Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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707
FXUS63 KGRR 021144
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
644 AM EST TUE FEB 2 2016

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 315 AM EST TUE FEB 2 2016

A STORM SYSTEM WILL COME OUT OF THE PLAINS TODAY AND BRING A GOOD
DEAL OF PRECIPITATION TO THE AREA BEGINNING THIS AFTERNOON AND
LASTING INTO THE EVENING HOURS. THE PRECIPITATION WILL START OUT AS
MAINLY RAIN ALONG AND SOUTH OF I-96...WHILE AREAS NORTH WILL SEE
PRECIPITATION START OUT AS SNOW AND TRANSITION THROUGH A MIX OF
SLEET AND POSSIBLY FREEZING RAIN BEFORE CHANGING OVER TO ALL RAIN IN
THE EVENING.

PRECIPITATION WILL THEN CHANGE FROM RAIN WEDNESDAY MORNING TO SNOW
SHOWERS BY THE END OF THE DAY AS COLDER AIR FILTERS IN. LAKE EFFECT
SNOW SHOWERS WILL REMAIN POSSIBLE INTO THURSDAY BEFORE THEY DIMINISH
A BIT.

&&

.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 315 AM EST TUE FEB 2 2016

WE WILL BE HOLDING ON TO THE WINTER WEATHER ADVISORY UP ACROSS THE
U.S.-10 CORRIDOR COUNTIES WITH THIS FCST PACKAGE. THIS REMAINS FOR A
COMBINATION OF LIGHT SNOW AMOUNTS...AND A WINTRY MIX OF PCPN BEFORE
THINGS CHANGE OVER TO RAIN TONIGHT.

THE TREND FOR THE DELAY IN PCPN ARRIVING INTO THE CWFA TODAY IS
GOING TO ALLOW FOR A LITTLE MORE WARMING TO TAKE PLACE BEFORE PCPN
MAKES IT INTO THE AREA. THIS IS GOING TO PRETTY MUCH TAKE OUT LEGIT
SNOW CHANCES ALONG AND SOUTH OF I-96 EXCEPT FOR SOME LIGHT PCPN THAT
MIGHT FLOAT THROUGH OUT AHEAD OF THE MAIN PCPN THAT WILL MOVE IN
AROUND OR AFTER 18Z TODAY.

PCPN WILL BREAK OUT THIS AFTERNOON AS THE STRONG LLJ ARRIVES AND
PROVIDES SIGNIFICANT MOISTURE TRANSPORT. THIS STRONG LLJ WILL ALSO
SUPPORT SOME WINDS UP TO AROUND 40 MPH AT THE SFC. FCST SOUNDINGS
INDICATE THAT SOME SNOW OR SLEET WILL BE THE INITIAL P-TYPE. AS
TEMPS ALOFT GO ABOVE FREEZING BY 03Z...PCPN WILL CHANGE TO RAIN
EVERYWHERE. SOME LOCATIONS ALONG U.S.-10 COULD SEE A LITTLE FREEZING
RAIN WITH EVAP COOLING BRINGING/KEEPING TEMPS AROUND FREEZING FOR A
LITTLE WHILE BEFORE PCPN GOES TO ALL RAIN. THIS WOULD BE SHORT IN
DURATION...WITH ANY ICE ACCUMS REMAINING LESS THAN A TENTH OF AN
INCH.

THUNDER REMAINS POSSIBLE ACROSS THE CWFA FROM LATE THIS AFTERNOON
INTO EARLY THIS EVENING. ELEVATED INSTABILITY IS PRESENT AHEAD OF
THE FRONT...AND THE DRY SLOT PUNCHING IN WILL ALSO SUPPORT A CHC OF
THUNDER.

THE RAIN WILL COME TO AN END...AND PCPN WILL TRANSITION TO DRIZZLE
FOR MOST OF THE REST OF THE NIGHT TONIGHT. WE WILL HAVE TO WAIT
UNTIL WED MORNING BEFORE WE SEE PCPN MOVE BACK IN VIA THE
DEFORMATION ZONE WITH THE UPPER LOW. THE PCPN WOULD START OUT AS
RAIN AS THE MELTING LAYER REMAINS THICK ENOUGH. WE WILL SEE PCPN
THEN CHANGE OVER TO SNOW AS THE COLDER AIR FILTERS IN WITH THE LOW.

WE WILL SEE SNOW SHOWERS THEN PERSIST FROM LATE WED AFTERNOON INTO
THE FIRST HALF OF THE DAY ON THU. H850 TEMPS OF AROUND -10 TO -14C
WILL BE MOVING IN DURING THIS TIME FRAME. WE WILL BE SEEING
INVERSION HEIGHTS DROPPING AFTER WED MORNING AS THE UPPER LOW MOVES
AWAY. INVERSION HEIGHTS OF 4-5K FT SHOULD LIMIT LAKE EFFECT ENOUGH
THAT SIGNIFICANT AMOUNTS WILL NOT BE EXPECTED.



.LONG TERM...(THURSDAY NIGHT THROUGH MONDAY)
ISSUED AT 315 AM EST TUE FEB 2 2016

THE LONG TERM PERIOD STARTS OFF WITH A WEAK 700 MB WAVE TRACKING
THROUGH THE REGION THURSDAY NIGHT.  THE AIRMASS IS STILL COLD ENOUGH
FOR LAKE EFFECT.  LOW LEVEL CONVERGENCE ASSOCIATED WITH THE PASSAGE
OF THIS WAVE WILL SUPPORT SNOW SHOWERS...ESPECIALLY WEST OF A GRAND
RAPIDS TO BIG RAPIDS LINE.  MINOR ACCUMULATIONS POSSIBLE.

A LULL IN THE SNOW SHOWER ACTIVITY LOOKS LIKELY FOR FRIDAY...BUT
THEN ANOTHER WAVE ARRIVES FOR FRIDAY NIGHT.  TRENDS SUGGEST THAT IT
WILL BE WEAKER AND FURTHER NORTH WITH ITS TRACK.  FOR MY CWA...THIS
MEANS THE BEST POTENTIAL FOR SNOW SHOWERS WILL BE  NORTH OF A
MUSKEGON TO GRAND RAPIDS LINE.  ONCE AGAIN SOME MINOR ACCUMULATIONS
LOOK POSSIBLE...ESPECIALLY FROM LUDINGTON TO NEAR IRONS AND BALDWIN.

ARCTIC AIR ARRIVES MONDAY INTO TUESDAY.  THE FRONT OUT AHEAD OF IT
WILL FEATURE SOME SHOWERS POSSIBLY SUNDAY BUT MORE LIKELY SUNDAY
NIGHT OR MONDAY.  THE GFS WOULD SUPPORT RAIN SHOWERS IF THEY OCCUR
ON SUNDAY.   THE CURRENT FORECAST OF SNOW SHOWERS IS STILL SUPPORTED
BY THE HIGH RES EURO WHICH IS WHAT I WILL MAINTAIN IN THE GRIDS.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 629 AM EST TUE FEB 2 2016

MULTIPLE AVIATION HAZARDS INTO TONIGHT. INITIALLY MVFR CONDITIONS
LIKELY TO GO TO VFR THIS MORNING. THE WIND WILL INCREASE STEADILY
AS THE STORM APPROACHES INTO THIS AFTERNOON WITH EASTERLY SURFACE
WINDS THAT COULD GUST OVER 35 KNOTS. THIS COULD LEAD TO POSSIBLE
WIND SHEAR AS THE FLOW UP AROUND 2K FEET WILL BE AROUND 50 KNOTS
AND OUT OF THE SOUTHEAST SHIFTING TO THE SOUTH THIS EVENING.

INSTABILITY MOVES IN FROM THE SOUTH GENERALLY AFTER 22Z.
BASICALLY ITS THE AREA OF THUNDERSTORMS THAT IS CURRENTLY OVER IN
MO...THAT HEADS OUR WAY.

AS THE RAIN MOVES IN...THE ONSET COULD FEATURE A BRIEF PERIOD OF
SLEET OR ZR. NO CONFIDENT THAT WILL HAPPEN A THE TAF SITES TO
INCLUDE IT IN THE FORECAST...BUT ICING IN THE CLOUDS IS LIKELY TO
OCCUR FOR THE FIRST FEW HOURS OF THE PRECIPITATION.

IFR POTENTIAL EXISTS...ESPECIALLY LATER THIS AFTERNOON AND EVENING
AS RAIN MOVES IN. SOMETIMES IN THESE WINDY EVENTS THE IFR AND
LOWER CONDITIONS DEVELOP SLOWER THAN EXPECTED.


&&

.MARINE...
ISSUED AT 315 AM EST TUE FEB 2 2016

WE WILL BE LEAVING THE GALE WARNING OUT AS IS FOR TODAY. WINDS WILL
RAMP UP THIS AFTERNOON AND CONTINUE INTO THE EARLY EVENING HOURS
BEFORE COMING DOWN. WAVES WILL NOT BE AS BIG AS POSSIBLE DUE TO THE
OFFSHORE COMPONENT TO THE WIND. THERE IS A CHANCE OF ANOTHER ROUND
OF GALES ON WED...AS THE MAIN LOW FINALLY PULLS OUT. WE WILL KEEP
THINGS SIMPLE FOR NOW...AND ADDRESS THAT LATER.


&&

.HYDROLOGY...
ISSUED AT 156 PM EST MON FEB 1 2016

MINOR FLOODING IS POSSIBLE LATER THIS WEEK... ESPECIALLY IN
LOWLAND AREAS NEAR RIVERS. SOME RIVERS MAY EXCEED BANKFULL DUE TO
SNOW MELT AND A STORM TUESDAY INTO WEDNESDAY. STORM TOTAL
PRECIPITATION OF 0.50-1.00 INCHES IS POSSIBLE. PRECIPITATION IS
STILL EXPECTED TO BE A WINTRY MIX OR PLAIN RAIN. RIVER LEVEL RISES
ARE ESPECIALLY LIKELY FROM MIDWEEK THROUGH THE WEEKEND.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...WINTER WEATHER ADVISORY FROM 1 PM THIS AFTERNOON TO 1 AM EST
     WEDNESDAY FOR MIZ037>040.

LM...GALE WARNING FROM 10 AM THIS MORNING TO 7 PM EST THIS EVENING
     FOR LMZ844>849.

&&

$$

SYNOPSIS...NJJ
SHORT TERM...NJJ
LONG TERM...MJS
AVIATION...MJS
HYDROLOGY...63
MARINE...NJJ



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