Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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783
FXUS63 KGRR 071743
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1243 PM 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.

&&

.UPDATE...
ISSUED AT 1112 AM EST SUN FEB 7 2016

I UPDATED THE FORECAST TO FEATURE HIGH TEMPERATURES SEVERAL
DEGREES WARMER THAN FORECASTED FOR TODAY. ALREADY SOME 40S
SHOWING UP IN THE OBSERVATIONS.

&&

.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 SOUNDINGS 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 DEPTH IS IMPRESSIVE TOO... WITH 100 PCT OR GREATER (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...OCEANA 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 AREA 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
INVERSION 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 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1243 PM EST SUN FEB 7 2016

MID CLOUDS COMING THROUGH EARLY THIS AFTERNOON ARE LIKELY NOT
PRODUCING MUCH IMPACT ACROSS THE AREA. WINDS HAVE BEEN A LITTLE
GUSTY TO ABOUT 25 KNOTS OR SO...AND THIS WILL CONTINUE THROUGH THE
AFTERNOON BEFORE DIMINISHING THIS EVENING.

WE WILL SEE SOME LOWER CLOUDS DEVELOP/MOVE IN FROM THE WEST THIS
EVENING. CLOUDS WILL REMAIN VFR FOR A BIT...AND THEN TREND TOWARD
MVFR AROUND 00Z AND A LITTLE LATER TO THE EAST. THE MVFR CIGS WILL
REMAIN FAIRLY STEADY THROUGH MUCH OF THE NIGHT. WE WILL LIKELY SEE
VSBYS DROP TO MVFR ALSO TOWARD SUNRISE MON AND EVEN TO IFR AT THE
WRN TERMINALS IN SOME FOG.

SOME SNOW SHOWERS WILL BECOME POSSIBLE TOO AT THAT TIME...
ALTHOUGH THE SNOW SHOWERS WILL NOT BE THAT STRONG. THESE
CONDITIONS WILL CONTINUE THROUGH THE MORNING...WITH SOME POSSIBLE
IMPROVEMENT TOWARD OR AFTER THE END OF THE FCST PERIOD.

&&

.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 1216 PM EST SUN FEB 7 2016

THE RIVER AT MAPLE RAPIDS IS EXPECTED TO FALL BELOW BANKFULL BY
LATE TUESDAY OR EARLY WEDNESDAY. COLD TEMPERATURES THIS WEEK WILL
CAUSE ICE TO REDEVELOP... SO WE WILL HAVE TO WATCH FOR RIVER
LEVEL FLUCTUATIONS IF FREEZE UP ICE JAMS OCCUR. WITH MANY RIVERS
CURRENTLY RUNNING HIGHER THAN SEASONAL NORMALS... A FEW RIVERS
COULD RISE OUT OF THEIR BANKS AGAIN.

&&

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

&&

$$

UPDATE...MJS
SYNOPSIS...LAURENS
SHORT TERM...LAURENS
LONG TERM...WDM
AVIATION...NJJ
HYDROLOGY...CAS
MARINE...LAURENS



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