Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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000
FXUS63 KGRR 230213
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
913 PM EST SAT NOV 22 2014

LATEST UPDATE...
UPDATE/MARINE

.SYNOPSIS...
ISSUED AT 328 PM EST SAT NOV 22 2014

LIGHT RAIN AND DRIZZLE THROUGH SUNDAY WILL GIVE WAY TO STEADY RAIN
SUNDAY NIGHT AND MONDAY MORNING. THIS WILL LEAD TO CONTINUED
MELTING SNOW AND WILL HELP RIVERS TO RISE. GUSTY WINDS DEVELOP MONDAY
AFTERNOON AND EVENING AS RAIN GRADUALLY CHANGES TO SNOW. THE
TUESDAY MORNING COMMUTE LOOKS TO BE THE MOST IMPACTED FROM ANY
STANDING WATER LEFT OVER WHICH WILL FREEZE UP AND ALSO DUE TO THE
SNOW SHOWERS ESPECIALLY ALONG/WEST OF U.S. 131. THERE IS A THREAT
FOR SOME LIGHT SNOW WEDNESDAY NIGHT AND THANKSGIVING DAY.

&&

.UPDATE...
ISSUED AT 912 PM EST SAT NOV 22 2014

WE HAVE FRESHENED UP THE FCST THIS EVENING TO ACCOUNT FOR THE
LATEST TRENDS IN TEMPS AND RAIN CHCS.

TEMPS HAVE BEEN CONTINUING TO GENERALLY CLIMB THIS EVENING WITH
THE SSW FLOW BRINGING IN THE WARMER AND MORE MOIST AIR. IN
FACT...TEMPS HAVE REACHED 50 DEGREES ACROSS THE FAR SRN AND SWRN
PORTION OF THE CWFA. TEMPS COULD DROP A DEGREE OR TWO COMPARED TO
CURRENT READINGS...HOWEVER WE GENERALLY EXPECT STEADY OR SLOWLY
RISING TEMPS THROUGH THE NIGHT TONIGHT.

WE HAVE DROPPED PCPN CHCS DOWN INTO THE CHC CATEGORY FOR THE
ENTIRE CWFA. AREAS OF DRIZZLE AND FOG WILL REMAIN POSSIBLE THROUGH
THE NIGHT TONIGHT. A BATCH OF SHOWERS THAT AFFECTED THE SRN
PORTION OF THE CWFA EARLIER HAVE MOVED EAST OF THE AREA. THOSE
SHOWERS WERE AT THE LEADING EDGE OF LOW LEVEL MOISTURE
TRANSPORT...AND THAT HAS SHIFTED EAST OF THE AREA ALSO. THERE ARE
A FEW LIGHT SHOWERS DOWN ACROSS CENTRAL INDIANA THAT COULD CLIP
THE SE PORTION OF THE AREA...HOWEVER THEY ARE NOT SIGNIFICANT. THE
NEXT GOOD CHC OF RAIN WILL COME SUN AFTERNOON AND SUN NIGHT AS THE
MAIN WAVE MOVES TOWARD THE AREA.

&&

.SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT)
ISSUED AT 328 PM EST SAT NOV 22 2014

PRIMARY IMPACT WEATHER CENTERS ON FAIRLY SIGNIFICANT RAIN SUNDAY
NIGHT/MONDAY MORNING (SEE HYDRO SECTION FOR MORE DETAILS) ALONG WITH
INCREASING WINDS ON MONDAY AS RAIN CHANGES TO SNOW AND BLOWING SNOW
MONDAY NIGHT. TEMPERATURES WILL DROP TO JUST ABOVE FREEZING BY THE
MONDAY EVENING COMMUTE...SO IT IS NOT CERTAIN IF THERE WILL BE ANY
IMPACTS TO TRAVEL BY THEN. TEMPS DROP INTO THE UPPER 20S BY EARLY
TUESDAY MORNING SO SLICK CONDITIONS ARE QUITE LIKELY FOR THE TUESDAY
MORNING COMMUTE WITH ANY STANDING WATER FREEZING IN PLACE. WITH THE
AMOUNT OF RAIN COMING THIS WAY...THERE MAY BE QUITE A BIT OF
STANDING WATER ON THE ROADS HEADING INTO MONDAY NIGHT...SO TRAVEL
IMPACTS ARE PROBABLE.

THERE IS SOME VARIABILITY IN 12Z MODEL GUIDANCE REGARDING PLACEMENT
AND STRENGTH OF THE APPROACHING LOW AS IT DEEPENS IN THE GREAT LAKES
REGION. THE GFS MAY BE OVERDOING SFC CYCLOGENESIS AS IT IS 7-12
MB DEEPER THAN THE ECMWF AND GEM AT 06Z MONDAY. SFC LOW TRACK SHOULD
BE SOMEWHERE OVER LAKE MICHIGAN OR SW LOWER MI BY 06Z MONDAY AND BY
18Z IT WILL LIKELY BE OVER THE STRAITS AREA OR NORTHERN LAKE HURON.

WITH A 1020 MB HIGH DEVELOPING OVER THE SOUTH CENTRAL PLAINS THERE
WILL BE A FAIRLY DECENT PRESSURE GRADIENT IN PLACE OVER SW MI.
MONDAY EVENING LOOKS GUSTY...WITH 25-35 MPH GUSTS EXPECTED (COULD BE
40+ MPH ALONG THE IMMEDIATE COAST). GIVEN ABUNDANT MOISTURE ON THE
BACK SIDE OF THIS SYSTEM...LAKE ENHANCED RAIN COMES INTO PLAY UP
UNTIL APPROXIMATELY 18Z MONDAY WITH WSW FLOW AND PERHAPS AN AID FROM
LAKE SUPERIOR GIVEN H850 GEOPOTENTIAL HEIGHTS AND SFC WIND FIELD
COMING RIGHT OFF SUPERIOR AND NORTHERN WISCONSIN.

LAKE ENHANCED RAIN/SNOW MIX IS EXPECTED FROM 18Z MON-00Z TUE BEFORE
TURNING TO ALL SNOW. WHILE THE DGZ APPEARS FAIRLY DEEP (AROUND A
5K-7K FT LAYER) MOST OF THE LIFT WILL BE OFFSET BELOW THE DGZ...AND
1000-850 MB OMEGAS WILL BE MODEST (IN THE 4-6 MICROBARS/SEC RANGE
ALONG THE LAKESHORE). NEVERTHELESS...WITH A SATURATED ENVIRONMENT
LIKELY TO THE 15K OR 20K FT LEVEL...PLENTY OF SNOW CRYSTALS WILL BE
GENERATED IN THE COLUMN COINCIDENT WITH SFC TEMPS DROPPING TO AROUND
FREEZING BY 00Z TUE. ACCUMULATIONS ARE LIKELY FROM 00Z-12Z TUE WITH
A GENERAL 1"-4" OF SNOW EXPECTED...HEAVIEST IN MASON/LAKE/OCEANA
COUNTIES GIVEN A WSW FLOW TURNING WESTERLY. SOME LOCATIONS MAY
RECEIVE OVER 4" IN THESE COUNTIES BY 12Z TUE. LOCATIONS SUCH AS
LANSING...JACKSON...AND BATTLE CREEK WILL SEE LITTLE IF ANY
ACCUMULATION. SLOWED TRAVEL LOOKS LIKELY FOR THE TUESDAY MORNING
COMMUTE GIVEN THE FALLING/ACCUMULATING SNOW AND ICY ROADS.

.LONG TERM...(TUESDAY THROUGH SATURDAY)
ISSUED AT 328 PM EST SAT NOV 22 2014

THE MID RANGE MODELS DO NOT GIVE A LOT OF CONFIDENCE IN THE LONG
TERM. WHAT MODEL CONSENSUS THERE IS CALLS FOR MORE COLD CANADIAN AIR
AND LAKE EFFECT SNOW SHOWERS. HOWEVER... THE SHORT WAVES FORECAST TO
ENHANCE THE LAKE OUTPUT ARE ALL OVER THE PLACE... DEPENDENT ON MODEL
AND FORECAST CYCLE.

THE LONG TERM WILL BEGIN WITH LAKE EFFECT SNOW ONGOING THROUGH
TUESDAY NIGHT. A NORTHERN STREAM SYSTEM IS THEN FORECAST TO IMPACT
THE AREA INTO THANKSGIVING DAY. HOWEVER... A SOUTHERN STREAM SYSTEM
EXPECTED TO MOVE UP THE ATLANTIC COAST THROUGH THIS PERIOD MAY PULL
ENERGY TO ITSELF AND WEAKEN THE NORTHERN STREAM STORM OVER THE GREAT
LAKES. STILL EXPECTING SNOW THROUGH MOST OF THE LONG TERM... BUT
INTENSITY IS A QUESTION MARK AND MAY BE DOWN. LIGHT LAKE EFFECT SNOW
IS POSSIBLE THURSDAY NIGHT INTO THE WEEKEND.

TEMPERATURES THROUGH THE LONG TERM WILL BE BELOW NORMAL. NORMAL
HIGHS ARE AROUND 40 DEGREES AND NORMAL LOWS ARE IN THE UPPER 20S.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 641 PM EST SAT NOV 22 2014

CONDITIONS WILL VARY THIS EVENING FROM IFR/LIFR ACROSS SOUTH
CENTRAL LOWER MICHIGAN TO MVFR ACROSS WESTERN LOWER MICHIGAN. THE
RECENT IMPROVEMENT IN CONDITIONS FROM MKG TO AZO SHOULD HOLD UNTIL
LATE EVENING WHEN LOW CLOUDS AND FOG ARE EXPECTED TO BRING IFR
WHICH WILL PERSIST OVERNIGHT. WINDS WILL CONTINUE FROM THE SOUTH
SOUTHWEST AT AROUND 10 KNOTS.


&&

.MARINE...
ISSUED AT 912 PM EST SAT NOV 22 2014

WE HAVE EXTENDED THE SMALL CRAFT ADVISORY OUT INTO MON MORNING...
AND THEN ISSUED A GALE WATCH BEGINNING MON MORNING AND GOING INTO
TUE. WINDS ARE FCST TO REMAIN UP IN THE SCA CATEGORY THROUGH SUN
NIGHT BEFORE INCREASING SIGNIFICANTLY ON MON AFTERNOON BEHIND THE
FRONT. THE WINDS WILL BECOME OFFSHORE LATER ON SUN AHEAD OF THE
INCOMING SYSTEM...SO WAVES WILL NOT BE VERY BIG. AS THE COLDER AIR
COMES IN LATER ON MON AND TIGHT GRADIENT MOVES IN WITH THE FLOW
BECOMING ONSHORE...GALES WILL BECOME MORE LIKELY AT THAT TIME.

&&

.HYDROLOGY...
ISSUED AT 328 PM EST SAT NOV 22 2014

GENERAL THINKING HAS NOT CHANGED VERY MUCH. STORM TOTAL RAINFALL
BY MONDAY AFTERNOON SHOULD BE ON THE ORDER OF 1.00"-1.50" ACROSS
THE ENTIRE CWA. FACTORING IN A MELT-OFF OF 0.50"-1.00" LIQUID FROM
THE SNOWPACK...AND SUBSTANTIAL RIVER RISES ARE HIGHLY LIKELY. THE
12Z GFS IS PROBABLY OVERDONE WITH >2.00" OF TOTAL RAINFALL FROM
SOUTH HAVEN TO GRAND RAPIDS BY MONDAY AFTERNOON. USING THIS AS THE
WORST CASE SCENARIO...MANY RIVERS WOULD REACH OR EXCEED BANKFULL
AND A FEW FORECAST POINTS COULD COME CLOSE TO MINOR FLOOD STAGE.
AGAIN...THIS IS NOT BEING FORECASTED BUT NEVERTHELESS SHOULD GIVE
SOME REFERENCE SHOULD THE WORST-CASE SCENARIO UNFOLD WITH 2" OF
RAIN AND A COMPLETE SNOW MELT ESPECIALLY ACROSS THE WESTERN GRAND
RIVER/MUSKEGON RIVER BASINS. NO FLOODING IS CURRENTLY
FORECASTED. THE COLDER WEATHER MOVING IN FOR TUESDAY AND BEYOND
MAY HELP SLOW OR EVEN REDUCE THE AMOUNT OF RIVER RISE THAT WOULD
NORMALLY OCCUR WITH THAT MUCH LIQUID FLOWING INTO THE RIVER BASINS.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...GALE WATCH FROM MONDAY MORNING THROUGH TUESDAY MORNING FOR
     LMZ844>849.

     SMALL CRAFT ADVISORY UNTIL 10 AM EST MONDAY FOR LMZ844>849.

&&

$$

UPDATE...NJJ
SYNOPSIS...HOVING
SHORT TERM...HOVING
LONG TERM...63
AVIATION...OSTUNO
HYDROLOGY...HOVING
MARINE...NJJ





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