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000
FXUS63 KGRR 021627
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1130 AM EST MON MAR 2 2015

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 328 AM EST MON MAR 2 2015

PARTLY TO MOSTLY SUNNY SKIES WILL COVER THE GREAT LAKES TODAY BEFORE
LOW PRESSURE SPREADS A MIX OF SNOW SLEET FREEZING RAIN AND RAIN INTO
LOWER MICHIGAN TUESDAY. SEVERAL INCHES OF SNOW ARE POSSIBLE NORTH OF
I-96 TUESDAY AND UP TO A TENTH OF AN INCH OF ICE SOUTH OF I-96.
ANOTHER BLAST OF ARCTIC AIR WILL FLOW OVER THE STATE THURSDAY WHEN
HIGHS ONLY REACH THE TEENS. WARMER WEATHER IS EXPECTED BY THE
WEEKEND.

&&

.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 328 AM EST MON MAR 2 2015

LITTLE CHANGE TO THE GOING FORECAST. CONCERNS DEAL WITH THE
APPROACHING LOW PRESSURE SYSTEM TUESDAY.

LOW PRESSURE EMERGING FROM THE CENTRAL ROCKIES WILL MAKE A BEELINE
TOWARD THE GREAT LAKES TONIGHT AND TUESDAY ON THE HEELS OF A 180KT
UPPER JET THAT PASSES OVER THE CENTRAL CWA. FOR SEVERAL DAYS SHORT
RANGE MODELS HAVE BEEN SHOWING THIS LOW PHASING WITH A LOW MOVING
ACROSS SOUTHERN CANADA. THIS PHASING CREATES A POTENT SYSTEM AND
WE/LL SEE AROUND A HALF INCH QPF FROM IT. STRONG ISENTROPIC LIFT ON
THE 290K SFC QUICKLY SATURATES THAT COLUMN AFTER 06Z TONIGHT AND WE
SHOULD SEE SNOW DEVELOP BY 4-5 AM. INITIALLY FORECAST SOUNDINGS ARE
COLD ENOUGH TO SUPPORT ALL SNOW FOR THE CWA WHICH WILL ACTUALLY BE
GOOD NEWS IN THE SOUTHERN CWA WHERE WE/LL SEE SOME FREEZING RAIN
DEVELOP LATER IN THE DAY. TO HAVE SOME SNOW TO ABSORB THE RAIN AND
PROVIDE SOME GRIT ON THE ROADS MAY BE A GOOD THING AS THE COLUMN
WARMS AROUND 800 MB AND THE SNOW TURNS TO RAIN. LOOKING AT SOUNDINGS
FROM THE ECMWF/GFS/NAM...THEY GENERALLY SUPPORT MOSTLY SNOW NORTH OF
M-46. IN THIS AREA 3-5 INCHES SEEMS POSSIBLE TUESDAY. SOUTH OF THERE
IT/S LOOKING LIKE A 1-3 INCH SNOWFALL WITH UP TO A TENTH OF AN INCH
OF FREEZING RAIN. SOME SLEET IS ALSO POSSIBLE DURING THE TRANSITION
PERIODS. THE MAIN SURGE OF WARMER AIR ACTUALLY COMES IN AROUND 21Z
THROUGH 01Z OR SO AND WE COULD SEE SOME RAIN SOUTH OF I-94. GIVEN
THE COLD GROUND TEMPERATURES...SECONDARY ROADS MAY REMAIN COLD
ENOUGH DESPITE TEMPERATURES RISING ABOVE FREEZING SOUTH OF I-96 TO
SEE MOSTLY FREEZING RAIN. THUS ICY CONDITIONS WILL BE MORE PREVALENT
ON DIRT/GRAVEL ROADS...ALTHOUGH HAVING SOME SNOW ON THE GROUND WILL
PROBABLY HELP.

THE TRAILING COLD FRONT MOVES THROUGH AROUND 00Z AND WE/LL SEE A
TRANSITION BACK TO LIGHT SNOW TUESDAY EVENING. BREEZY CONDITIONS
WILL DEVELOP TUESDAY EVENING AS HIGH PRESSURE QUICKLY BUILDS IN AND
THE GRADIENT TIGHTENS. SNOW SHOWERS ARE POSSIBLE WEDNESDAY AS H8
TEMPS FALL TO -24C...BUT GIVEN THE LIMITED MOISTURE BEHIND THE FRONT
WE ARE NOT EXPECTED MUCH IN THE WAY OF ACCUMS.

.LONG TERM...(WEDNESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 328 AM EST MON MAR 2 2015

AFTER ANOTHER SHOT OF BITTER COLD AIR FOR THE MID WEEK PERIOD WITH
TEMPERATURES 25 DEGREES BELOW NORMAL... IT LOOKS LIKE WE MAY FINALLY
SEE TEMPERATURES ABOVE FREEZING NEXT WEEKEND.

LAKE EFFECT SNOW SHOWERS ARE EXPECTED WEDNESDAY NIGHT AND THURSDAY
AS OUR NEXT INSTALLMENT OF ARCTIC AIR WITH H8 TEMPS AROUND -22C
SLIDES ACROSS A STILL OPEN LAKE MICHIGAN. THE UPPER TROUGH AND CORE
OF THE COLDEST H8 AIR ARE SHOWN TO IMPACT THE AREA DURING THIS TIME
SO WILL CARRY LIKELY POPS WEST OF HIGHWAY 131 WITH A FEW INCHES OF
ACCUMULATION POSSIBLE.

MOISTURE LOOKS SHALLOW BUT THE DGZ SHOULD BE IN CLOUD LAYER. THE
BEST CHANCE FOR ACCUMULATIONS ALONG THE LAKESHORE WOULD BE LATER
WEDNESDAY NIGHT INTO EARLY THURSDAY MORNING WHEN SFC CONVERGENCE IS
MAXIMIZED.

MODERATING TEMPERATURES ARE EXPECTED FRIDAY AND SATURDAY AS THE NRN
STREAM RETREATS AND THE UPR FLOW GOES MORE ZONAL. ITS QUESTIONABLE
HOW WARM WE GET GIVEN THE EXPANSIVE SNOW COVER AND UNCERTAINTY IN
AMOUNT OF CLOUD COVER... BUT TEMPS ABOVE FREEZING ARE CERTAINLY
POSSIBLE ON SATURDAY. THE GFS IS DRIVING ANOTHER COLD FRONT THROUGH
ON SATURDAY NIGHT WHICH WOULD HALT THE WEEKEND WARM UP BUT THE ECMWF
DOES NOT SHOW THIS FRONT.

LOOKING EVEN FARTHER AHEAD.... BOTH THE ECMWF AND GFS SHOW THE
POSSIBILITY OF ONE MORE ARCTIC SURGE ON MON-TUE MARCH 9-10. IT IS
BEHIND THIS THAT THE PATTERN CHANGE TOWARD WARMER TEMPERATURES MAY
FINALLY ENSUE BY LATER THAT WEEK.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY)
ISSUED AT 1130 AM EST MON MAR 2 2015

MVFR/VFR CONDITIONS WILL CONTINUE THIS AFTERNOON AND EVENING AND FOR
MOST OF THE OVERNIGHT PERIOD. CONDITIONS WILL DETERIORATE RAPIDLY TO
IFR/LIFR DURING THE MID MORNING HOURS TUESDAY AS SNOW DEVELOPS.

SNOW WILL BECOME MIXED WITH AND/OR CHANGE OVER TO SLEET AND LIGHT
FREEZING RAIN TOWARD MIDDAY SO A LIGHT ICING THREAT WILL EXIST AS
WELL.

LIFR/IFR CONDITIONS WILL THEN CONTINUE THROUGH 18Z DUE TO LOW CIGS
AND MIXED PCPN. IT WILL ALSO BECOME WINDY BY MID TO LATE MORNING A
SE WINDS RAMP UP TO 15 TO 20 KTS WITH GUSTS TO NEAR 25 KTS.

&&

.HYDROLOGY...
ISSUED AT 1140 AM EST SUN MAR 1 2015

THE FORECAST GETS A LITTLE TRICKY IN THE UPCOMING WEEK WITH THE
APPROACHING SYSTEM GOING INTO TUESDAY. TEMPERATURES COULD VARY
QUITE A BIT RIGHT ALONG WITH EXPECTED PRECIPITATION TOTALS AND
PRECIPITATION TYPE. THE CURRENT GUIDANCE SUGGESTS WE COULD GET A
BIT FURTHER INTO MILDER AIR (NEAR NORMAL) AND ADD MORE LIQUID
PRECIPITATION AS OPPOSED TO SNOW. OVERALL....IT IS NOT A DRASTIC
WARM UP AND AMOUNTS MAY REMAIN AROUND OR BELOW HALF AN INCH. THIS
COULD MOSTLY BE SOAKED UP BY CURRENT SNOW PACK. WITH LOW RIVER
LEVELS AND GIVEN SITUATION...THIS SHOULD NOT RAISE ANY IMMEDIATE
CONCERN BUT WILL BE ADDED LIQUID TO BE CONSIDERED IN FORECASTS
DOWN THE ROAD.

THE GOOD NEWS IS THAT THE SYSTEM LAST NIGHT INTO TODAY WAS QUITE
LACKLUSTER IN REGARDS TO TOTALS. THEREFORE...WHAT WE MISSED LAST
NIGHT WILL JUST SUBTRACT FROM THE OVERALL WEEKLY AMOUNTS WE WERE
LOOKING AT YESTERDAY. THOUGH IT WAS NOT ANYTHING TOO HEAVY TO
BEGIN WITH IT JUST RAISES CONFIDENCE THAT ANY UPWARD TRENDS IN
TEMPERATURES WILL NOT HAVE AS MUCH OF A NEGATIVE IMPACT.
CONDITIONS ARE EXPECTED TO REMAIN STABLE FOR NOW AND IN THE NEAR
TERM.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&

$$

SYNOPSIS...04
SHORT TERM...04
LONG TERM...MEADE
AVIATION...LAURENS
HYDROLOGY...JAM