Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 071150
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
650 AM EST SUN FEB 7 2016

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 325 AM EST SUN FEB 7 2016

A LOW PRESSURE SYSTEM WILL MOVE SOUTHEAST INTO THE NORTHERN GREAT
LAKES REGION TODAY AND BRING POTENTIAL FOR A FEW SPRINKLES OR
FLURRIES THIS AFTERNOON. A FEW FLURRIES ARE ANTICIPATED TONIGHT
FOLLOWED BY A FEW LIGHT SNOW SHOWERS OR FLURRIES MONDAY. IT WILL
TURN MUCH COLDER TUESDAY THROUGH THE REST OF THE WEEK WITH
ACCUMULATING LAKE EFFECT SNOW AND POTENTIAL FOR HAZARDOUS TRAVEL
CONDITIONS TO DEVELOP.

&&

.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 325 AM EST SUN FEB 7 2016

OUR PRIMARY SHORT TERM FCST CHALLENGE IS TO DETERMINE POTENTIAL
FOR ACCUMULATING LAKE EFFECT SNOW MONDAY NIGHT AND TUESDAY
PARTICULARLY NEAR TO WEST OF US-131.

LOW PRESSURE MOVING INTO THE NORTHERN GREAT LAKES REGION WILL
BRING NOTHING MORE THAN A FEW SPRINKLES LATER TODAY NEAR TO SOUTH
OF I-96 AND A FEW FLURRIES FURTHER NORTH. MOST PCPN WITH THIS
SYSTEM WILL STAY WELL NORTH OF OUR FCST AREA. MAX TEMPS TODAY WILL
REACH THE UPPER 30S NORTH TO LOWER 40S SOUTH.

A FEW FLURRIES ARE ANTICIPATED TONIGHT BUT NOTHING MORE THAN THAT
IS EXPECTED AS SOME MID LEVEL DRYING OCCURS. A FEW LIGHT SNOW
SHOWERS ARE ANTICIPATED MONDAY AS SOME DEEPER MOISTURE BEGINS TO
MOVE IN ON THE BACK SIDE OF THE SYSTEM.

SNOW SHOWERS WILL GRADUALLY INCREASE MONDAY NIGHT WITH DEEP
MOISTURE IN PLACE AND AS H8 TEMPS FALL TO AROUND -10 TO -12 C BY
12Z TUE. THIS IN CONJUNCTION WITH TEMPS FALL INTO THE MID TO UPPER
20S BY DAYBREAK TUESDAY WILL LIKELY RESULT IN SOME SLICK SPOTS ON
AREA ROADS.

THE BEST CHANCE FOR ACCUMULATING SNOW IN THE SHORT TERM FCST
PERIOD WILL COME TUESDAY AS H8 TEMPS CONTINUE TO FALL TO AROUND
-13 TO -14 C BY 00Z WED AND WITH DEEP MOISTURE AND A SATURATED
DGZ. OUR WNW TO NW FLOW SNOW BELT REGIONS ARE MOST FAVORED FOR
A FEW INCHES OF SNOW PARTICULARLY NEAR TO WEST OF US-131. THIS
WILL RESULT IN POTENTIALLY HAZARDOUS TRAVEL CONDITIONS WITH TEMPS
ONLY REACHING THE 20S TUESDAY.

.LONG TERM...(TUESDAY NIGHT THROUGH SATURDAY)
ISSUED AT 325 AM EST SUN FEB 7 2016

THERE IS LITTLE QUESTION WED THROUGH SUN WILL BE COLDER THAN NORMAL
ACROSS THE AREA. HOWEVER THERE IS A SIGNIFICANT QUESTION AS TO JUST
HOW FAR BELOW NORMAL WE GET FRI INTO SUN AS THE ECMWF CONTINUES TO
BE MUCH COLDER THAN THE GFS IN THAT TIME FRAME.

THE OTHER ISSUE WE NEED TO CONSIDER IS LAKE EFFECT SNOWFALL THROUGH
THIS TIME PERIOD. THIS WILL BE A NORTHWEST FLOW SET UP FROM TUE
NIGHT THROUGH EARLY THURSDAY MORNING. MODEL SOUNDING LOOK VERY
IMPRESSIVE FOR SNOW ALONG THE LAKE SHORE... ESPECIALLY FROM HOLLAND
SOUTH TO SOUTH HAVEN.  INVERSION HEIGHTS ARE NEAR 10000 FT AND THE
GFS SHOWS STRONG LIFT IN THE DGZ INTO EARLY THURSDAY MORNING. THE
MOISTURE DEEP IS IMPRESSIVE TOO... WITH THE 100 PCT OR GREAT (WITH
RESPECT TO ICE RH) UP TO 18000 FT AT MIDNIGHT TUESDAY NIGHT AND
ABOVE 10000 FT THROUGH 7 AM THURSDAY. I HAVE TO BELIEVE...EVEN WITH
THE AIR AS COLD AS IT IS...LOCATIONS NEAR US-31 SOUTH OF HOLLAND
WILL SEE AT LEAST A FOOT OF SNOW FROM THIS EVENT BETWEEN TUE NIGHT
AND THURSDAY MORNING. ACTUALLY WITH THE HELP OF THE LAKE SUPERIOR
CONNECTION PARTS OF MASON...OCEANIA AND MAYBE EVEN LAKE COUNTY MAY
ALSO HAVE A SIGNIFICANT AMOUNT OF SNOW FROM THIS EVENT. HELPING THE
CAUSE IS A CLOSED UPPER LOW THAT DOES NOT MOVE OUT OF THE ARE UNTIL
WED AFTERNOON. INLAND OF US-31 THERE WOULD BE VERY LIMITED SNOW.

THE UPPER JET CROSSES LOWER MICHIGAN THURSDAY AFTERNOON...THAT WILL
LOWER INVERSION HEIGHTS AND SIGNIFICANTLY WEAKEN THE SNOW SHOWERS.
HOWEVER ON FRIDAY THE NEXT COLD FRONT COME THROUGH. THAT BRINGS
INVASION HEIGHTS BACK UP AND MORE SNOW IS EXPECTED. THIS WOULD COVER
THE CWA AS THIS IS A FRONTAL SYSTEM MOVING THROUGH.

SO THEN COMES OUR BIG QUESTION. WHAT HAPPENS OVER THE WEEKEND?  THE
ECMWF...THE PARALLEL ECMWF...THE ECMWF ENSEMBLES AND SEVERAL RUNS IN
A ROW OF THE THOSE MODELS SHOW THE COLDEST AIR OF THE SEASON MOVING
IN WITH 850 TEMPS FALLING TO NEAR -25C OVER GRR.  MEANWHILE THE GFS
ONLY BRINGS THE EDGE OF THAT COLD AIR INTO THE AREA.  LOOKING AT
UPPER LEVELS THE ECMWF HAS A MUCH STRONGER SYSTEM COMING SOUTH FROM
NEAR THE NORTH POLE EARLY TUESDAY...OVER HUDSON BAY THURSDAY TO JUST
NORTH OF LAKE HURON (A CLOSED UPPER LOW BY THEN) FRIDAY AFTERNOON.
THE GFS IS WEAKER WITH THIS SYSTEM AND HAS IT CLOSER TO JAMES BAY.
GIVEN THE GFS IS SIGNIFICANT ISSUES WITH ARCTIC SHORT WAVES AND THE
CONSISTENCY OF THE ECMWF I AM FAVORING THE ECMWF. IN OUR FORECAST WE
HAVE A 50/50 MIX FOR OUR HIGH AND LOW TEMPERATURES FOR NOW. IF THE
ECMWF IS CORRECT HIGHS WOULD BE CLOSER TO 10 DEGREES SATURDAY.
LOWS WOULD BE NEAR 10 BELOW OVER OUR NORTHERN CWA. IF THE GFS WERE
TO BE CORRECT HIGHS WOULD BE IN THE MID 20S. AS FOR SNOW WITH THIS
WINDS WILL BE NORTH TO NORTH NORTHEAST SO THERE WOULD BE LITTLE IN
THE WAY OF LAKE EFFECT OVER THE WEEKEND.

SO...THE BOTTOM LINE IS WINTER COMES BACK AND HANGS IN THERE THROUGH
THIS COMING WEEKEND.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 650 AM EST SUN FEB 7 2016

CURRENTLY (1145Z) VFR CIGS/VSBY PREVAIL ACROSS OUR TAF SITES AND I
EXPECT THAT TO REMAIN THE CASE INTO LATE AFTERNOON. IT WILL GET
BREEZY AS SOUTHWEST WINDS WILL INCREASE TO 15 TO 25 KNOTS BY 15Z
OR SO. AN AREA OF LOW CLOUDS BEHIND THE COLD FRONT WILL REACH
SOUTHWEST LOWER MICHIGAN LATE THIS AFTERNOON BUT AT THIS POINT IT
SEEMS ONLY MKG AND GRR WILL SEE MVFR CIGS FROM THIS DURING THE
LATE AFTERNOON. ALL OTHER TAF SITES SHOULD REMAIN VFR.

AFTER THE SUN SETS AND THE COLD FRONT HAS COME THROUGH THE AREA
WINDS WILL BECOME LIGHT AND THERE WILL BE ENOUGH LOW LEVEL
MOISTURE THAT FOG MAY BECOME AN ISSUE. THE NAM12 SHOWS NEARLY THE
ENTIRE CWA BELOW 1/4 MILE BY 06Z. I WAS MORE CONSERVATIVE IN OUR
TAFS BUT THIS IS SOMETHING TO WATCH FOR.

THE PRECIPITATION ON OUR RADAR MOSAIC IS NEARLY ALL ALOFT SO I
HAVE NO PRECIPITATION IN OUR TAFS TODAY. I DO BRING SOME LIGHT
SNOW INTO THE MKG AND GRR TAFS TOWARD MONDAY MORNING (10Z).

C

&&

.MARINE...
ISSUED AT 325 AM EST SUN FEB 7 2016

A SMALL CRAFT ADVISORY REMAINS IN EFFECT UNTIL 7 PM THIS EVENING.
SOUTH TO SW WINDS OF UP TO 15 TO 25 KTS WILL RESULT IN 3 TO 5 FOOT
WAVE HEIGHTS. WINDS AND WAVES WILL SUBSIDE SOMEWHAT TONIGHT.


&&

.HYDROLOGY...
ISSUED AT 132 PM EST SAT FEB 6 2016

THE GRAND RIVER AT IONIA IS ON TRACK TO FALL BELOW BANKFULL
TONIGHT OR SUNDAY MORNING. THE RIVER AT MAPLE RAPIDS HAS BEGUN
ITS SLOW RECESSION. COLDER TEMPERATURES AFTER MONDAY WILL CAUSE
RIVER ICE TO REDEVELOP... SO WE WILL HAVE TO WATCH FOR RIVER LEVEL
FLUCTUATIONS THEN.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 7 PM EST THIS EVENING FOR LMZ844>849.

&&

$$

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


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