000
FXUS63 KGRR 110411
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1211 AM EDT TUE MAR 11 2014

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 306 PM EDT MON MAR 10 2014

A LOW PRESSURE SYSTEM WILL STRENGTHEN AS IT TRACKS UP THE OHIO
VALLEY TUESDAY NIGHT INTO WEDNESDAY. THIS SYSTEM WILL SPREAD A
BAND OF SNOW INTO SOUTHERN LOWER MICHIGAN...WHICH COULD LEAD TO
SOME HAZARDOUS TRAVEL. A MUCH COLDER AIRMASS WILL FILTER IN BEHIND
THIS SYSTEM FOR WEDNESDAY INTO THURSDAY.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT)
ISSUED AT 306 PM EDT MON MAR 10 2014

THE MAIN CHALLENGE IN THE SHORT TERM DEALS WITH THE POTENTIAL FOR
ACCUMULATING SNOW ACROSS SOUTHERN LOWER MICHIGAN TUESDAY NIGHT
INTO WEDNESDAY. OVERALL THE SYSTEM HAS BEEN TRENDING FURTHER NORTH
WHICH RAISES THE RISK FOR GREATER IMPACTS.

AS IT LOOKS RIGHT NOW THE REGION SOUTH OF A SOUTH HAVEN TO MASON
LINE SHOULD SEE THE MOST SNOW WITH THIS STORM. TEMPERATURES WILL
INITIALLY BE TOO WARM FOR IMPACTS 8 PM TUE NIGHT WHEN R/S MIX
LOOKS POSSIBLE...BUT AROUND MIDNIGHT VALUES WILL BE FALLING BELOW
FREEZING. THIS IS WHEN THE HEAVIER SNOW ASSOCIATED WITH STRONGER
MID LEVEL FGEN...WEAKNESS IN THE STABILITY AND DIVERGENCE ALOFT
WILL TRY TO COME TOGETHER LEADING TO THIS POTENTIAL BAND. THE
TIMING OF THE SNOW SHOULD LEAD TO CONSIDERABLE IMPACTS FOR
INTERSTATE 94 FOR THE WED AM COMMUTE. BASED ON THIS WILL GO WITH A
WINTER STORM WATCH FOR MY SOUTHERN COUNTIES. AS FOR 18Z WED...THE
STORM WILL BE PULLING AWAY...SO THE SNOW SHOULD DIMINISH RAPIDLY
FROM WEST TO EAST. SOME IMPACTS COULD CONTINUE WITH TEMPERATURES
WELL BELOW FREEZING.

.LONG TERM...(THURSDAY THROUGH MONDAY)
ISSUED AT 306 PM EDT MON MAR 10 2014

THE MID WEEK COLD BLAST WILL BE BRIEF WITH SOLID WARM ADVECTION
KICKING IN BY THURSDAY NIGHT AS HIGH PRESSURE MOVES TO OUR EAST AND
SOUTHERLY FLOW DEVELOPS.  AFTER HIGHS IN THE LOW TO MID 20S THU...WE
SHOULD SEE MAINLY LOW 40S BY FRIDAY.

A CLIPPER SYSTEM MOVES ACROSS THE SUPERIOR REGION FRIDAY NIGHT.
THIS MAY GIVE THE AREA A LIGHT RAIN CHANGING TO SNOW EVENT.  BEST
CHANCES OF SEEING PCPN SHOULD BE ACROSS THE NW CWA.  ANOTHER SURGE
OF COLD AIR FOLLOWS THIS SYSTEM FOR THE WEEKEND AND IT LOOKS TO
LINGER LONGER OVER THE REGION...AT LEAST THROUGH MONDAY.

THERE IS A WIDE SPREAD IN THE SOLUTIONS FOR ANOTHER SOUTHERN STREAM
SYSTEM BY SUNDAY.  THE EURO HAS A MUCH MORE ORGANIZED SYSTEM...WHILE
THE GFS ONLY DEVELOPS A WEAK LOW.  EITHER WAY IT APPEARS WE WILL BE
ON THE NORTHERN FRINGES OF THE SYSTEM...WITH SOME LIGHT SNOW
POSSIBLE OVER THE FAR SOUTHERN CWA.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1210 AM EDT TUE MAR 11 2014

LIGHT MVFR FOG IS EXPECTED TO FORM OVERNIGHT AS WINDS DIMINISH...
WITH VSBYS FALLING TO 4-6 MILES 06Z-09Z. CIGS WILL REMAIN IN THE
VFR CATEGORY OVERNIGHT... MAINLY AOA 12K FEET.

ALTHOUGH CONDITIONS MAY REBOUND INTO VFR CATEGORY AGAIN BY 15Z
TUESDAY AS VSBYS IN FOG/HAZE IMPROVE... LOOK FOR CIGS TO LOWER
THROUGHOUT THE AFTERNOON WITH WIDESPREAD MVFR CIGS AND AREAS OF
LIGHT RAIN DEVELOPING BY LATE IN THE DAY.

RAIN WILL BECOME MIXED WITH SNOW AFTER 00Z... LIKELY BECOMING ALL
SNOW BY 06Z WEDNESDAY. THE OUTLOOK BEYOND 06Z WED IS FOR IFR SNOW
BECOMING MORE WIDESPREAD ESPECIALLY ALONG/NEAR I-94.

&&

.HYDROLOGY...
ISSUED AT 306 PM EDT MON MAR 10 2014

RUNOFF IN THE UPPER TRIBUTARIES OF THE RIVERS IN SOUTHWEST MI IS
INCREASING AS TEMPERATURES ARE IN THE 40S WHICH IS MELTING SOME
SNOW. WE HAVE SEEN SWE VALUES DROPPING OFF AT THE OBSERVATIONAL
SITES THIS AFTERNOON. RUNOFF WILL CONTINUE INTO TUE...SO WATER
LEVELS WILL BE RISING AT THE GAGING SITES. AT THIS TIME WE ARE NOT
EXPECTING IMPACTS FROM THIS RISE...HOWEVER WITH ICE IN THE RIVERS
THAT RAISES UNCERTAINTY. WILL NEED TO MONITOR TRENDS THROUGH THE
WEEK. ARCTIC AIR MOVES IN FOR WED...WHICH SHOULD LOCK UP THE
RUNOFF FOR A FEW DAYS.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...WINTER STORM WATCH FROM THIS EVENING THROUGH WEDNESDAY AFTERNOON
     FOR MIZ071>074.

LM...NONE.
&&

$$

SYNOPSIS...MJS
SHORT TERM...MJS
LONG TERM...JK
AVIATION...MEADE
HYDROLOGY...MJS