Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 200716
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
316 AM EDT SUN APR 20 2014

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

.SYNOPSIS...
ISSUED AT 316 AM EDT SUN APR 20 2014

A SLOW MOVING COLD FRONT WILL BE A FOCUS FOR SHOWERS TONIGHT THROUGH
MONDAY. WARMER AIR WILL SURGE NORTHWARD INTO LOWER MICHIGAN TODAY
AND MONDAY YIELDING HIGHS IN THE 70S BEFORE COOLER AIR FOLLOWS
TUESDAY AND WEDNESDAY.

&&

.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 316 AM EDT SUN APR 20 2014

FORECAST CONCERNS DEAL WITH THE APPROACHING COLD FRONT AND CHANCES
FOR RAIN TONIGHT AND MONDAY. OVERALL THE FORECAST IS ON TRACK AND
ONLY MINOR TWEAKS WERE MADE.

REGIONAL RADAR SHOWS A BAND OF SHOWERS STRETCHING FROM SOUTHERN
MINNESOTA NORTHEASTWARD TO NORTHERN LAKE HURON. THESE SHOWERS
COINCIDE WITH THE LOCATION OF A SLOW MOVING COLD FRONT. MODEL TRENDS
OVER THE PAST 24 HRS HAS BEEN TO SLOW DOWN THE MOVEMENT OF THE
FRONTAL BOUNDARY. THAT WON/T AFFECT TODAY/S FORECAST MUCH. STILL
EXPECTED HIGHS IN THE LOWER 70S WITH SOME SUNSHINE OVER THE SOUTHERN
2/3 OF THE CWA. QUITE A BIT OF CLOUDINESS EXPECTED OVER THE NRN CWA
CLOSER TO THE FRONTAL BOUNDARY. CHC POPS REMAIN ACROSS THE FAR NRN
CWA THIS AFTERNOON.

THE REST OF THE FORECAST IS JUST TIMING THE SHOWERS THROUGH THE CWA.
LIKELY POPS EXPECTED OVER THE NRN CWA TONIGHT MOVING SOUTH THROUGH
THE CWA MONDAY. THE SLOWER TIMING OF THE COLD FRONT WILL ALLOW FOR A
BIT MORE INSTABILITY TO DEVELOP. THE SHORT RANGE MODELS WERE A BIT
MORE AMBITIOUS WITH INSTABILITY IN THE FORM OF LOWER ELEVATED LI/S
MONDAY OVER THE NW CWA. WE ADDED SOME THUNDER TO THE NW CWA MONDAY
AFTERNOON. IT/S IN THIS AREA THAT MUCAPE CLIMBS TO 600 J/KG AFTER
18Z JUST AHEAD OF THE SFC LOW CROSSING CENTRAL LOWER.

COOLER AIR WILL FLOW INTO LOWER MICHIGAN MONDAY NIGHT AND TUESDAY
BEHIND THE LOW. THIS WASN/T A DEEP LOW TO BEGIN WITH SO WINDY
CONDITIONS ARE NOT EXPECTED TUESDAY. HIGHS WILL FALL BACK INTO THE
50S TUESDAY.

.LONG TERM...(TUESDAY NIGHT THROUGH SATURDAY)
ISSUED AT 316 AM EDT SUN APR 20 2014

THE MAIN CHALLENGE IN THE LONG TERM DEALS WITH THE TIMING OF THE
COLD FRONT.

MODELS IN FAIRLY GOOD AGREEMENT ON TRACKING A COLD FRONT THROUGH THE
REGION THU NIGHT...ALTHOUGH THE HIGH RES EURO LOOKS WEAKER WITH THIS
FEATURE.  WILL MAINTAIN THE HIGHEST POPS FOR THE LONG TERM PERIOD
THEN.  THIS SYSTEM WILL PICK UP SOME GULF MOISTURE AND CONTAIN LIFT
WHICH SUPPORTS THE PRECIPITATION.  MOST LOCATIONS SHOULD SEE A RAIN
SHOWER...SO LIKELY POPS WILL BE FORECASTED.  GFS SHOWS WEAK
INSTABILITY...BUT HIGH RES EURO KEEPS THE INSTABILITY SOUTH.  THIS
IS SOMETHING TO MONITOR...NOT CONFIDENT ENOUGH ON THE THUNDER THREAT
TO ADD IT TO THE FORECAST AT THIS TIME.

THE UPPER LOW PIVOTS THROUGH THE GREAT LAKES REGION FRIDAY INTO
FRIDAY NIGHT.  SO WILL MAINTAIN A LOW RISK FOR SHOWERS THEN.

WITH HIGH PRESSURE IN CONTROL FOR TUE NIGHT THROUGH WED...THE
FORECAST WILL BE KEPT DRY.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1134 PM EDT SAT APR 19 2014

VFR CONDITIONS SHOULD PREVAIL THROUGH MOST OF SUNDAY NIGHT. WINDS
WILL FROM THE SOUTH SOUTHEAST FROM 20 TO 30 KNOTS FROM 500 FT TO
1500 FT AGL OVERNIGHT BUT GIVEN THE 5 TO 10 KNOT SURFACE WINDS
SEEMS THE SHEAR IS NOT ENOUGH FOR SIGNIFICANT LLWS. WINDS INCREASE
TO 10 TO 20 KNOTS WITH HIGHER GUSTS DURING SUNDAY AFTERNOON BUT
SKIES STAY CLEAR BELOW 12000 FT AGL.


&&

.HYDROLOGY...
ISSUED AT 330 PM EDT SAT APR 19 2014

MINOR TO MODERATE FLOODING CONTINUES ON THE MUSKEGON RIVER...
OTHERWISE MUCH QUIETER CONDITIONS ARE SEEN ON AREA RIVERS AND
TRIBUTARIES. LOCAL FLOODING IMPACTS WILL CONTINUE ALONG THE MUSKEGON
RIVER FROM OSCEOLA COUNTY SOUTHWEST THROUGH MECOSTA...NEWAYGO...AND
MUSKEGON COUNTIES. WITH A RECEDING TREND...THE IMPACTS WILL BE LESS
AND LESS THROUGH THE WEEKEND AND INTO EARLY NEXT WEEK.

ALL AREAL FLOOD WARNINGS HAVE BEEN CANCELLED. QPF AMOUNTS SUNDAY
NIGHT THROUGH TUESDAY MORNING ARE RELATIVELY LIGHT AND SHOULD NOT
CHANGE THE FALLING RIVER LEVELS MUCH.

&&

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

$$

SYNOPSIS...93
SHORT TERM...93
LONG TERM...MJS
AVIATION...WDM
HYDROLOGY...HOVING









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