING ALONG
IT AND THEN SLOWLY LIFTS NORTH ON TUESDAY NIGHT. FORECAST SOUNDINGS
CONTINUE TO SHOW THUNDER POTENTIAL ACROSS THE SOUTHERN HALF OF THE
FORECAST AREA DURING MOST OF TUESDAY AND TUESDAY NIGHT.


.LONG TERM...(WEDNESDAY THROUGH SUNDAY)
ISSUED AT 318 PM EDT SUN MAY 3 2015

ABOVE TO MUCH ABOVE NORMAL TEMPERATURES ARE EXPECTED WEDNESDAY
THROUGH SATURDAY DUE TO PERSISTENT SOUTH TO SOUTHWESTERLY FLOW WARM
AIR ADVECTION. HIGH TEMPERATURES SHOULD REACH THE 75 TO 80 DEGREE
RANGE IN THAT TIME FRAME.

THE PERSISTENT SOUTH TO SW FLOW WILL RESULT IN INCREASING MOISTURE.
INSTABILITY MID TO LATE WEEK WILL GENERALLY BE FAIRLY WEAK BUT
SUFFICIENT ENOUGH FOR THE DEVELOPMENT OF A SCATTERED SHOWER OR STORM
AT JUST ABOUT ANY TIME WEDNESDAY THROUGH SATURDAY. HOWEVER
PROBABILITIES FOR A SHOWER OR STORM ARE QUITE LOW WEDNESDAY AND
THURSDAY DUE TO THE LACK OF A TRIGGERING MECHANISM FOR CONVECTIVE
INITIATION TO OCCUR AND WEAK INSTABILITY.

THE RELATIVELY BETTER CHANCE FOR SCATTERED SHOWERS AND TSTORMS WILL
COME FRIDAY INTO SATURDAY WHEN INSTABILITY WILL BE RELATIVELY
STRONGER (POTENTIALLY AROUND 1000-1500 J/KG OF SB CAPE). THIS IN
CONJUNCTION WITH DEW POINT VALUES WELL INTO THE 50S AND A FORCING
MECHANISM COMING FROM THE APPROACHING LOW PRESSURE AND WEAK COLD
FRONT FROM THE WEST. THAT BOUNDARY WILL LIKELY STALL OUT IN OUR
REGION RESULTING IN CONTINUED POTENTIAL FOR SCATTERED SHOWERS AND
STORMS THROUGH NEXT WEEKEND.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY)
ISSUED AT 1230 PM EDT SUN MAY 3 2015

VFR CONDITIONS WILL CONTINUE THIS AFTERNOON BUT IT WILL BE BREEZY
WITH SW WIND GUSTS TO NEAR 25 KTS AND GRADUALLY INCREASING MID LEVEL
CLOUD COVER. SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS WILL
DEVELOP MAINLY AFTER MIDNIGHT. CONDITIONS WILL GRADUALLY DETERIORATE
TO MVFR VERY LATE TONIGHT THROUGH MIDDAY MONDAY.

BRIEF REDUCTIONS TO IFR CONDITIONS ARE POSSIBLE DURING THE EARLY
MORNING HOURS MONDAY THROUGH 18Z MONDAY IN HEAVIER SHOWERS AND
ISOLATED STORMS. PRIMARILY MVFR CONDITIONS WILL CONTINUE INTO MONDAY
AFTERNOON DUE TO EXTENSIVE LOW CLOUD COVER AND LINGERING SHOWERS AND
ISOLATED STORMS. THE BETTER CHANCE FOR THUNDERSTORMS MONDAY
AFTERNOON WILL BE SOUTH OF THE I-94 CORRIDOR ACROSS NORTHERN
INDIANA/OHIO.


&&

.MARINE...
ISSUED AT 318 PM EDT SUN MAY 3 2015

SHOWERS AND THUNDERSTORMS EXPECTED TONIGHT AND INTO EARLY NEXT
WEEK WITH WINDS AND WAVES REMAINING BLO SMALL CRAFT ADVISORY.

&&

.HYDROLOGY...
ISSUED AT 1136 AM EDT SUN MAY 3 2015

RIVERS ARE RUNNING WELL WITHIN BANKS AND REMAIN STEADY...IF NOT
FALLING EVER-SO-SLIGHTLY. THOUGH FLOODING IS NOT ANTICIPATED AT
THIS TIME...THE PATTERN BECOMES ACTIVE OVER THE COURSE OF THE
UPCOMING WEEK AND WE MAY SEE WITHIN BANK RISES.

PRECIPITATION IS EXPECTED TO DEVELOPED AND PROGRESS FROM NORTH TO
SOUTH BEGINNING LATE TONIGHT. THE FRONTAL BOUNDARY RESPONSIBLE FOR
THE PRECIPITATION WILL STALL NEAR THE SOUTHERN LOWER MICHIGAN
BORDER WHICH WILL LEAD TO SOME OF THE HIGHER TOTALS ALIGNING ALONG
AND SOUTH OF I-94. THIS FRONT THEN RETURNS NORTH NEAR MIDWEEK AND
PROVIDES ANOTHER DECENT SHOT AT PRECIPITATION FOR CENTRAL LOWER
MICHIGAN DURING THAT TIME FRAME. YET ANOTHER ROUND OF WET WEATHER
IS POISED TO MOVE THROUGH LATE IN THE WEEK AND INTO NEXT WEEKEND.

THE MAIN IMPACTS WOULD LIKELY BE MINOR AND NOT REALLY FELT UNTIL WE
GET INTO THE NEW WORK WEEK. LOCATIONS THAT ARE ALREADY RAIN SOAKED
AND RECEIVE ANY ADDITIONAL CONVECTIVE PRECIPITATION COULD SEE
MINOR PONDING ON ROADWAYS...OR LOW LYING AREAS THAT ARE TYPICALLY
AFFECTED BY HEAVIER RAIN. AN ADDITIONAL NOTE IS THAT WE ARE DRY NOW
AND GREEN-UP IS OCCURRING IN MANY LOCATIONS. THIS WILL DEFINITELY
HELP IN TAKING UP A LOT OF THE MOISTURE THAT FALLS.

&&

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

$$

SYNOPSIS...OSTUNO
SHORT TERM...OSTUNO
LONG TERM...OSTUNO/LAURENS
AVIATION...LAURENS
HYDROLOGY...JAM
MARINE...OSTUNO



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