Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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172
FXUS63 KGRR 122000
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
300 PM EST FRI FEB 12 2016

LATEST UPDATE...
SYNOPSIS/SHORT TERM/LONG TERM/MARINE

.SYNOPSIS...
ISSUED AT 300 PM EST FRI FEB 12 2016

THE PASSAGE OF AN ARCTIC FRONT THIS EVENING WILL BRING SOUTHWEST
MICHIGAN THE COLDEST WEEKEND OF THE WINTER. THE SNOW SHOWERS OVER
AREAS EAST OF US-131 WILL COME TO AN END THIS EVENING BUT LAKE
EFFECT SNOW SHOWERS WITH CONSIDERABLE BLOWING AND DRIFTING SNOW
ILL CONTINUE ALONG LAKE SHORE TONIGHT. SATURDAY POLAR HIGH PRESSURE
HEADS TO THE SOUTHERN GREAT LAKES. THAT WILL END THE BLOWING AND
DRIFTING SNOW ALONG THE LAKE SHORE BUT SNOW SHOWERS WILL CONTINUE
INTO TH EVENING. THE CENTER OF THE SURFACE HIGH WILL PASS SOUTH OF
MICHIGAN SATURDAY NIGHT. EVEN SO SKIES WILL CLEAR AND THAT WILL
BRING US THE COLDEST NIGHT OF THE WINTER. MOST LOCATIONS SHOULD
SEE LOW BELOW ZERO.

A STORM SYSTEM MOVES THROUGH THE GREAT LAKES SUNDAY NIGHT INTO
MONDAY BRINGING LIGHT SNOW AND MILDER TEMPERATURES TO THE AREA.
YET ANOTHER SYSTEM MAY BRING MORE LIGHT SNOW TUESDAY NIGHT AND
THAT WILL BE FOLLOWED BY MORE COLD AIR WITH LAKE EFFECT SNOW
SHOWERS. A BIG WARM UP FOLLOWS THAT FOR FOLLOWING WEEKEND.

&&

.SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT)
ISSUED AT 300 PM EST FRI FEB 12 2016

I HAVE MADE NO CHANGES TO ANY OF OUR HEADLINES AS OUR GOING
FORECAST LOOKS GREAT. WE WILL SEE THE LINE OF SNOW SHOWERS/SNOW
SQUALLS WITH THE ARCTIC FRONT CROSS THE AREA THIS EVENING AND IT
IS FOR THAT REASON I WILL CONTINUE THE WINTER WEATHER ADVISORY FOR
THE ROW OF COUNTIES INLAND FROM LAKE MICHIGAN. NEARLY EVERY
REPORTING STATION THAT HAS BEEN HIT BY THE LINE OF SNOW SHOWERS
AHEAD OF THE ARCTIC FRONT HAS SEEN 1/4SM +SN WITH GUSTY WINDS. THE
HIGH RESOLUTION MODLES CONITUNE TO BRING THIS BAND OF SNOW
SHOWERS CROSS I-96/I-196 AROUND 6 PM AND I-94 AROUND 8 PM. ONCE
THIS PASSES THE SNOW SHOWERS WILL END NEAR AND EAST OF US-131.

MEANWHILE ALONG THE LAKE SHORE...THEY TWO WILL HAVE THESE SNOW
SHOWER BUT FOR THOSE NEAR US-31 TO THE LAKE SHORE... IT IS ONLY
AFTER THE ARCTIC FRONT THAT HEAVY LAKE EFFECT SNOW BEGINS.
INVESION HEIGHT RISE TO NEARLY 10000 FT BETWEEN 00Z AND 06Z AND
THE DGZ IS STILL IN THE CLOUDS WITH CONSIDEDABLE LIFT. ALSO
THETA-E DECREASES WITH HEIGHT TO 8000 FT AND THERE IS NEARLY 300
J/KG OF MOST UNSTABLE CAPE ALONG THE LAKE SHORE BEHIND THE ARCTIC
FRONT. ALL THE HIGH RESOULTION MODELS SHOW OVER A 1/4 INCH OF QPF
FROM SOUTH HAVEN SOUTH TONIGHT. GIVEN ALL OF THIS I HAVE TO
BELIEVE WE WILL SEE A GOOD 4 TO 8 INCHES OVERNIGHT IN THE WARNING
COUNTIES NEAR AND WEST OF US-31. THOSE CLOSE TO US-131 WILL SEE
VERY LITTLE AFTER 10 PM. THE ADVIOSRY COUNTIES NEAR THE LAKE SHORE
WILL LIKELY SEE 2 TO 5 INCHES OVERNIGHT.

SATURDAY THIS ALL SLOWLY QUIETS DOWN AS SURFACE HIGH PRESSURE
MOVES TOWARD THE AREA DECREASING THE PRESSURE GRADIENT AND HENCE
THE SURFACE WIND. SINCE THE SUN IS GETTING STRONGER NOW AS IT IS
MID FEBRUARY... WE WILL SEE SURFACE HEATING CAUSE THE SNOW SHOWERS
TO SPREAD INLAND DURING THE DAY TIME HOURS OF SATURDAY.
ACCUMULATIONS WILL BE MOSLTY LESS THAN A HALF INCH EAST OF US-31.

SATURDAY NIGHT WITH THE HIGH MOVING ACROSS THE AREA WE WILL SEE A
LAND BREEZE SET UP AND THAT WILL CLEAR THE SKY NEARLY TO THE LAKE
SHORE. THAT WILL SET THE STAGE FOR THE COLDEST NIGTH OF WINTER.
WINDS WILL GO NEAR CALM AND EVEN THE WINDS IN THE BOUNDARY LAYER
WILL BE LESS THAN 10 KNOTS AFTER MIDNIGHT. A GREAT SET-UP FOR
VERY COLD TEMPERATURES. I WENT 5 DEGREES BELOW MOS ACROSS THE CWA
FOR LOW TEMPERATURES.

THE NEXT SYSTEM COMES IN FROM THE NORTHERN STREAM... IT IS A WARM
ADVECTION LIFT EVENT SO WE SHOULD SEE LIGHT SNOW ACROSS THE AREA
SUNDAY NIGHT. I PUT LIKELY POPS ACROSS THE AREA AFTER MIDNIGHT.
THIS WILL BE A LIGHT SNOW WITH MOST AREAS ONE TO TWO INCHES BY
SUNRISE MONDAY.



.LONG TERM...(MONDAY THROUGH FRIDAY)
ISSUED AT 300 PM EST FRI FEB 12 2016

A WEAK LOW PRESSURE SYSTEM WILL BRING A CHANCE OF LIGHT SNOW
MONDAY AND A FEW LIGHT SNOW SHOWERS AND FLURRIES MAY LINGER TUESDAY.
TEMPS WILL AVERAGE NEAR TO SLIGHTLY ABOVE NORMAL MONDAY AND TUESDAY
BEFORE SOME COLDER AIR MOVES IN FOR WEDNESDAY AND THURSDAY AS A SFC
HIGH PRESSURE RIDGE BUILDS IN.

IT IS NOTED THAT A CONSENSUS OF LATEST MEDIUM RANGE GUIDANCE
SUGGESTS THE GULF COAST SYSTEM MONDAY WILL STRENGTHEN SIGNIFICANTLY
AND TRACK NORTHEAST INTO THE MID ATLANTIC REGION TUESDAY. PCPN WITH
THIS SYSTEM SHOULD STAY WELL SE OF OUR AREA ACROSS OHIO AND FURTHER
EAST.

TEMPS SHOULD MODERATE TO ABOVE NORMAL BY LATE NEXT WEEK AS SOUTHERLY
FLOW WAA DEVELOPS ON THE BACK SIDE OF THE DEPARTING RIDGE. THERE IS
POTENTIAL FOR A MIX OF PCPN FRIDAY DUE TO ISENTROPIC UPGLIDE NORTH
OF A WARM FRONT THAT WILL LIKELY BE DRAPED ACROSS THE OHIO VALLEY
REGION BY THEN.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1106 AM EST FRI FEB 12 2016

A MIX OF MVFR... IFR AND LIFR CONDITIONS WILL CONTINUE THIS
AFTERNOON DUE TO SIGNIFICANTLY REDUCED VISBYS IN SNOW AND BLOWING
SNOW. AN ARCTIC COLD FRONT DROPPING DOWN FROM THE NORTH WILL BRING
A BRIEF PERIOD OF PREDOMINANTLY LIFR CONDITIONS LATE THIS
AFTERNOON AND EARLY EVENING DUE TO HEAVY SNOW AND BLOWING SNOW.

NW WINDS WILL GUST TO NEAR 25 KTS AT TIMES THIS AFTERNOON AND
EVENING BEFORE DIMINISHING A BIT LATE TONIGHT. LAKE EFFECT SNOW
SHOWERS LATE THIS EVENING AND OVERNIGHT WILL MAINLY AFFECT THE
KMKG AND PERHAPS THE KAZO TERMINALS WITH JUST SOME FLURRIES
ANTICIPATED FURTHER INLAND.

CONDITIONS OVERNIGHT THROUGH MIDDAY SATURDAY WILL GRADUALLY
IMPROVE TO MVFR THEN VFR WITH THE EXCEPTION OF KMKG AND KAZO WHERE
IFR/MVFR CONDITIONS WILL LINGER DUE TO NW FLOW LAKE EFFECT SNOW
SHOWERS. ANOTHER NW FLOW LAKE EFFECT SNOW BAND WITH A CONNECTION
TO LAKE SUPERIOR TOMORROW WILL STAY NORTH OF KGRR/KLAN.


&&

.MARINE...
ISSUED AT 300 PM EST FRI FEB 12 2016

NO CHANGES IN THE MARINE HEADLINES. GALES LOOK GOOD BEHIND THE
ARCTIC FRONT INTO EARLY TONIGHT. WITH LITTLE IN THE WAY OF ICE IN
THE NEAR SHORE... FREEZING SPRAY IS ASSURED... AND WITH THOSE SORT
OF WINDS AND TEMPATURES THE HEAVY FREEZING SPRAY IDEA LOOKS GREAT.
AGAIN... ALL OF THIS SHOULD SLOWLY IMPROVE SATURDAY AFTERNOON INTO
SATURDAY EVENING AS THE SURFACE HIGH MOVES TOWARD THE AREA.

&&

.HYDROLOGY...
ISSUED AT 1216 PM EST THU FEB 11 2016

NOT MUCH HAS CHANGED IN THE LAST 24 HOURS. THE DOWNWARD TREND
CONTINUES AT MAPLE RAPIDS...WHICH HAS ALLOWED US TO DROP THE
ADVISORY AT THAT LOCATION.

THIS MORNINGS OBSERVATIONS ON THE GRAND RIVER AT ROBINSON TWP SHOW
SMALL...THIN PIECES OF ICE FLOWING IN THE RIVER. A FEW RIVER
GAUGES THROUGHOUT SOUTHWEST LOWER MICHIGAN ARE BEGINNING TO SHOW
SIGNS OF BEING AFFECTED BY ICE. AT THIS POINT IT IS NOT AN ISSUE.
HOWEVER...TEMPERATURES WILL ONLY CONTINUE TO GET COLDER THROUGH
THE WEEKEND. THIS WILL SUPPORT ADDITIONAL ICE FORMATION THROUGH AT
LEAST SUNDAY MORNING WITH OVERNIGHT TEMPERATURES IN THE SINGLE
DIGITS. SOMETHING TO CONSIDER IS THAT WE ARE LATE IN THE WINTER
SEASON AND WATER TEMPERATURES ARE LOW ENOUGH THAT ICE DEVELOPMENT
COULD OCCUR FAIRLY QUICKLY WITH LONG PERIODS OF SUB-FREEZING AIR.

OVERALL PRECIPITATION AMOUNTS ARE STILL LOW THROUGH THE NEXT 7
DAYS. ASIDE FROM ANY LOCAL HEAVY LAKE EFFECT SNOWFALL THAT
OCCURS...OVERALL AMOUNTS WILL BE FAIRLY LIGHT. EVEN THIS WILL NOT
BE REALIZED UNTIL MELTING TAKES PLACE. THE MAIN CONCERN WILL BE
RIVER FLUCTUATION DUE TO ICE IN THE EVENT THAT THICK ICE DEVELOPS.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...WINTER STORM WARNING UNTIL 4 PM EST SATURDAY FOR MIZ064-071.

     WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR MIZ044-
     057-065.

     WINTER WEATHER ADVISORY UNTIL 4 PM EST SATURDAY FOR MIZ037-038-
     043-050-056-072.

LM...HEAVY FREEZING SPRAY WARNING FROM 7 PM THIS EVENING TO 7 AM EST
     SATURDAY FOR LMZ844>849.

     GALE WARNING UNTIL 7 AM EST SATURDAY FOR LMZ844>849.

&&

$$

SYNOPSIS...WDM
SHORT TERM...WDM
LONG TERM...LAURENS
AVIATION...LAURENS
HYDROLOGY...JAM
MARINE...WDM



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