National Weather Service Weather Forecast Office

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FXUS63 KGRR 011647
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1145 AM EST SUN FEB 1 2015

LATEST UPDATE...
AVIATION

.MESOSCALE DISCUSSION...
ISSUED AT 1009 AM EST SUN FEB 1 2015

WIDESPREAD LIGHT TO MODERATE SNOW CONTINUES AS OF THIS WRITING AS
THE FIRST HALF OF A MAJOR WINTER STORM TAKES SHAPE ACROSS SOUTHERN
LOWER MICHIGAN. WE HAVE BEEN ANALYZING BOTH THE 12Z NAM AND 06Z
GFS MULTI-LAYER F-VECTOR CONV FIELDS (FN) AS WELL AS LOCATION OF
CONVECTIVE INSTABILITY...DEFORMATION ZONE...AND ANTICIPATED
MOVEMENT OF THE MID LEVEL DRY SLOT. BOTH MODEL SOLUTIONS ARE
INDICATING OUR SOUTHERN AND SOUTHEASTERN CWA MAY BE IN THE SWEET
SPOT FOR DEEP FGEN AND CONVECTIVE INSTABILITY (-EPV). THE TREND IN
THE DEFORMATION ZONE CONTINUES TO INCH NORTH...WITH AZO TO BTL AND
JXN SQUARELY IN THE DEFORMATION TONIGHT (00Z-06Z) AND PERHAPS
ORIENTING NE TOWARD LAN AS WELL. THIS IS IN COMBINATION WITH WHAT
APPEARS TO BE A DUAL-LAYER DGZ DEVELOPING TONIGHT ALONG WITH DEEP
LIFT CONTINUING IN SATURATED CONDITIONS. 06Z GFS HAS BEEN ABOUT
SPOT ON WITH SNOW TOTALS SO FAR AT LEAST FOR LOCATIONS NEAR AND
SOUTH OF I-96. WIDESPREAD 3"-5" HAS OCCURRED IN THIS REGION AND
THE WORST IS YET TO COME. I BELIEVE THE HEIGHT OF THE STORM WILL
BE 21Z-06Z AS THE DEFORMATION ZONE MOVES IN AND WINDS CONTINUE
PICKING UP. IT IS CONCEIVABLE THAT THE HARDEST HIT LOCATIONS WILL
PICK UP AN ADDITIONAL 10" OR MORE OF SNOW THROUGH TONIGHT.


&&

.SYNOPSIS...
ISSUED AT 326 AM EST SUN FEB 1 2015

A STRENGTHENING WINTER STORM WILL DUMP QUITE A BIT OF SNOW ON
SOUTHWEST LOWER MICHIGAN TODAY INTO TONIGHT. IN ADDITION...WINDS
WILL INCREASE AND CREATE NEAR BLIZZARD CONDITIONS AT TIMES FROM 1 PM
THROUGH 1 AM. THE HEAVIEST SNOW WILL FALL ALONG/SOUTH OF I-94 WHERE
OVER A FOOT OF SNOW IS EXPECTED. SNOW ACCUMULATIONS WILL TAPER OFF
THE FARTHER NORTH YOU GO BUT EVEN IN GRAND RAPIDS AND LANSING
SNOWFALL TOTALS WILL BE CLOSE TO 10 INCHES. REALIZE THOUGH THAT
THESE TOTALS WILL BE SPREAD OUT OVER 24 HOURS. SIGNIFICANT IMPACTS
ARE EXPECTED FROM THIS AFTERNOON THROUGH TONIGHT SO THOSE PLANNING
TO TRAVEL SHOULD ALLOW PLENTY OF TIME TO REACH THEIR DESTINATION.

HIGHS WILL REMAIN BELOW FREEZING THIS WEEK WITH TEMPERATURES IN THE
TEENS MONDAY AND THURSDAY.

&&

.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 326 AM EST SUN FEB 1 2015

FORECAST CONCERNS DEAL WITH THE DEVELOPING WINTER STORM.

WE MADE A FEW CHANGES TO THE GOING HEADLINES. BASICALLY WE NUDGED
THE HEADLINES NORTH A ROW OF COUNTIES AND NOW INCLUDE GRAND RAPIDS
IN THE WINTER STORM WARNING.

THERE IS A LOT GOING FOR THIS STORM. FIRST IT/S A SLOW MOVING LOW
THAT IS STRENGTHENING AS IT MOVES ACROSS THE NORTHERN OHIO VALLEY.
SECOND...THERE IS A 60KT LLJ AHEAD OF THE LOW THAT BRINGS IN
ABUNDANT MOISTURE FROM THE GULF. THIRD...THE TROWAL NOW WORKS INTO
FAR SOUTHERN LOWER MICHIGAN PLACING A SWEET SPOT FOR HEAVY SNOW
ACROSS THE SOUTHERN CWA. FOURTH...THE DGZ...WHILE FAIRLY HIGH UP
INITIALLY...IS RATHER LARGE AND MORE IMPORTANTLY NEARLY ISOTHERMAL.
THAT/S SHOWN TO BE CONDUCIVE FOR SNOWFALL PRODUCTION. QPF OF 2/3 TO
3/4 OF AN INCH COUPLED WITH MIXING RATIOS NEAR 18:1 WOULD YIELD
SNOWFALL ACCUMULATIONS NORTH OF A FOOT OVER THE SOUTHERN CWA AND
CLOSE TO 10 INCHES ALONG I-96. EVEN THOUGH THIS IS A LONG DURATION
EVENT...AT LEAST 30 HOURS...WE FELT THIS JUSTIFIED ADDING ANOTHER
ROW OF COUNTIES TO THE WARNING. ADDITIONALLY...TRAVEL THIS EVENING
MAY BE GREATER THAN NORMAL DUE TO SUPER BOWL RELATED EVENTS.
ALSO...THE SLOWER NATURE OF THIS SYSTEM MEANS IT WILL LIKELY DRAG ON
INTO MONDAY MORNING AND AFFECT THE MONDAY MORNING COMMUTE.

COMPOUNDING THE SNOW WILL BE THE DEVELOPMENT OF STRONG WINDS THIS
AFTERNOON. BUFKIT WIND PROFILES SUGGEST WE/LL TAP INTO 35 KNOT WINDS
AS THE COLDER AIR WORKS INTO THE SYSTEM. THIS SHOULD RESULT IN
CONSIDERABLE BLOWING AND DRIFTING...AND MAYBE NEAR BLIZZARD
CONDITIONS AT TIMES. THE WINDS WILL DIE DOWN AFTER MIDNIGHT TONIGHT
BUT CLEANUP OF THE STORM WILL LAST WELL INTO MONDAY.

SNOW WILL DIMINISH MONDAY MORNING BUT MORE LIGHT SNOW IS POSSIBLE
TUESDAY AS A TROUGH MOVES THROUGH LOWER MICHIGAN.

.LONG TERM...(TUESDAY NIGHT THROUGH SATURDAY)
ISSUED AT 326 AM EST SUN FEB 1 2015

THE ARCTIC COLD FRONT WITH THE LONG ADVERTISED UPPER LEVEL PV
ANOMALY PUSH THROUGH THE AREA WEDNESDAY...WITH CHANCES FOR SNOW
WINDING DOWN WEDNESDAY EVENING. ESTIMATED SNOW TOTALS ENDING
WEDNESDAY EVENING THAT INCLUDE TUESDAY ARE STILL LOOKING AROUND 1-3
INCHES WITH LOCALLY HIGHER LAKESHORE AMOUNTS...SO LITTLE IMPACT
EXPECTED WITH THIS ROUND OF SNOW.

WIDESPREAD LOWS BELOW ZERO THURSDAY MORNING SEEM QUITE POSSIBLE
GIVEN LIGHT WINDS...A DRY AIRMASS...AND LIKELY SNOWPACK. MINIMAL
LAKE EFFECT SNOW SHOWER CONCERNS THURSDAY/FRIDAY WITH VERY DRY AND
COLD AIR IN PLACE. FAVORED ECMWF SHOWS THE NEXT COLD FRONT WITH
RESPECTABLE ATTENDANT MOISTURE PUSHING INTO THE AREA SATURDAY...SO
PROSPECTS FOR SNOW NEXT WEEKEND ARE INCREASING.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY)
ISSUED AT 1145 AM EST SUN FEB 1 2015

A SNOWSTORM WILL CONTINUE IN PROGRESS THIS AFTERNOON THROUGH THIS
EVENING RESULTING IN WIDESPREAD LIFR CONDITIONS THROUGH LATE THIS
EVENING DUE TO MODERATE TO HEAVY SNOW AND BLOWING SNOW. NORTHEAST
WINDS WILL CONTINUE TO INCREASE TO 15 TO 25 KTS WITH FREQUENT GUSTS
TO AROUND 30 KTS LATE THIS AFTERNOON AND EVENING WHICH WILL FURTHER
REDUCE VISIBILITIES IN BLOWING SNOW. LIGHT RIME ICING WILL BE
POSSIBLE GENERALLY BELOW 2000 FT AGL.

CONDITIONS WILL GRADUALLY IMPROVE TO IFR THEN MVFR DURING THE EARLY
MORNING HOURS MONDAY AS THE SNOW MOVES OUT AND CIGS BEGIN TO
IMPROVE. NORTH WINDS WILL REMAIN BRISK AT 15 TO 25 KTS OVERNIGHT.
CONDITIONS WILL GRADUALLY IMPROVE TO VFR MID TO LATE MONDAY MORNING
WHEN WIND SPEEDS WILL DIMINISH A LITTLE BIT OUT OF THE NNW AT 15 TO
20 KTS. CONDITIONS SHOULD THEN REMAIN VFR THROUGH 18Z MON.

&&

.HYDROLOGY...
ISSUED AT 326 AM EST SUN FEB 1 2015

WE`RE LIKELY TO SEE ICE FORMATION THIS WEEK WITH BELOW FREEZING
TEMPERATURES EXPECTED THROUGHOUT THE WEEK. RIVER LEVEL FLUCTUATIONS
MAY DEVELOP AS A RESULT OF ICE BUILDUP.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...WINTER STORM WARNING UNTIL 6 AM EST MONDAY FOR MIZ056>059-
     064>067-071>074.

     WINTER WEATHER ADVISORY UNTIL 6 AM EST MONDAY FOR MIZ037>040-
     043>046-050>052.

LM...NONE.
&&

$$

MESOSCALE...HOVING
SYNOPSIS...04
SHORT TERM...04
LONG TERM...TJT
AVIATION...LAURENS
HYDROLOGY...04