Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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000
FXUS63 KGRR 291809
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
209 PM EDT WED OCT 29 2014

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 330 AM EDT WED OCT 29 2014

MOSTLY CLOUDY AND COOL WEATHER CAN BE EXPECTED THE REST OF THE WEEK.
THE COLDEST DAY WILL BE HALLOWEEN WHEN A STRONG CANADIAN COLD FRONT
BLASTS SOUTH THROUGH THE STATE. NORTH WINDS WILL GUST OVER 40 MPH
AND OUR FIRST SNOWFLAKES OF THE SEASON MAY BE SEEN. THE COLD AIR
WILL LINGER INTO SATURDAY THEN TEMPERATURES WILL MODERATE SUNDAY
INTO NEXT WEEK.

&&

.UPDATE...
ISSUED AT 1124 AM EDT WED OCT 29 2014

I INCREASED THE POP TO CONDITIONAL OVER THE WESTERN CWA AS MOST
LOCATIONS WERE AND STILL ARE GETTING MEASURABLE PRECIPITATION. THE
SHOWERS ARE THE RESULT OF MID LEVEL POCKET OF COLD AIR MOVING
THROUGH THE AREA IN CONJUNCTION WITH THE UPPER LEVEL TROUGH AND
ASSOCIATED SHORTWAVE. ALL OF THIS SHOULD BE EAST OF THE AREA BY
LATE THIS AFTERNOON. THAT WILL LOWER INVERSION HEIGHTS AND END THE
PRECIPITATION. WARM ADVECTION AT LOW TO MID LEVELS SETS IN BY
EARLY THIS EVENING WILL HELP END WHATEVER PRECIPITATION REMAINS BY
MID EVENING.

&&

.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 330 AM EDT WED OCT 29 2014

THE COLD BLAST ON HALLOWEEN DAY IS THE MAIN FOCUS. INTENSE PV
ANOMALY IS PROGGED TO DROP SOUTH THROUGH CENTRAL CANADA AND INTO THE
GREAT LAKES REGION ON FRIDAY. THIS FEATURE INDUCES CYCLOGENESIS OVER
THE LOWER GRTLKS REGION ALTHOUGH AT THIS TIME THE MODELS ARE NOT
GOING WITH A PARTICULARLY STRONG SFC LOW. REGARDLESS... THE WINDS
CRANK UP CONSIDERABLY BEHIND THE SFC COLD FRONT WITH TIGHT GRADIENT
BETWEEN THE LOWER GRTLKS RGN SFC LOW AND THE SFC HIGH OVER
MINNESOTA.  GUIDANCE SUGGESTS THE POSSIBILITY OF WIND GUSTS OVER 40
KTS AND WIND ADVISORIES MAY BE REQUIRED. SCATTERED POWER OUTAGES AND
FALLING TREE LIMBS ARE POSSIBLE.

AS FAR AS THE SNOW POTENTIAL ON HALLOWEEN... THE DGZ LOOKS PRETTY
HIGH ABOVE 7K FT. ALSO THE NORTH FLOW BEHIND THE FRONT FRIDAY
AFTERNOON WILL LIKELY LEAD TO ABRUPT DRYING IN SW MI. HAVE KEPT A
MIX OF RAIN/SNOW SHOWERS IN THE FCST BUT AM LEANING TOWARD MOSTLY
RAIN BASED ON SURFACE TEMPS AROUND 40. THE EXCEPTION WOULD BE IN THE
HIGHER ELEVATIONS ALONG/NORTH OF U.S. 10 WHERE SNOW MAY BE MORE
PERSISTENT AND HAVE A CHANCE OF STICKING TO THE GRASS.

DEEP CYCLONIC FLOW AND COLD ADVECTION WITH H8 TEMPS AROUND -3C WILL
LEAD TO EXTENSIVE CLOUDINESS TODAY AS WELL AS SCATTERED LAKE EFFECT
RAIN SHOWERS. TEMPERATURES WILL STRUGGLE TO GET OUT OF THE 40S. IT
WILL BE BREEZY ALTHOUGH NOT AS BAD AS YESTERDAY.

TONIGHT AND THURSDAY THE SURFACE RIDGE MOVES IN BUT LOW LEVEL
MOISTURE LINGERS UNDERNEATH THE SUBSIDENCE INVERSION. THIS SHOULD
RESULT IN A CONTINUATION OF MOSTLY CLOUDY SKIES.

.LONG TERM...(FRIDAY NIGHT THROUGH TUESDAY)
ISSUED AT 330 AM EDT WED OCT 29 2014

A LARGE HIGH PRESSURE SYSTEM WILL BE MOVING OVER THE GREAT LAKES
FRIDAY NIGHT AS THE HALLOWEEN STORM MOVES AWAY FROM LOWER MICHIGAN.
THERE MAY BE SOME LINGERING LAKE EFFECT SNOW SHOWERS DOWN WIND FROM
THE POINTS ON THE WESTERN CWA...AND A FEW SHSN OVER THE EASTERN CWA
DOWNWIND FROM LAKE HURON. 30KT NORTHEAST BOUNDARY LAYER WINDS MAY
BLOW SOME SHSN INLAND. WE INCREASED POPS A BIT OVER THE NE CWA FOR
THAT POSSIBILITY.

WE/LL SEE A COUPLE OF DAYS OF DRY WEATHER AS THE RIDGE SETTLES OVER
MICHIGAN BEFORE THE NEXT COLD FRONT APPROACHES MONDAY. THE SYSTEM
MONDAY INTO TUESDAY WON/T BE NEARLY AS DYNAMIC AS THE SYSTEM THIS
FRIDAY. SCATTERED RAIN SHOWERS SHOULD SUFFICE MONDAY INTO TUESDAY.

SATURDAY WILL BE THE COLDEST DAY WITH HIGHS AROUND 40 AFTER WHICH A
WARMING TREND WILL BOOST TEMPS INTO THE LOWER 50S MONDAY AND TUESDAY.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 208 PM EDT WED OCT 29 2014

CEILINGS AROUND 3000FT ARE IN PLACE ACROSS THE TAF SITES WITH A
VARIANCE BOTH ABOVE INTO THE VFR CATEGORY AND BELOW INTO THE MVFR
CATEGORY. WENT WITH A TEMPO GROUP FOR THE FIRST FOUR HOURS AS THE
CEILINGS WILL LIKELY CONTINUE TO VARY. OVERNIGHT...FELT THAT MVFR
CEILINGS MAY BE MORE PREVALENT TOWARDS LAKE MICHIGAN WITH VFR
INLAND.

CONDITIONS WILL REMAIN CONDUCIVE FOR LAKE GENERATED CLOUDS
ALL THE WAY THROUGH 18Z THURSDAY...THE QUESTION IS WILL THEY BE
ABOVE OR BELOW 3000FT. DECIDED TO GO MORE PESSIMISTICALLY TOWARDS
LAKE MICHIGAN OVERNIGHT GIVEN THE TIME OF YEAR AND TIME OF DAY.
THE HOLES IN THE OVERCAST UPSTREAM THOUGH ARE A BIT CONCERNING.
FEEL SHOWERS WILL GRADUALLY DIMINISH AS WE HEAD THROUGH THE
EVENING HOURS...SO NO REAL RESTRICTION TO VISIBILITIES. A
NORTHWEST WIND OF 8-16 KNOTS THIS AFTERNOON WILL BECOME LIGHT
OVERNIGHT.

&&

.MARINE...
ISSUED AT 330 AM EDT WED OCT 29 2014

WHILE SOMEWHAT UNCONVENTIONAL... WILL ISSUE GALE WARNING ALREADY FOR
FRIDAY AND FRIDAY NIGHT DUE TO VERY HIGH CONFIDENCE.


&&

.HYDROLOGY...
ISSUED AT 330 PM EDT TUE OCT 28 2014

RAINFALL MONDAY NIGHT AND EARLY TUESDAY WAS NOT SIGNIFICANT
ENOUGH TO CAUSE HYDRO ISSUES AND NO HYDRO ISSUES ARE ANTICIPATED
FOR THE REST OF THE WEEK WITH MAINLY DRY WX ANTICIPATED TONIGHT
THROUGH THURSDAY. PCPN THURSDAY NIGHT AND FRIDAY WILL NOT BE
SIGNIFICANT ENOUGH TO CAUSE HYDRO ISSUES SINCE BASIN AVG QPF
AMOUNTS OF ONLY UNDER A HALF OF AN INCH ARE ANTICIPATED THEN.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 5 PM EDT THIS AFTERNOON FOR
     LMZ844>849.

     GALE WARNING FROM 8 AM FRIDAY TO 5 AM EDT SATURDAY FOR
     LMZ844>849.

&&

$$

UPDATE...WDM
SYNOPSIS...MEADE
SHORT TERM...MEADE
LONG TERM...93
AVIATION...DUKE
HYDROLOGY...LAURENS
MARINE...MEADE






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