Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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000
FXUS63 KGRR 270301
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1101 PM EDT SUN OCT 26 2014

LATEST UPDATE...
UPDATE

.SYNOPSIS...
ISSUED AT 310 PM EDT SUN OCT 26 2014

A WARM FRONT WILL MOVE NORTH THROUGH MICHIGAN AND TRIGGER
DEVELOPMENT OF SCATTERED SHOWERS AND STORMS FROM EARLY MONDAY
MORNING THROUGH MONDAY AFTERNOON MAINLY NORTH OF INTERSTATE 96. IT
WILL BE UNSEASONABLY WARM MONDAY. A COLD FRONT WILL BRING SHOWERS
AND THUNDERSTORMS MONDAY NIGHT INTO EARLY TUESDAY. FAIR WEATHER
WILL RETURN FOR MIDWEEK BEFORE A MUCH COOLER AIRMASS MOVES IN LATE
IN THE WEEK.

&&

.UPDATE...
ISSUED AT 1100 PM EDT SUN OCT 26 2014

LOWERED BOTH POPS AND LOW TEMPERATURES FOR TONIGHT BASED ON
CURRENT TRENDS. ALTHOUGH SOME MOISTURE AND WARM AIR ADVECTION WILL
INCREASE...RADAR AND SATELLITE TRENDS SHOW CLOUDS AND SHOWERS
DIMINISHING AS THEY MOVE EAST AND ANY SHOWERS SHOULD HOLD OFF
UNTIL LATE TONIGHT. ALTHOUGH ISOLATED THUNDER CANNOT BE TOTALLY
RULED OUT...CONDITIONS ARE MARGINAL ENOUGH THROUGH THE OVERNIGHT TO
DROP FROM THE FORECAST.

TEMPS ARE ALREADY BELOW FORECAST LOWS IN A FEW PLACES AND WINDS
SHOULD REMAIN LIGHT ENOUGH AND SKIES CLEAR ENOUGH FOR MORE
RADIATIONAL COOLING THROUGH MUC OF THE OVERNIGHT.

&&

.SHORT TERM...(THIS EVENING THROUGH TUESDAY NIGHT)
ISSUED AT 310 PM EDT SUN OCT 26 2014

OUR PRIMARY SHORT TERM FCST CHALLENGE IS TO DETERMINE CONVECTIVE
POTENTIAL FROM VERY LATE TONIGHT THROUGH EARLY TUESDAY.

A FEW SHOWERS AND PERHAPS AN ISOLATED STORM WILL DEVELOP VERY
LATE TONIGHT MAINLY OVER OUR FAR NW FCST AREA AS ELEVATED
INSTABILITY BEGINS TO INCREASE TO THE NORTH OF THE WARM FRONT. A
CONSENSUS OF LATEST SHORT RANGE GUIDANCE SUGGESTS H8 LI/S WILL GO
SLIGHTLY NEGATIVE OVER OUR FAR WNW FCST AREA TOWARD DAYBREAK
MONDAY. HOWEVER A SIGNIFICANT MITIGATING FACTOR GOING AGAINST PCPN
POTENTIAL IS LACK OF MOISTURE OVERNIGHT. THEREFORE ONLY LOW CHC
POPS ARE WARRANTED VERY LATE TONIGHT OVER OUR FAR NW FCST AREA.

A FEW SHOWERS OR STORMS MAY DEVELOP THROUGH THE DAY MONDAY WELL
TO THE NORTH OF I-96 TO THE NORTH OF THE WARM FRONT. HOWEVER DRY
WX IS ANTICIPATED FOR MOST OF THE MORNING AND AFTERNOON HOURS
FOR MOST OF OUR FCST AREA. IT WILL ALSO BE UNSEASONABLY MILD
MONDAY WITH MAX TEMPS POTENTIALLY REACHING THE LOWER 70S NEAR TO
SOUTH OF I-96.

THE APPROACHING COLD FRONT WILL BRING POTENTIAL FOR SHOWERS AND
A FEW STORMS LATE MONDAY NIGHT INTO TUESDAY MORNING WITH DECENT
MOISTURE IN PLACE AHEAD OF THE FRONT WITH PW VALUES UP TO 1.25 TO
1.5 INCHES AND LIFT/FORCING FROM THE FRONT. HOWEVER THE CONVECTIVE
THREAT IS MITIGATED BY SEVERAL FACTORS INCLUDING THE FRONTAL
TIMING AND WEAK INSTABILITY. SEVERE WX IS UNLIKELY IN SPITE OF
STRONG DEEP LAYER SHEAR.

.LONG TERM...(WEDNESDAY THROUGH SUNDAY)
ISSUED AT 310 PM EDT SUN OCT 26 2014

THE MAIN STORY LINES TO THE EXTENDED FORECAST CONTINUE TO DEAL WITH
THE PUSH OF COLD AIR THAT COMES IN BEHIND THE EARLY WEEK SYSTEM AND
THEN THE POSSIBILITY OF THE SEASONS FIRST REAL FLAKES...ON HALLOWEEN
NONETHELESS.

THE BROAD UPPER LOW ROTATES WELL TO THE NORTHEAST BY WEDNESDAY. ON
THE BACK SIDE WINDS TURN WESTERLY AS COOLER AIR CONTINUES TO FILTER
INTO THE REGION. SOME SCATTERED LAKE EFFECT SHOWERS MAY DEVELOP AS
WE GO THROUGH THE DAY WEDNESDAY. CHANCES WILL TAPER OFF AS WE GO
THROUGH WEDNESDAY AFTERNOON.

AS WE DRAW NEAR THE END OF THE WEEK WE WILL BE WATCHING A SOMEWHAT
TRICKY SETUP. THIS ACTUALLY INVOLVES THE SYSTEM THAT IS HURRICANE
ANA OUT IN THE PACIFIC. IT WILL EVENTUALLY MERGE WITH ANOTHER
PACIFIC STORM AND COME ASHORE OVER BRITISH COLUMBIA IN THE EARLY
PART OF THIS WEEK. MODEL GUIDANCE TYPICALLY DOES NOT HANDLE THIS
KIND OF THING VERY WELL. CURRENT THINKING IS THAT A WEAKENING
SHORTWAVE WILL EJECT SOUTHEASTWARD OUT OF THE CENTRAL PLAINS REGION
AND JUST SOUTH OF LOWER MICHIGAN. AT THE SAME TIME A BROAD UPPER LOW
AND ASSOCIATED JET MAX WILL DIG SOUTHWARD. WE WILL SEE AN INITIAL
WEST TO EAST CREEP OF MOISTURE WHILE A REDEVELOPING LOW TAKES SHAPE
OVER THE EASTERN GREAT LAKES. THOUGH NOT A LOT OF MOISTURE IS IN
PLAY HERE WE WILL STILL SEE SOME SHOWERS ON FRIDAY. IF COLDER AIR
ARRIVES QUICK ENOUGH FRIDAY AFTERNOON INTO FRIDAY EVENING...SNOW MAY
EVENTUALLY MIX IN FOR THE HALLOWEEN FORECAST.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 750 PM EDT SUN OCT 26 2014

VFR CONDITIONS WILL CONTINUE THROUGH MONDAY AFTERNOON. SOUTHEAST
WINDS WILL PICK UP DURING THE MORNING WITH SOME GUSTS OVER 20
KNOTS AFTER 15Z. THERE COULD BE ISOLATED SHOWERS LATE TONIGHT OR
EARLY MONDAY MORNING BUT THESE SHOULD NOT AFFECT VISIBILITY AND
CEILINGS WILL BE ABOVE 6000 FEET AGL.


&&

.MARINE...
ISSUED AT 310 PM EDT SUN OCT 26 2014

WAVE HEIGHTS WILL CONTINUE TO SUBSIDE THROUGH THIS EVENING WITH
A RIDGE OF HIGH PRESSURE IN PLACE. HOWEVER WIND SPEEDS AND WAVE
HEIGHTS WILL GRADUALLY INCREASE ON MONDAY BUT WILL STAY BELOW
SMALL CRAFT CRITERIA. HOWEVER A SMALL CRAFT ADVISORY WILL LIKELY
BE NEEDED AGAIN FOR TUESDAY DUE TO WAVE HEIGHTS OF AT LEAST 4 TO 5
FEET IN COLD AIR ADVECTION BEHIND THE COLD FRONT.


&&

.HYDROLOGY...
ISSUED AT 1136 AM EDT SUN OCT 26 2014

A FEW CHANCES FOR RAIN EXIST OVER THE NEXT SEVERAL DAYS. THE KEY
NOTE HERE IS THAT THERE IS NOT MUCH IN THE WAY OF SUPPORT FOR ANY
LARGE IMPACT EVENTS. EACH EPISODE BRINGS THE POTENTIAL FOR AROUND
ONE-QUARTER OF AN INCH OR SO OF MOISTURE. THIS WOULD LIKELY BE HIGHER
IN ANY CONVECTIVE SITUATIONS. THOSE CHANCES EXIST MAINLY LATE TONIGHT
INTO MONDAY MORNING AND AGAIN EARLY TUESDAY. HOWEVER...POTENTIAL
FOR CONVECTION IS RATHER LIMITED. GENERAL RAINFALL AMOUNTS THROUGH
THE NEXT 7 DAYS LOOK TO BE ON THE ORDER OF ONE-HALF AN INCH TO ONE
INCH. IN ADDITION...MANY AREAS HAVE ONLY RECEIVED AROUND ONE-TENTH
OF AN INCH OR LESS SINCE THE 15TH OF OCTOBER. AREA RIVERS WILL
LIKELY NOT BE OF ANY CONCERN.

&&

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

$$

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






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