Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 201652
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1255 PM EDT SUN APR 20 2014

LATEST UPDATE...
AVIATION

.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 18Z TAFS THROUGH 18Z MONDAY)
ISSUED AT 1255 PM EDT SUN APR 20 2014

VFR CONDITIONS WILL CONTINUE THIS AFTERNOON AND TONIGHT WITH JUST
SOME HIGH CLOUDS AROUND AND SOUTH WINDS OF AROUND 10 KTS WITH A FEW
HIGHER GUSTS. A FEW LIGHT RAIN SHOWERS WILL DEVELOP IN KMKG MONDAY
MORNING AND A LITTLE FURTHER SE INTO KGRR AROUND MIDDAY MONDAY. THE
SHOWERS WILL HOLD OFF AT THE REST OF THE TERMINALS UNTIL AFTER 18Z
MONDAY. CONDITIONS THROUGH 18Z MONDAY SHOULD REMAIN VFR.

&&

.FIRE WEATHER...
ISSUED AT 1127 AM EDT SUN APR 20 2014

HIGH FIRE DANGER DEVELOPING THIS AFTERNOON AS TEMPS RISE INTO THE
LOWER 70S WITH DEW PTS OF 25-35. MIN RH VALUES ARE EXPECTED TO
FALL TO 20 TO 25 PCT MID TO LATE AFTERNOON DURING PK HEATING...
PARTICULARLY SOUTH OF A LINE FROM MUSKEGON TO MT PLEASANT WHERE
ONLY HIGH THIN CLOUDINESS ARE PRESENT.

WIND SPEEDS SHOULD BE GENERALLY 10-15 MPH ALTHOUGH SOME GUSTS
AROUND 20 MPH POSSIBLE AS DEEPER MIXING DEVELOPS. CONDITIONS COULD
APPROACH RED FLAG WARNING CRITERIA ALTHOUGH WIND SPEEDS AND TEMPS
ARE THE LIMITING FACTORS.

HOWEVER SINCE WE ARE IN PRE GREEN UP MODE AND THE FINE FUELS ON
THE GROUND ARE EXTREMELY DRY... FIRES COULD SPREAD EASILY.
YESTERDAYS HIGH TEMPS WERE ONLY IN THE LOW 60S AND THERE WERE SOME
REPORTS OF GRASS FIRES WHICH SPREAD QUICKLY.

COORDINATED THE HIGH FIRE DANGER WITH THE DNR AND FOREST SERVICE
THIS MORNING. ISSUED A PUBLIC INFORMATION STATEMENT ON THE HIGH
FIRE DANGER WITH CALLS TO ACTIONS. SOCIAL MEDIA AND NWS GRR
HOMEPAGE ALSO USED TO GET THE WORD OUT.

&&

.HYDROLOGY...
ISSUED AT 1153 AM EDT SUN APR 20 2014

MINOR FLOODING EXISTS ON THE MUSKEGON RIVER AT CROTON AND EVART.
THE DOWNWARD TREND CONTINUES ON ALL AREA RIVERS AND TRIBUTARIES.
WE SHOULD SEE A FEW MORE ADVISORIES DROP OFF THE LIST OVER THE
NEXT 24 HOURS OR SO. HOWEVER...LOCAL IMPACTS MAY STILL BE EVIDENT
OVER THE NEXT SEVERAL DAYS ALONG THE MUSKEGON RIVER.

LIGHT RAIN IS POSSIBLE TONIGHT AHEAD OF A SLOW MOVING COLD FRONT.
BEST CHANCES TONIGHT SHOULD REMAIN ALONG AND NORTH OF HIGHWAY 10.
THE FRONT WILL FINALLY PUSH THROUGH MONDAY AFTERNOON AND THATS
WHEN RAIN IS MORE LIKELY THROUGHOUT THE AREA. PRECIPITATION
AMOUNTS WILL BE RATHER LIGHT AND SHOULD NOT HAVE ANY ADVERSE
AFFECTS ON RIVERS. ANOTHER SHOT OF RAIN WILL MOVE IN LATER IN THE
WORK WEEK BUT IT LOOKS LIKE THE HEAVIEST SHOULD REMAIN WEST OF
LOWER MICHIGAN.

&&

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

$$

SYNOPSIS...93
SHORT TERM...93
LONG TERM...MJS
AVIATION...LAURENS
FIRE WEATHER...MEADE
HYDROLOGY...JAM







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