Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 091744
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1244 PM EST TUE FEB 9 2016

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 256 AM EST TUE FEB 9 2016

SIGNIFICANT WEATHER CHANGES ARE IN STORE FOR SOUTHWEST MICHIGAN
STARTING THIS AFTERNOON.  COLDER AIR WILL POUR IN OVER THE LAKE
GIVING THE LAKESHORE AREAS A PROLONG PERIOD OF LAKE EFFECT SNOWS.
SEVERAL AREAS WILL SEE OVER SIX INCHES OF SNOW FROM THIS AFTERNOON
THROUGH THURSDAY MORNING. FURTHER INLAND IT WILL ALSO BECOME
COLD...BUT THE SNOWFALL WILL BE LIGHTER...GENERALLY 2 TO 4 INCHES
THROUGH THURSDAY. HIGH TEMPERATURES BOTH WEDNESDAY AND THURSDAY WILL
ONLY BE AROUND 20 ALONG WITH A BRISK WIND.

IT SHOULD STAY COLD FOR THE REST OF THE WEEK BUT THE LAKE EFFECT
SNOWS SHOULD BECOME LIGHTER.  TEMPERATURES SHOULD MODERATE INTO
MONDAY...BUT IT WILL COME WITH ANOTHER CHANCE OF SNOW.

&&

.UPDATE...
ISSUED AT 1056 AM EST TUE FEB 9 2016

I ENDED UP UPGRADING MOST OF THE LAKESHORE TO A WARNING AND
EXPANDED THE ADVISORY TO INCLUDE KALAMAZOO.

GIVEN THE LONG DURATION OF A NORTH NORTHWEST FLOW...LONG
FETCH...SATURATED DGZ AND MIXING HEIGHTS TAPING INTO THE 30 TO 35
KNOT WINDS...FEEL THAT THIS COULD END UP MORE OF A HIGHER IMPACT
EVENT NEAR THE LAKESHORE. SOME MESOSCALE MODELS NOW TRY TO
GENERATE MORE THAN A INCH OF QPF BY THU MORNING. WITH FAVORABLE
RATIOS...MUCH OF THE LAKESHORE SHOULD SEE MORE THAN A FOOT. I DID
MOVE UP THE START TIME OF THE EVENT AS THE SNOW BANDS WERE ALREADY
DEVELOPING SO INCREASING IMPACTS ARE EXPECTED THROUGH THE
AFTERNOON. WILL NEED TO MONITOR KALAMAZOO COUNTY CLOSELY AS THE
WESTERN END OF THE COUNTY MAY END UP WITH SOME HIGHER IMPACTS.

FOR NOW OUR EASTERN COUNTIES ARE ON THE WESTERN EDGE OF THE
STEADIER SNOW. WITH THE LOW EXPECTED TO TRACK SLOWLY EAST...WILL
NOT GO WITH HEADLINES THERE FOR THIS AFTERNOON.

&&

.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 256 AM EST TUE FEB 9 2016

LAKE EFFECT SNOWS WILL INCREASE TODAY.  THIS APPEARS TO BE A
DOMINATE BAND SET UP WHICH COULD BRING DOUBLE DIGIT SNOWFALL BEFORE
ITS DIMINISHES INTO THURSDAY MORNING.

THE COLDER H8 AIR ARRIVES TOWARD MID DAY TODAY WHEN THE LAKE EFFECT
SNOW WILL RAMP UP.  WILL LEAVE THE HEADLINE AS IS...STARTING AT
4PM...BUT THE STEADIER SNOWS COULD KICK IN SHORTLY AFTER NOON.  THE
MAIN THING IS THAT THE WORD IS OUT.

WITH H8 TEMPS OF -16C MOVING IN THIS AFTERNOON THE LAKE WILL BEGIN
TO LIGHT UP.  MOISTEN DEPTH IS SOLID WITH INVERSION LEVELS AT OR
ABOVE 8K FEET THIS AFTERNOON AND INTO TONIGHT.  THE PEAK OF THE LAKE
EFFECT SHOULD BE FROM ROUGHLY NOON TODAY THROUGH NOON WEDNESDAY WHEN
THERE IS LITTLE TO INHIBIT INTENSE SNOW BANDS.

THE MAIN CONCERN WITH THIS EVENT IS THAT MEAN CLOUD LAYER WINDS
APPEAR TO STAY ROCK SOLID...FROM 330-340 TODAY ALL THE WAY INTO
EARLY THURSDAY. THIS POINTS TOWARD DOMINATE BANDS THAT WON/T WAVER
MUCH. SIX-PLUS INCHES CERTAINLY LIKELY...WITH ISOLATED TWELVE INCH
REPORTS POSSIBLE BY THURSDAY MORNING.

ALONG WITH THIS...WINDS WILL GUST TO AROUND 35 MPH AT TIMES OVER THE
LAKESHORE COUNTIES CREATING BLOWING AND DRIFTING SNOW.  THIS WILL
REDUCE VISIBILITIES TO NEAR ZERO AT TIME.  THE TIMING OF THE
STRONGEST WINDS SHOULD COINCIDE WITH THE STEADIEST SNOWS...ROUGHLY
NOON TODAY THROUGH NOON THURSDAY.  IT IS NOT OUT OF THE QUESTION WE
MAY NEED TO BUMP SOME OF THE LAKESHORE INTO A WINTER STORM
WARNING...BUT WE WILL WAIT TO SEE HOW THIS EVOLVES INTO LATE TODAY.

FURTHER INLAND AREAS WILL ALSO SEE PERIODS OF SNOW THROUGH TONIGHT
AS THE UPPER LOW  OVER NW OHIO KEEPS DEEP MOISTURE OVER THE REGION.
A SHORT WAVE PIVOTING AROUND THE LOW MOVES IN TONIGHT FOR WIDESPREAD
SNOW.  EXPECTING A GENERAL 1-3 INCHES THROUGH TONIGHT.  INLAND SNOWS
SHOULD DIMINISH THROUGH WEDNESDAY...WITH MOST SNOW LINGERING ONLY
OVER THE LAKESHORE INTO WEDNESDAY NIGHT.

.LONG TERM...(THURSDAY NIGHT THROUGH MONDAY)
ISSUED AT 256 AM EST TUE FEB 9 2016

SNOW AND COLD WILL CONTINUE THROUGH THE LONG TERM. THE SNOW WILL
COME FROM A SEVERAL DIFFERENT METHODS...WHILE THE COLD WILL BE
PREVALENT AND LIKELY SOME OF THE COLDEST WE/VE SEEN THIS WINTER.

THURSDAY NIGHT...THE ARCTIC FRONT WILL BE APPROACHING FROM THE
NORTH WHICH WILL SPREAD MOISTURE BACK INTO AN UNSTABLE LAKE
ENVIRONMENT. EXPECT LAKE EFFECT TO PICK BACK UP AGAIN THURSDAY
NIGHT AFTER A LULL ON THURSDAY. SOME LIGHT ACCUMS EXPECTED TOWARDS
THE LAKESHORE.

ON FRIDAY...THE ARCTIC FRONT WILL SWEEP THROUGH THE FORECAST AREA
AND BRING SOME LIGHT SNOW AREA WIDE. ACCUMULATIONS INLAND WILL BE ON
THE LIGHT SIDE...AROUND AN INCH OR LESS. TOWARDS THE LAKE...THE
ACCUMULATIONS WILL BE A BIT MORE ON THE ORDER OF 1-3 INCHES
POTENTIALLY. LAKE EFFECT SNOW WILL CONTINUE ACROSS WESTERN LOWER MI
ON FRIDAY NIGHT AS THE ARCTIC AIR POURS IN. 850MB TEMPS WILL DROP TO
NEAR -26C SATURDAY AT 12Z. TEMPERATURES WILL NOT MAKE IT OUT OF THE
SINGLE DIGITS IN SOME SPOTS FOR HIGHS ON SATURDAY WHICH WILL BE MORE
THAN 20 DEGREES BELOW SEASONAL NORMS. HIGH PRESSURE WILL BRING
MAINLY COLD AND DRY CONDITIONS ON SATURDAY WITH THE LAKE EFFECT
DIMINISHING IN THE LIGHT FLOW.

SUNDAY INTO MONDAY THE MODELS BRING A SURFACE LOW INTO THE GREAT
LAKES REGION. THE GFS AND ECMWF HANDLE THIS SYSTEM DIFFERENTLY. AT
THIS POINT HAVE CHANCE POPS 30-40 PCT TO ACCOUNT FOR THE POSSIBILITY
OF SNOW. NOT CONFIDENT HOW THE SUN/MON LOW WILL PLAY OUT AT THIS
POINT THOUGH.

BOTTOM LINE...COLD WILL BE THE MAIN STORY IN THE EXTENDED WITH POOR
TRAVEL CONDITIONS TOWARDS THE LAKESHORE. SNOW PACKED AND SLIPPERY
ROADS EXPECTED IN THE LAKE SNOW BELTS GIVEN THE VERY COLD
CONDITIONS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1244 PM EST TUE FEB 9 2016

LAKE EFFECT SNOW SHOWERS ARE IN THE PROCESS OF STARTING TO RAMP UP
EARLY THIS AFTERNOON AS COLDER AIR IS MOVING IN. THE GENERAL FLOW
IS EXPECTED TO BE MAINLY FROM THE NNW THROUGH THE FCST PERIOD.
MVFR CONDITIONS CAN BE EXPECTED AT ALL TERMINALS WITH AT LEAST THE
LAKE EFFECT CLOUD COVER IN PLACE.

WE EXPECT THAT THE MOST INTENSE BANDS WILL LIKELY STAY WEST OF
ALL OF THE TERMINALS. KMKG AND KAZO WILL NOT BE FAR AWAY FROM SOME
OF THE BANDS...AND COULD SEE SOME LOCALIZED IFR AFFECT THE
TERMINAL AT TIMES. MVFR WILL BE PREDOMINATE AND THE BRIEF AND
SPORADIC CHCS AT IFR ARE TOO UNCERTAIN DUE TO THE SMALL SCALE OF
THE BANDS.

WIND GUSTS WILL DIMINISH THIS EVENING...BUT WILL LIKELY PICK UP
AGAIN LATE WED MORNING. LIGHT SNOW SHOWERS MAY NOT REACH INLAND
AREAS AS MUCH OVERNIGHT...BUT WILL RETURN THERE DURING THE
DAYLIGHT HOURS.

&&

.MARINE...
ISSUED AT 330 AM EST TUE FEB 9 2016

WILL BUMP THE AREAS NORTH OF WHITEHALL INTO A GALE WARNING.  THIS IS
A LOW END GALE...BUT WINDS INCREASE TO GALE FORCE LATE THIS
AFTERNOON AND SHOULD CONTINUE INTO WED MORNING.  FREEZING SPRAY WILL
ALSO BE ON THE MODERATE SIDE FOR MUCH OF THE NEARSHORE WATERS THIS
AFTERNOON THROUGH WED EVENING


&&

.HYDROLOGY...
ISSUED AT 1200 PM EST MON FEB 8 2016

COLDER TEMPERATURES (AS OPPOSED TO PRECIPITATION) WILL BE THE
HIGHLIGHT OF THE UPCOMING WEEK. DAYTIME HIGHS WILL CONSISTENTLY BE
BELOW FREEZING WITH NIGHTTIME TEMPERATURES INTO THE TEENS... AND
EVENTUALLY INTO THE SINGLE DIGITS BY THE END OF THE WEEK. STREAMS
AND RIVERS CONTINUE TO RUN HIGH. FORECAST TEMPERATURES AND HIGHER
RIVERS MAY CREATE SOME CONCERNS IN REGARDS TO ICE BUILD UP.
IN THE EVENT OF ICE FORMATION...FLUCTUATIONS COULD RESULT THROUGH
THE NEXT SEVERAL DAYS...POSSIBLY SENDING SOME LOCATIONS NEAR OR
OVER BANKFULL.

THE POSITIVE NOTE IS THAT PRECIPITATION OVER THE NEXT SEVERAL
DAYS WILL COME IN PERIODIC EPISODES. THE GREATEST TOTALS WILL
FAVOR LAKESHORE COUNTIES AND WILL BE IN THE FORM OF SNOW. FREEZING
TEMPERATURES WILL MINIMIZE RISK DUE TO RUNOFF...LIMITING THE RISK
MAINLY TO ICE JAM POTENTIAL.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...WINTER STORM WARNING UNTIL 10 AM EST THURSDAY FOR MIZ037-043-056-
     064-071.

     WINTER WEATHER ADVISORY UNTIL 10 AM EST THURSDAY FOR MIZ038-050-
     072.

LM...GALE WARNING UNTIL 10 AM EST WEDNESDAY FOR LMZ848-849.

     SMALL CRAFT ADVISORY UNTIL 7 PM EST WEDNESDAY FOR LMZ844>847.

&&

$$

UPDATE...MJS
SYNOPSIS...JK
SHORT TERM...JK
LONG TERM...DUKE
AVIATION...NJJ
HYDROLOGY...JAM
MARINE...JK


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