Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 270255
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
955 PM EST MON JAN 26 2015

LATEST UPDATE...
UPDATE

.SYNOPSIS...
ISSUED AT 302 PM EST MON JAN 26 2015

A RIDGE OF HIGH PRESSURE WILL BUILD INTO LOWER MICHIGAN TONIGHT
AND TUESDAY PROVIDING THE REGION WITH GENERALLY DRY AND COLD
WEATHER. THIS SYSTEM WILL REMAIN OVER THE AREA THOUGH WEDNESDAY
BEFORE TRACKING INTO NEW ENGLAND ON THURSDAY. THIS WILL ALLOW A
LOW PRESSURE SYSTEM TO MOVE IN TO THE GREAT LAKES REGION FOR
THURSDAY RESULTING IN UNSETTLED WEATHER.

&&

.UPDATE...
ISSUED AT 954 PM EST MON JAN 26 2015

TWEAKED MIN TEMPS UPWARD A BIT TONIGHT. CLOUDS CONTINUE TO SPREAD
IN AND ONCE THIS HAPPENS TEMPS WILL STAY FAIRLY LEVEL THE REST OF
THE NIGHT. ALSO ADDED 20 POPS FURTHER INLAND AS AN AREA OF SNOW
OVER THE DOOR PENINSULA AT 0230Z SEEMS AIMED FOR THE CENTRAL GRR
CWA. EVEN SO...ANY SNOW WILL BE LIGHT WITH LITTLE TO NO
ACCUMULATION. ALSO NOT OUT OF THE QUESTION THAT SOME LIGHT
SNOW/FLURRIES MOVES OFF OF LAKE HURON TOWARD CLARE/ISABELLA
COUNTIES AS THE MEAN LOW FLOW BECOMES MORE ENE LATER TONIGHT.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY) ISSUED AT 302 PM
EST MON JAN 26 2015

OVERALL THE FORECAST WILL BE RATHER QUIET THROUGH THE SHORT TERM.
THE WEAK AREA OF LOW PRESSURE OVER WESTERN WI...TRACKS SOUTH DUE
TO THE BLOCKING STORM DEVELOPING OFF THE MID ATLANTIC. THUS LOWER
MICHIGAN WILL SEE A RIDGE OF HIGH PRESSURE MOVE IN. AS THE SNOW IN
WISCONSIN TRIES TO MOVE IN TONIGHT AND TUESDAY...IT WILL LIKELY
DRY UP GIVEN THE LOW LEVEL DRY AIR MASS THAT WILL BE IN PLACE. WE
WILL HOWEVER MAINTAIN A VERY LOW POP FOR THE LAKESHORE COMMUNITIES.

WE DID LOWER TEMPERATURES TUESDAY NIGHT. SUBSIDENCE SHOULD SUPPORT
DIMINISHING CLOUDS. WITH A LOW LEVEL THERMAL TROUGH AROUND...IT
SHOULD ALLOW FOR RATHER COLD TEMPERATURES.

.LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY)
ISSUED AT 302 PM EST MON JAN 26 2015

THE MAIN ITEMS OF INTEREST IN THE LONG TERM CONTINUE TO BE THE TWO
SYSTEMS THAT WILL POTENTIALLY AFFECT THE AREA WED NIGHT/THU AND
SAT... AND EVENTUALLY THE COLD AIR THAT IS EXPECTED TO MOVE IN AT
SOME POINT LATE IN THE WEEKEND AND EARLY NEXT WEEK. WE ARE NOW ALSO
LOOKING AT SOME POSSIBLE SNOW FOR SUN THAT HAS CROPPED UP IN SOME
MODEL RUNS.

THE WED NIGHT THU SYSTEM REMAINS LARGELY ON TRACK WITH PREVIOUS
FCSTS. LIGHT SNOW IS EXPECTED TO MOVE IN DURING THE LATTER HALF OF
WED NIGHT AND CONTINUE INTO THE DAY ON THU. ONE CHANGE THAT WE HAVE
MADE TO THU IS TO ADD IN A MIX OF RAIN/SNOW ACROSS THE SOUTH ON THU
AS THE LATEST TRENDS ARE TO BRING JUST ENOUGH WARM AIR INTO THE SRN
COUNTIES TO BRING A CHC OF SOME RAIN MIXING IN. FCST WET BULB ZERO
HEIGHTS SUPPORT THIS IDEA. WE ARE STILL THINKING A GENERAL 1-3
INCHES OR SO WITH THIS. ANY RAIN DOWN SOUTH WOULD CUT BACK ON SNOW
ACCUMULATIONS THERE.

WE SHOULD SEE A RELATIVELY QUIET DAY ON FRI WITH HIGH PRESSURE OVER
THE AREA...BEFORE ANOTHER CHC OF SNOW MOVES IN ON SAT. SOME NUISANCE
TYPE LAKE EFFECT WILL BE POSSIBLE RIGHT ALONG THE SHORELINE WITH A
NNW FLOW AND OVER LAKE INSTABILITY MARGINAL FOR LAKE EFFECT.
INVERSION HEIGHTS AND MOISTURE DEPTH LOOKS QUITE LIMITED STILL WITH
THE RIDGE OVERHEAD.

A FAIR AMOUNT OF UNCERTAINTY REMAINS FOR THE WEEKEND AND EARLY NEXT
WEEK. THE MODELS HAVE TRENDED FURTHER NORTH WITH THE CLIPPER SYSTEM
ON SAT...WHICH WOULD SUPPORT LESS OF A CHC OF SNOW AND A DELAY IN
THE COLDER ARCTIC AIR MOVING IN. THIS LOOKS TO BE THE RESULT OF THE
STRONG TROUGH/LOW DIGGING ACROSS THE DESERT SW AND THE RESULTING
RIDGE DOWNSTREAM OF IT. THIS WOULD KEEP THE TROUGH COMING IN FROM
CANADA FROM DIGGING AS MUCH. THERE ARE SOME INDICATIONS THAT THE
SNOW ON THE NRN PERIPHERY OF THE SRN SYSTEM COULD SNEAK IN HERE FOR
SUN. THE COLD AIR WOULD EVENTUALLY FILTER IN AS NRLY FLOW DOES
DEVELOP. THE FLOW COULD EVEN GO NE DEPENDING ON THE EXACT EVOLUTION
OF THE SFC RIDGE. THIS WOULD LIMIT THE LAKE EFFECT WITH THE COLD
AIR. WE WILL CONTINUE TO MONITOR FUTURE TRENDS.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 652 PM EST MON JAN 26 2015

VFR CONDITIONS ARE EXPECTED OVER THE NEXT 24 HOURS. SURFACE LOW
PRESSURE OVER WESTERN WI AND SE MN WILL SLIP SSE DOWN THE
MISSISSIPPI RIVER VALLEY OVERNIGHT. THIS FEATURE WILL KEEP MID
LEVEL CLOUDS BASED AROUND 8K FEET OVER LOWER MI THROUGH MIDDAY
TUESDAY. EASTERN WI SITES REPORTING LIGHT SNOW AND THERE ARE SOME
LIGHT ECHOES OVER LAKE MICHIGAN...BUT THERE IS TOO MUCH DRY AIR AT
THE SURFACE TO OVERCOME.

WINDS WILL CONTINUE TO TURN MORE NORTHEASTERLY OVERNIGHT AND
EVENTUALLY NORTHERLY BY MIDDAY TUESDAY. WINDS WILL REMAIN BELOW 10
KTS.


&&

.HYDROLOGY...
ISSUED AT 302 PM EST MON JAN 26 2015

GENERAL STEADY OR SLOWLY DROPPING RIVER LEVELS ACROSS THE AREA WITH
A FEW RIVERS SHOWING BIGGER FLUCTUATIONS OVER THE PAST DAY... BUT
NONE ARE CURRENTLY THREATENING TO REACH BANKFULL. COLD TEMPERATURES
FOR THE COMING WEEK WILL KEEP THE ICE LOCKED UP. CURRENTLY NO
SUSPECTED ICE JAMS IN THE AREA... BUT WILL CONTINUE MONITORING FOR
ANY THAT MIGHT DEVELOP. SERIOUS ICE JAMS AND FLOODING CONCERNS ARE
UNLIKELY UNTIL A SIGNIFICANT WARM UP AND RAINFALL.

&&

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

$$

UPDATE...JK
SYNOPSIS...MJS
SHORT TERM...MJS
LONG TERM...NJJ
AVIATION...EBW
HYDROLOGY...CAS






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