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000
FXUS63 KGRR 011640
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1140 AM EST SUN MAR 1 2015

LATEST UPDATE...
HYDRO

.SYNOPSIS...
ISSUED AT 328 AM EST SUN MAR 1 2015

LIGHT SNOW WILL CONTINUE TO WIND DOWN TODAY AS A WAVE OF LOW
PRESSURE MOVES EAST. ANOTHER STORM WILL HEAD TOWARD LOWER MICHIGAN
AND BRING A MIX OF SNOW SLEET FREEZING RAIN AND PERHAPS RAIN
TUESDAY...BUT SHOULD BE DONE BY LATE TUESDAY. ANOTHER SHOT OF ARCTIC
AIR WILL FOLLOW AND HIGHS WILL REMAIN IN THE TEENS THURSDAY BUT WILL
WARM INTO THE MID 30S BY NEXT WEEKEND.

&&

.UPDATE...
ISSUED AT 934 AM EST SUN MAR 1 2015

I UPDATED THE GRIDS AND FORECAST TO BETTER DEPICT THE CURRENT SNOW
SHOWERS FROM GRR TO THE LAKE SHORE. THESE ARE NOT SHOWN BY ANY OF
THE MODELS BUT USING THE 1000/950 OMEGA AND CONVERGENCE FIELDS FROM
THE RAP AND NAM IT CAN BE SEEN WHY THESE SHOWERS ARE HAPPENING.
THE CONVERGENCE CAUSING THESE SNOW SHOWERS GOES AWAY BY NOON SO BY
THEN THE SNOW SHOWERS NEAR GRR TO THE LAKE SHORE SHOULD COME TO AN
END. ACCUMULATIONS WILL MOSTLY BE UNDER A HALF INCH. OTHERWISE THE
REST OF THE FORECAST REMAINS UNCHANGED.

&&

.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 328 AM EST SUN MAR 1 2015

FORECAST CONCERNS THIS MORNING DEAL WITH THE ONGOING LIGHT SNOW AND
THE MIXED PCPN EVENT TUESDAY. TWEAKED PCPN TYPE GRIDS TUESDAY AND
POPS TODAY...OTHERWISE MUCH OF THE FORECAST WAS UNCHANGED.

REGIONAL RADAR SHOWS LIGHT SNOW BEGINNING TO WIND DOWN ACROSS LOWER
MICHIGAN. THE SYNOPTIC SNOW SOUTH M-46 WILL LIKELY DIMINISH BEFORE
THE SW LAKE EFFECT SNOW ONGOING NORTH OF MKG...BUT EVEN THAT WILL
DIMINISH LATE THIS MORNING OR EARLY THIS AFTERNOON. ANY ACCUMS WILL
BE A HALF INCH OR LESS.

THE NEXT SYSTEM WILL ARRIVE EARLY TUESDAY...PERHAPS LATE MONDAY
NIGHT...AND BRING A MIX OF FREEZING RAIN/SLEET/SNOW/RAIN. THIS
SYSTEM IS A FAIRLY DYNAMICAL ONE AND PROGD TO PUSH A 70KT LLJ ACROSS
OHIO TUESDAY AND DRAWING ABUNDANT MOISTURE NORTHWARD. ISENTROPIC
LIFT IS VERY IMPRESSIVE ON THE 290K SFC WITH 40-50KTS PERPENDICULAR
TO THE PRESSURE SFCS. THIS WILL RESULT IN RAPID SATURATION EARLY
TUESDAY AND QUICK PCPN DEVELOPMENT. GIVEN THE COLD AIR IN PLACE ALL
OF THE PCPN WILL BEGIN AS SNOW. HOWEVER AS THE MID LEVELS
WARM...WE/LL SEE A CHANGE OVER TO FREEZING RAIN AND SLEET. MUCH OF
THE FREEZING RAIN WILL OCCUR SOUTH OF I-94. BASICALLY NORTH OF M-46
ALL OF THE PCPN WILL REMAIN AS SNOW. THE ECMWF AND GFS THERMAL
PROFILES WERE THE MOST SIMILAR WITH THE NAM SHOWING A BIT MORE
PRONOUNCED WARMING AT H85 LATE TUESDAY MORNING. IF THE NAM IS
CORRECT WE COULD SEE A BIT MORE FREEZING RAIN CREEP UP TOWARD I-96.
THE DRY SLOT QUICKLY WORKS IN FROM THE SOUTHWEST TUESDAY MID
AFTERNOON SO PCPN WILL EITHER END QUICKLY OR TURN TO
DRIZZLE/FREEZING DRIZZLE.

OVERALL...SNOW POTENTIAL LOOKS TO BE NEAR 3-4 INCHES FROM I-96
NORTHWARD WITH AN INCH OR TWO SOUTH OF THAT. ICE POTENTIAL LOOKS
LESS THAN A TENTH...BUT STILL ENOUGH TO CAUSE SOME TRAVEL ISSUES.
WHERE 2M TEMPERATURES DO WARM ABOVE FREEZING OVER THE SRN
CWA...SECONDARY ROADS THAT ARE STILL VERY COLD WILL REMAIN BELOW
FREEZING AND EXACERBATE THE FREEZING RAIN POTENTIAL.

.LONG TERM...(TUESDAY NIGHT THROUGH SATURDAY)
ISSUED AT 328 AM EST SUN MAR 1 2015

ANY LINGERING PRECIPITATION TUESDAY NIGHT SHOULD BE VERY LIGHT AS
THE SYSTEM RACES AWAY QUICKLY TO THE NORTHEAST AND THE DEEP MOISTURE
DEPARTS. BREEZY WEST WINDS WILL SEND IN COLDER AIR WITH TEMPERATURES
FALLING INTO THE TEENS/LOWER 20S BY EARLY WEDNESDAY MORNING.

YET ANOTHER ROUND OF BITTER COLD ARCTIC AIR IS IN STORE FOR
WEDNESDAY AND THURSDAY AS H8 AIR AROUND -24C VISITS THE STATE.
SCATTERED LAKE EFFECT SNOW SHOWERS ARE A GOOD BET... PARTICULARLY ON
WEDNESDAY BEFORE SURFACE RIDGING BUILDS IN. TYPICALLY AS WE MOVE
INTO MARCH THE CHARACTER OF LAKE EFFECT IN THE DAYLIGHT HOURS IS
OPEN CELLULAR COVERING MUCH OF THE AREA RATHER THAN FOCUSED JUST
ALONG THE LAKESHORE. WOULD THEREFORE NOT EXPECT ANY SIGNIFICANT SNOW
ACCUMULATIONS ALTHOUGH SOME BRIEFLY INTENSE SNOW SHOWERS ARE
POSSIBLE ACROSS THE ENTIRE AREA.

ARCTIC AIR MASS/NRN STREAM LIFTS OUT LATE IN THE WEEK. A FLATTER
FLOW ALOFT AND SOUTHWEST LOW LEVEL FLOW LEADS TO MODERATING
TEMPERATURES FOR FRIDAY AND SATURDAY HOWEVER STILL A BIT BELOW
NORMAL. THE NORMAL HIGHS FOR NEXT WEEKEND ARE AROUND 40.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY)
ISSUED AT 1125 AM EST SUN MAR 1 2015

FAIRLY EXTENSIVE LOW CLOUD COVER WILL RESULT IN PRIMARILY MVFR
CONDITIONS THIS AFTERNOON. SOME LIGHT SNOW SHOWERS WILL LINGER AT
KMKG INTO THE AFTERNOON BEFORE GRADUALLY DISSIPATING.

CONDITIONS WILL GRADUALLY IMPROVE TO VFR AT ALL THE TERMINALS
TONIGHT AS WINDS SHIFT TO THE WEST/NORTHWEST BEHIND A WEAK SFC
TROUGH. DRIER AIR WILL MOVE IN OVERNIGHT AND ALLOW CIGS TO IMPROVE
TO VFR. THE VFR CONDITIONS WILL THEN CONTINUE THROUGH 18Z MONDAY
WITH WNW WINDS AOB 10 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.
&&

$$

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