Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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000
FXUS63 KGRR 191718
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
118 PM EDT Sun Mar 19 2017

LATEST UPDATE...
Aviation

.SYNOPSIS...
ISSUED AT 330 AM EDT SUN MAR 19 2017

SUNDAY WILL START OFF RATHER CLOUDY, BUT PARTLY SUNNY SKIES ARE
EXPECTED INTO THE AFTERNOON.  HIGH TEMPERATURES WILL BE 40 TO 45. A
CHANCE OF RAIN SHOWERS WILL MOVE IN TONIGHT, WITH THE BEST CHANCE OF
RAIN COMING LATE TONIGHT INTO MONDAY MORNING.  A RUMBLE OF THUNDER
WILL ALSO BE POSSIBLE SOUTH OF I-96.  THE RAIN WILL MOVE OUT OF THE
REGION MONDAY AFTERNOON INTO THE EARLY EVENING.  MONDAY NIGHT AND
TUESDAY LOOK TO BE DRY, WITH SOME PARTIAL CLEARING.

MUCH OF THE MID WEEK PERIOD APPEARS TO BE DRY, WITH THE NEXT CHANCE
OF RAIN COMING THURSDAY NIGHT THROUGH FRIDAY NIGHT.

&&

.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 330 AM EDT SUN MAR 19 2017

SOME PARTIAL CLEARING IS EXPECTED TODAY, BUT THEN WE WILL SEE RAIN
SHOWERS RETURN TONIGHT INTO MONDAY.  TEMPERATURES WILL TREND A BIT
WARMER COMPARED TO RECENT DAYS.

SATELLITE TRENDS CONTINUE TO SHOW CLOUD COVER ACROSS THE REGION THIS
MORNING.  HOWEVER IT WAS NOTED THAT CLOUD TOPS WERE LOWERING, AND
THAT TREND IS EXPECTED TO CONTINUE.  SO IT APPEARS WE WILL GRADUALLY
SEE SOME BREAKS IN THE CLOUDS INTO THE AFTERNOON, LEADING TO PARTLY
SUNNY SKIES.  TEMPS 40 TO 45 DEPENDING ON THE AMOUNT OF SUN.

A COLD FRONT WILL APPROACH TONIGHT AND CROSS THE AREA MID DAY
MONDAY.  SOME INSTABILITY SHOWS UP LATE TONIGHT INTO MONDAY MORNING
WITH THE FRONT, SO HAVE INCLUDED THE MENTION OF THUNDER SOUTH OF I-
96.  THE RAINS WILL PICK UP IN COVERAGE LATE TONIGHT AND INTO MONDAY
MORNING, THEN DEPART LATE IN THE DAY AS THE FRONT HEADS EAST.  TOTAL
RAIN SHOULD BE LESS THAN A QUARTER INCH IN MOST PLACES.

HIGH PRESSURE NOSES IN FOR MONDAY NIGHT AND TUESDAY WITH DRY WEATHER
RETURNING.

.LONG TERM...(TUESDAY NIGHT THROUGH SATURDAY)
ISSUED AT 330 AM EDT SUN MAR 19 2017

THE EXTENDED BEGINS COOL AND DRY THROUGH THE MIDDLE OF THE WEEK,
ONLY TO GIVE WAY TO A WET AND ACTIVE PATTERN LATE IN THE PERIOD.

A BROAD 1038MB SURFACE HIGH WILL BE CENTERED OVER CENTRAL MANITOBA
LATE TUESDAY. THIS SYSTEM, ALONG WITH PERSISTENT NORTHWEST FLOW,
WILL BRING FAIR AND CHILLY CONDITIONS TO THE REGION THROUGH THE
MIDDLE OF THE WEEK. PENDING ANY EVOLUTION TO THIS PATTERN, WE SHOULD
SEE SUNNY AND DRY WEATHER STRETCH THROUGH WEDNESDAY AND MOST OF
THURSDAY. WEDNESDAY`S COOLER THAN NORMAL TEMPERATURES (30S) WILL BE
SHORT LIVED, AS HIGH PRESSURE MOVES EAST THURSDAY. RETURN FLOW WILL
AID IN MODERATING TEMPERATURES BACK INTO THE 40S.

LONG RANGE MODELS REMAIN AT ODDS THROUGH THE END OF THE WEEK. BOTH
GFS/ECM DEVELOP RIDGING TO SOME DEGREE AND BRING IN A PERIOD OF WET
WEATHER BEGINNING LATE THURSDAY NIGHT. BEYOND THAT SIMILARITY THERE
ARE TIMING AND PLACEMENT ISSUES. THE HIGH RES EURO HAS COME IN A BIT
FURTHER NORTH THAN THE LAST RUN. THIS IS A WARMER SOLUTION, LIMITING
ANY WINTRY PRECIPITATION. GIVEN THIS TREND, TEMPERATURES COULD PUSH
60 DURING THE DAY FRIDAY. A PRETTY STIFF LOW LEVEL JET (60-70 KTS)
IS FORECAST TO DEVELOP FRIDAY NIGHT. THIS COULD BE SOMETHING TO
WATCH OVER THE COURSE OF THE WEEK, AS IT COULD SIGNAL A GUSTY
PASSAGE OF THE TRAILING COLD FRONT.

THE BIGGEST DIFFERENCE IS HOW THE TWO MODELS HANDLE THE FRONT
THROUGH SATURDAY. THE GFS PUSHES IT AND ITS ASSOCIATED PRECIP WELL
EAST BY 12Z SATURDAY, WHILE THE ECM HAS THE BOUNDARY WASHING OUT
JUST SOUTH OF LOWER MICHIGAN. WET CONDITIONS COULD EXTEND INTO AT
LEAST EARLY SATURDAY WITH COOLER TEMPERATURES MOVING IN NEXT
WEEKEND.

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 110 PM EDT Sun Mar 19 2017

The MVFR cloud deck has been thinning out from east to west across
the forecast area late this morning and early this afternoon. This
trend is expected to continue as we go through the remainder of
the afternoon. KAZO...KBTL and KJXN will likely be the last sites
to see the low clouds scatter out.  Relatively light winds are
forecasted with a weak pressure gradient in place this afternoon.

Tonight rain showers will be moving in from the west late. They
are forecasted to weaken as they move in...and may not make it
to KLAN and KJXN until after 12z. Elevated instability is shown by
some models for Monday morning ahead of the cold front that will
be tracking through. Right now the best potential for a
thunderstorm will be over the southern TAF sites of KAZO...KBTL
and KJXN. There I will have a period of VCTS.

The low level moisture really does not increase until closer to
daybreak on Monday. Thus the TAF forecast will feature ceilings
lowering as we go through the morning...with a risk for IFR for
KMKG by the end of the TAF period.

&&

.MARINE...
ISSUED AT 330 AM EDT SUN MAR 19 2017

WINDS WILL BE STAYING AT 15 KNOTS OR LESS MUCH OF THE SHORT TERM.
WAVES WILL ALSO REMAIN ON THE LOW SIDE.


&&

.HYDROLOGY...
ISSUED AT 1047 AM EDT SAT MAR 18 2017

RIVER LEVELS ARE RUNNING AROUND NORMAL TO A LITTLE BELOW NORMAL.
WITH LESS THAN A HALF INCH OF PRECIPITATION EXPECTED THROUGH THIS
WEEKEND AND THEN NO ADDITIONAL PRECIPITATION UNTIL FRIDAY, NO
FLOODING IS EXPECTED ACROSS THE AREA INTO NEXT WEEKEND. THE
PRECIPITATION NEXT WEEKEND MAY BE ENOUGH TO PUSH RIVER LEVELS UP,
BUT THEY SHOULD REMAIN BELOW BANK FULL.

&&

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

$$

SYNOPSIS...JK
SHORT TERM...JK
LONG TERM...JAM
AVIATION...MJS
HYDROLOGY...63
MARINE...JK



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