Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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000
FXUS63 KGRR 191514
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1114 AM EDT SUN APR 19 2015

LATEST UPDATE...
HYDRO

.SYNOPSIS...
ISSUED AT 330 AM EDT SUN APR 19 2015

A LARGE AREA OF LOW PRESSURE WILL MOVE OVER LOWER MICHIGAN LATER
TODAY AND TONIGHT...BRINGING RAIN TO MUCH OF THE LOWER PENINSULA.
SHOWERY WEATHER WILL BE WITH US THROUGH THURSDAY. MUCH COLDER AIR
WILL FLOW IN BEHIND THE LOW AND WE/LL SEE SOME WET SNOW MIX IN
WITH THE RAIN AT TIMES TUESDAY NIGHT THROUGH THURSDAY. MINOR SNOW
ACCUMULATIONS ARE POSSIBLE TUESDAY NIGHT ALONG US-10 INLAND FROM
THE LAKE. AFTER HIGHS TODAY IN THE 60S...TEMPERATURES WILL BECOME
MUCH COOLER WITH HIGHS IN THE MID 40S TO LOWER 50S THROUGH THE END
OF THE WEEK.

&&

.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 330 AM EDT SUN APR 19 2015

FORECAST CONCERNS REMAIN RELATED TO THE EVOLUTION OF THE LARGE AREA
OF LOW PRESSURE HEADED TOWARD THE GREAT LAKES. SHORT RANGE MODELS
ARE IN GOOD AGREEMENT AND HAVE BEEN CONSISTENT IN SHOWING RAIN
DEVELOPING AROUND NOON OVER THE SRN CWA AND THEN MOVING NORTH. THIS
SYSTEM IS A PHASE BETWEEN A LOW OVER SW ONTARIO AND A LOW MOVING
NORTH FROM THE GULF. THE GULF INFLOW WILL PROVIDE PLENTY OF MOISTURE
TO WORK WITH COURTESY OF A 60 KT LLJ. INSTABILITY IS LACKING THOUGH
SO THUNDER ISN/T MUCH OF A CONCERN. STRONG ISENTROPIC LIFT WILL
EVENTUALLY OVERCOME THE DRY LEVELS OF THE LOWER ATMOSPHERE SEEN IN
00Z SOUNDINGS BY LATE MORNING. SHOWERS WILL MOVE NORTH ACROSS THE
CWA THIS AFTERNOON AND CONTINUE TONIGHT. THIS SYSTEM TAKES ON A
LITTLE BIT OF A NEGATIVE TILT WHICH USUALLY SIGNIFIES THAT IT/S A
WET SYSTEM. IN FACT QPF OF 3/4 TO AROUND AN INCH SEEMS LIKELY
THROUGH TUESDAY AS THE SFC LOW AND THEN THE UPPER SYSTEM MOVES
THROUGH. TEMPS WILL COOL FROM FROM MONDAY INTO TUESDAY. IT/S NOT OUT
OF THE QUESTION THAT SOME WET SNOW COULD MIX IN WITH THE SHOWERS
TUESDAY NIGHT ALONG US-10...OTHERWISE JUST RAIN SHOWERS ARE EXPECTED
THROUGH TUESDAY.

.LONG TERM...(TUESDAY NIGHT THROUGH SATURDAY)
ISSUED AT 330 AM EDT SUN APR 19 2015

THE MAIN STORY CONTINUES TO BE THE UNSEASONABLY COLD WEATHER
ASSOCIATED WITH A LARGE UPPER LOW WHICH IMPACTS THE REGION MOST OF
THE COMING WEEK. HIGHS WILL ONLY BE IN THE 40S WEDNESDAY AND
THURSDAY...FOLLOWED BY SLOW MODERATION HEADING INTO NEXT WEEKEND.

THE COLD AIR ALOFT AND CYCLONIC FLOW WILL RESULT IN A GREAT DEAL OF
DIURNAL CLOUDINESS BUT WHERE SKIES MANAGE TO CLEAR AT NIGHT WE COULD
EASILY SEE SOME READINGS DOWN INTO THE 20S. WHILE SCATTERED RAIN OR
MIXED RAIN AND SNOW SHOWERS ARE EXPECTED THROUGH AT LEAST
THURSDAY... THE GFS AND ECMWF CONTINUE TO SHOW LIMITED QPF.

HOWEVER NORMALLY IN THIS SYNOPTIC SET UP WE SEE A FEW DECENT
SHORTWAVES ROTATING AROUND THE UPPER LOW WHICH LEAD TO RELATIVELY
BRIEF PERIODS OF HEAVIER/CONVECTIVE SHOWERS PASSING THROUGH. SO WE
STILL CANT RULE OUT THE POSSIBILITY OF SOME LIGHT SNOW ACCUMULATIONS
TUESDAY NIGHT AND/OR WEDNESDAY NIGHT NORTH OF I-96... AND
PARTICULARLY IN THE HIGHER ELEVATIONS NORTH OF U.S. 10.

THE RISK OF SHOWERS DECREASES TOWARD THE END OF THE WEEK AS THE
UPPER LOW NUDGES EAST AND SURFACE RIDGING NOSES IN.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 745 AM EDT SUN APR 19 2015

MUCH OF THE DAY WILL REMAIN VFR ALTHOUGH CIGS WILL BE LOWERING
RAPIDLY FROM SOUTH TO NORTH AFTER ABOUT 20Z AS RAIN SPREADS IN.
EXPECT PRIMARILY MVFR CONDITIONS BY 00Z AND MOSTLY IFR CONDITIONS
BY 03Z TONIGHT WITH PERSISTENT MODERATE RAIN.

WINDS WILL REMAIN STRONG/GUSTY OUT OF THE EAST TODAY AND THIS
EVENING ALTHOUGH LOOK FOR WINDS TO BECOME SOUTHERLY AFTER 06Z
SOUTH AND EAST OF GRR AS THE SFC LOW TRACKS ACROSS WRN LWR MI.


&&

.MARINE...
ISSUED AT 330 AM EDT SUN APR 19 2015

NO CHANGES TO THE SMALL CRAFT ADVISORY. WINDS WILL REMAIN GUSTY FROM
THE EAST TODAY AS LOW PRESSURE


&&

.HYDROLOGY...
ISSUED AT 1114 AM EDT SUN APR 19 2015

PERIODS OF RAIN ARE EXPECTED TO DEVELOP LATE THIS AFTERNOON AND
AFFECT THE AREA OVER THE NEXT COUPLE OF DAYS. THE LIGHTER VARIETY OF
PRECIPITION MAY EXTENT INTO MIDWEEK. THOUGH WE WILL SEE A DECENT SOIL
SOAKING IT SHOULD NOT BE SUBSTANTIAL ENOUGH TO CREATE FLOODING
CONCERNS. GRADUAL BUT MINOR RISES ARE LIKELY...SUSPECTING THAT
THIS WOULD STAY WITHIN BANKS FOR MOST LOCATIONS. I WOULD NOT RULE
OUT A COUPLE OF SITES FLIRTING WITH ADVISORY STAGE AS WE GO INTO
TUESDAY...ESPECIALLY IF ANY MODERATE RAINFALL IS MORE PERSISTENT
WITH THE FIRST COUPLE OF ROUNDS OF MOISTURE. OTHERWISE...AREA
RIVERS ARE WELL BEHAVED THROUGH THE PERIOD.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR LMZ844>848.

&&

$$

SYNOPSIS...04
SHORT TERM...04
LONG TERM...MEADE
AVIATION...MEADE
HYDROLOGY...JAM
MARINE...04







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