FXUS63 KGRR 102056
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
400 PM EST THU DEC 10 2009
LATEST UPDATE...ALL BUT AVIATION...
.SYNOPSIS...(400 PM EST THU DEC 10 2009)
THE WINTER STORM WILL CONTINUE TO IMPACT THE AREA TONIGHT.
SNOW...WIND AND BLOWING SNOW WILL OCCASIONALLY PRODUCE BLIZZARD
CONDITIONS WITH VISIBILITIES FALLING TO NEAR ZERO. TRAVEL IN THIS
AREA WILL BE MAJORLY IMPACTED INTO TONIGHT.
ELSEWHERE OVER SOUTHWEST LOWER MICHIGAN...THE SNOW SHOWERS WILL BE
LESS INTENSE AND LESS FREQUENT. HOWEVER...THE BRISK WINDS WILL
CAUSE BLOWING AND DRIFTING SNOW. THEREFORE...A WINTER WEATHER
ADVISORY IS IN EFFECT THROUGH TONIGHT.
CONDITIONS ARE EXPECTED TO IMPROVE FRIDAY AS THE SNOW AND WIND
DIMINISH.
&&
.SHORT TERM...(400 PM EST THU DEC 10 2009)
(THIS AFTERNOON THROUGH SATURDAY)
HAVE CONTINUED THE CURRENT HEADLINES THROUGH TONIGHT. I DID FEATURE
A LULL IN THE STORM FOR THE AFTERNOON COMMUTE. THIS COINCIDES WITH A
THERMAL RIDGE AROUND 700 MPH. WE LOSE THE SATURATION AROUND -20 DEG
C FROM ABOUT 21Z TO 00Z.
HOWEVER CONDITIONS CHANGE BY 00Z AS THE NEXT UPSTREAM WAVE ARRIVES.
THIS WILL CAUSE THE SNOW SHOWERS TO STRENGTHEN THIS EVENING.
MOISTURE DEEPENS AND THEN REMAINS RELATIVELY DEEP THROUGH THE
NIGHT...UP TO AROUND -25 DEG C ACROSS THE WARNING AREA. PERSISTENT
SURFACE CONVERGENCE IS SHOWN IN A BAND BETWEEN GRR AND AZO
OVERNIGHT. SEVERAL MODELS SHOW THIS SCENARIO. OVERVIEWS FROM
BUFKIT ESPECIALLY AROUND LWA SHOW STRONGER LIFT WITHIN THE DGZ FROM
00Z TO 06Z. THIS SUPPORTS HEAVY SNOW. THE -10 DEG C ISOTHERM RISES
OVERNIGHT. WE STILL TAP INTO THE 30 TO 40 KNOT WINDS THROUGH THE
NIGHT...THUS WILL MAINTAIN THE BLIZZARD WARNING.
FURTHER EAST FOR THE ADVISORY AREA...SURFACE CONVERGENCE EXTENDS TO
AT LEAST LAN THROUGH THE NIGHT. THIS SUPPORTS LAKE EFFECT SNOW
BANDS EXTENDING WELL INLAND. WHILE THE BANDS WILL LIFT NORTH OF JXN
FOR A WHILE...WIND CHILL VALUES WILL REMAIN CLOSE TO ADVISORY
LEVELS. THUS WILL INCORPORATE THIS INTO THE WINTER WEATHER ADVISORY.
&&
.LONG TERM...(400 PM EST THU DEC 10 2009)
(FRIDAY THROUGH THURSDAY)
ONCE THE WINDS AND LAKE EFFECT SNOW WIND DOWN ON FRIDAY...LOOKS LIKE
NO
BIG STORMS IN THE EXTENDED. ONE DECENT COLD SHOT IS EXPECTED FOR
TUESDAY TO THURSDAY NEXT WEEK...OTHERWISE TEMPS WILL NOT BE
DEVIATING TOO FAR FROM NORMAL.
INVERSION HEIGHTS LOWER ON FRIDAY AS HEIGHTS RISE A BIT AND SFC
RIDGING BEGINS TO BUILD IN. THE TREND WILL BE FOR WINDS AND LES
DECREASING THROUGH THE DAY WITH ONLY LIGHT ACCUMS ON THE ORDER OF AN
INCH OR TWO WEST OF US-131. THEN THE LES SHOULD SHUT OFF LATER
FRIDAY NIGHT AS FLOW BECOMES SOUTH AS SFC RIDGE AXIS MOVES EAST.
WEAK SHORTWAVE TROUGH APPROACHES SUNDAY WITH ATMOSPHERE MOISTENING
UP AND WAA/ISENTROPIC LIFT HELPING SOME LIGHT SNOW TO BREAK OUT LATE
SATURDAY NIGHT. COULD BE A MIX ACROSS THE SOUTH IF THE LOW LEVEL WAA
IS STRONG ENOUGH...BUT LEFT P TYPE AS ALL SNOW FOR NOW. THIS TROUGH
KICKS EAST SUNDAY NIGHT WITH SHORTWAVE RIDGING BRIEFLY REPLACING IT.
AMPLIFYING LONGWAVE TROUGH ACROSS WESTERN CENTRAL CONUS WILL
GENERATE SFC CYCLONE THAT MOVES ACROSS UPPER GREAT LAKES ON MONDAY.
SOUTHWEST FLOW AHEAD OF THE LOW WILL MODERATE TEMPS ENOUGH FOR SOME
MIX WITH RAIN IN LIGHT PRECIP OUT AHEAD OF THE ARCTIC FRONT. THEN
COLD WITH LAKE EFFECT SNOW SHOWERS FOR TUESDAY THROUGH THURSDAY.
&&
.AVIATION...(100 PM EST THU DEC 10 2009)
LAKE EFFECT SNOWSHOWER ACTIVITY WITH TOPS TO 10KFT AND ASSOCIATED
SFC WIND GUSTS GREATER THAN 30KTS WILL CONTINUE WITH LIFR-IFR
CONDITIONS WEST OF RT-127 THROUGH THIS EVENING. A GRADUAL
IMPROVEMENT TO MVFR-VFR EXPECTED WED AS HIGH PRESSURE ALONG WITH
WARMER AND DRIER AIR BEGIN TO STABILIZE THE LOW LEVEL CONVECTIVE
INSTABILITY OVER THE LAKE.
ORIENTATION OF SNOW SHOWER BANDING...AS SEEN ON RADAR...WILL REMAIN
FAIRLY STEADY WITH A TRANSITION TO A MORE WEST TO EAST ORIENTATION
OVERNIGHT. THIS WILL LIKELY BRING SLIGHTLY STEADIER SNOW INTO
KAZO...KBTL AND POSSIBLY KJXN BEFORE THE BANDS BEGIN TO DISSIPATE
WED MORNING.
&&
.MARINE...(400 PM EST THU DEC 10 2009)
THE GALE WARNING WILL BE EXTENDED INTO TONIGHT. THEREAFTER IT
APPEARS WINDS WILL GRADUALLY DIMINISH INTO FRIDAY AND FRIDAY NIGHT
AS A RIDGE OF HIGH PRESSURE BUILDS TO OUR SOUTH.
&&
.HYDROLOGY...(400 PM EST THU DEC 10 2009)
NO HYDRO ISSUES EXPECTED AS COLD AIR HAS FROZEN ANY STANDING WATER.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...BLIZZARD WARNING MUSKEGON...KENT...OTTAWA...ALLEGAN...BARRY...
VAN BUREN AND KALAMAZOO COUNTIES THROUGH TONIGHT.
WINTER WEATHER ADVISORY FOR THE REST OF THE CWA THROUGH TONIGHT.
LM...GALE WARNING ST. JOSEPH TO MANISTEE THROUGH TONIGHT.
&&
$$
SYNOPSIS: MJS
SHORT TERM: MJS
LONG TERM: EJO
AVIATION: DKC
MARINE: MJS
HYDROLOGY: MJS
