Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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510
FXUS63 KGRR 100501
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1201 AM EST WED FEB 10 2016

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 253 PM EST TUE FEB 9 2016

A LOW PRESSURE SYSTEM EAST OF DETROIT WILL SHIFT SLOWLY EAST
TONIGHT AND WEDNESDAY. COLD AIR WRAPPING AROUND THIS DEPARTING
SYSTEM WILL GENERATE LOCALLY HEAVY SNOW SHOWERS MAINLY ALONG THE
LAKESHORE INTO THURSDAY. TEMPERATURES WILL FALL TO WELL BELOW
NORMAL VALUES AS THE ARCTIC AIRMASS SETTLES IN THROUGH THE END OF
THE WEEK.

&&

.SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT)
ISSUED AT 253 PM EST TUE FEB 9 2016

THE MAIN CHALLENGE IN THE SHORT TERM DEALS WITH THE IMPACTS
ASSOCIATED WITH THE FORECASTED SNOW INTO THURSDAY.

THE SNOW SHOWERS HAVE BEEN INCREASING THROUGH THE DAY TODAY AS
COLD AIR ADVECTION CONTINUES. IMPACTS ALREADY UNDERWAY WITH
SEVERAL SNOW BANDS CAUSING SLOW DOWNS NOTED ON INTERSTATE 196 AND
ROUTE 31. THE MOISTURE IS SHOWN TO DEEPEN UP THIS EVENING AND
THROUGH TONIGHT. IR SATELLITE IMAGERY SHOWS COLD CLOUD TOPS IN THE
UPPER PENINSULA...WHICH IS FORECASTED BY THE MODELS TO ARRIVE IN
SOUTHWEST LOWER MI TONIGHT. GIVEN THE PERSISTENT CONVERGENT NORTH
TO NORTHWEST LOW LEVEL FLOW...STEEPENING LOW LEVEL LAPSE RATES
OVER THE LAKE AND DEEP MOISTURE...THE SNOW SHOWERS ARE EXPECTED TO
STRENGTHEN. THE FLOW FAVORS THE REGION FROM HOLLAND TO AROUND
SOUTH HAVEN...AND ALSO THE AREA NORTH OF WHITEHALL FOR THE
HEAVIEST SNOW. THE LOW WATER CONTENT OF THE SNOW COUPLED WITH WIND
GUSTS OVER 30 MPH...SUPPORTS BLOWING SNOW. THUS THE POTENTIAL
EXISTS FOR HIGH IMPACTS AND POSSIBLY NEAR WHITEOUT CONDITIONS
ESPECIALLY NEAR THE LAKESHORE.

INVERSION HEIGHTS FALL TO UNDER 7K FEET WEDNESDAY INTO WEDNESDAY
NIGHT. HOWEVER...VERY STEEP LAPSE RATES WILL EXIST RIGHT THROUGH
WEDNESDAY NIGHT OVER THE UNFROZEN LAKE. LWA BUFKIT OVERVIEWS SHOW
THE STRONGEST LIFT WITHIN THE DGZ THEN. COMMONLY WHEN THIS HAPPENS
THE ACCUMULATING SNOW AND GREATEST IMPACTS STAYS RELATIVELY CLOSE
TO THE LAKESHORE. SO I WILL KEEP KENT AND BARRY COUNTIES OUT OF
THE HEADLINES FOR NOW...BUT THE SITUATION WILL NEED TO BE
MONITORED CLOSELY.

THE FLOW TURNS ON THURSDAY AS THE MOISTURE DEPTH DECREASES. WILL
KEEP THE EXPIRATION TIME AT 10 AM...TO ACCOUNT FOR THE POTENTIAL
FOR LINGERING IMPACTS THROUGH THE MORNING COMMUTE.

.LONG TERM...(FRIDAY THROUGH TUESDAY)
ISSUED AT 253 PM EST TUE FEB 9 2016

WE CONTINUE TO EXPECT THAT LIKELY THE COLDEST AIR OF THE ENTIRE
WINTER WILL OCCUR THIS WEEKEND...ESPECIALLY ON SAT. LAKE EFFECT MAY
BE A PLAYER FOR A BIT ON FRI...BUT WILL LIKELY BECOME A NON-FACTOR
OVER THE WEEKEND.

A REINFORCING SHOT OF ARCTIC AIR THAT WILL BE EVEN COLDER THAN THE
CURRENT ONE WILL BE MOVING INTO THE AREA DURING THE DAY ON FRI. WE
COULD SEE A BRIEF BAND OF SNOW ACCOMPANY THIS FRONT...WITH
ENHANCEMENT OCCURRING NEAR THE LAKE.

THE COLD AIR WILL SETTLE IN FOR SAT...BUT WE ARE NOT EXPECTING MUCH
LAKE EFFECT TO OCCUR HERE. THE SFC PRESSURE PATTERN CONTINUES TO
INDICATE THAT WE WILL SEE A NNE FLOW TAKE SHAPE. THIS WILL SEND MOST
LAKE EFFECT FROM LAKE MICHIGAN OVER THE LAKE AND TO THE WRN SIDE OF
IT. WE WILL LIKELY JUST SEE COLD TEMPS WITH HIGHS ONLY AROUND 10
ABOVE WITH AT LEAST SOME...IF NOT A GOOD DEAL OF SUNSHINE.

THE BREAK IN SNOW SHOWERS WILL LIKELY BE BRIEF AS WE WILL HAVE
ANOTHER CHC MOVING INTO THE AREA BY LATE SUN. THIS WILL COME VIA A
MORE ORGANIZED NRN STREAM SHORT WAVE. THERE WERE SOME INDICATIONS
THAT THERE COULD BE SOME PHASING OF THE TWO STREAMS. THE TREND IS
FOR THE SRN STREAM TO BE SHUNTED FURTHER SOUTH...WHICH LOOKS
REASONABLE GIVEN THE AMPLIFIED FLOW THAT WILL BE IN PLACE. WITHOUT
GULF MOISTURE AVAILABLE...AND WHAT LOOKS TO BE A SSE WIND...THIS
DOES NOT LOOK SIGNIFICANT AT THIS TIME.

WE ARE LOOKING FOR MORE CHCS OF SNOW FOR MON AND TUE OF NEXT WEEK.
THESE CHCS ARE A BIT UNCERTAIN RIGHT NOW THIS FAR OUT WITH A LOT OF
SYSTEMS THAT WILL BE INTERACTING WITH EACH OTHER ACROSS THE COUNTRY.
WE WILL GO WITH LOWER CHCS OF SNOW WITH MODERATING TEMPS FOR THE
TIME BEING WITH LOWER HEIGHTS REMAINING IN PLACE.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1159 PM EST TUE FEB 9 2016

MVFR TO VFR CONDITIONS CAN BE EXPECTED AT MOST OF THE TERMINALS
OVERNIGHT AND WEDNESDAY WITH A FEW LIGHT SNOW SHOWERS. HOWEVER
OCNL IFR VSBYS WILL OCCASIONALLY IMPACT MKG AND AZO DUE TO
HEAVIER LAKE EFFECT SNOW BANDS. WINDS WILL CONTINUE OUT OF THE
NORTH-NORTHWEST AT 15 TO 25 KTS.

&&

.MARINE...
ISSUED AT 253 PM EST TUE FEB 9 2016

THE COMBINATION OF INCREASING MIXING HEIGHTS AND TIGHTENING
PRESSURE GRADIENT SUPPORTS HAZARDOUS CONDITIONS FOR SMALL CRAFT
OUT ON LAKE MICHIGAN FOR THE NEXT FEW PERIODS. FREEZING SPRAY
COULD BE AN ISSUE AS WELL.


&&

.HYDROLOGY...
ISSUED AT 249 PM EST TUE FEB 9 2016

THE MAPLE RIVER AT MAPLE RAPIDS CONTINUES TO SHOW IMPROVEMENT AS
EXPECTED. REALISTICALLY...THE RATE AT WHICH IT IS FALLING MAY
ALLOW IT TO BE DROPPED BY FRIDAY. THE MAIN STORY THEN SHIFTS TO
THE COLDEST AIR OF THE SEASON...POSSIBLY LEADING TO ICE BUILD UP
RIGHT THROUGH THE WEEKEND.

TEMPERATURES WILL GRADUALLY BECOME COOLER EACH DAY THIS WEEK WITH
DAYTIME HIGHS BELOW FREEZING AND OVERNIGHT LOWS FALLING INTO THE
TEENS THROUGH FRIDAY. THE BRUNT OF THE COLD AIR SEEMS TO MAKE IT
IN BY THE WEEKEND WITH LOWS IN THE SINGLE DIGITS FOR MANY
LOCATIONS AND SOME AREAS POSSIBLY DIPPING BELOW ZERO. THIS WILL
CERTAINLY ASSIST IN ICE FORMATION FOR STREAMS AND RIVERS...BECOMING
MORE OF A FOCUS AS THE WEEK PROGRESSES.

PRECIPITATION WILL BE ALL SNOW THROUGH THE PERIOD WITH LITTLE IN
THE WAY OF RUNOFF. THE HEAVIEST SNOWFALL WILL STAY HUGGED ALONG
THE LAKE MICHIGAN BORDERING COUNTIES AND OTHER AREAS TYPICAL OF
NORTHWEST FLOW. THIS WILL JUST BE A DELAYED CONCERN IF ADDITIONAL
LIQUID MOISTURE IS RECEIVED IN THE NEAR FUTURE. AS FOR NOW...THE
TOTALS OVER THE COURSE OF THE WEEK ARE ONLY LOCALLY HIGH NEAR THE
LAKE WITH AREA WIDE AVERAGES STAYING RELATIVELY LOW WHEN
CONSIDERING THE EPISODIC NATURE OF THE EVENT.

&&

.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.

&&

$$

SYNOPSIS...MJS
SHORT TERM...MJS
LONG TERM...NJJ
AVIATION...MEADE
HYDROLOGY...JAM
MARINE...MJS



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