Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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000
FXUS63 KGRR 251140
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
640 AM EST SUN JAN 25 2015

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 300 AM EST SUN JAN 25 2015

AN ALBERTA CLIPPER SYSTEM WILL PASS BY TO THE SOUTH OF LOWER
MICHIGAN TODAY. A FEW VERY LIGHT SNOW SHOWERS AND FLURRIES ARE
ANTICIPATED ALONG THE INTERSTATE 94 CORRIDOR THIS MORNING BUT WITH
VERY LITTLE TO NO SNOW ACCUMULATION. IT WILL TURN COLDER BEHIND
THAT SYSTEM FOR MONDAY WITH A FEW LIGHT SNOW SHOWERS AND FLURRIES
POSSIBLE LATE MONDAY AND MONDAY NIGHT. TEMPERATURES WILL MODERATE
FOR THE MIDDLE PART OF NEXT WEEK.

&&

.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 300 AM EST SUN JAN 25 2015

A CONSENSUS OF LATEST SHORT RANGE GUIDANCE AND TRENDS THE PAST 24
TO 48 HRS CONTINUES TO SUGGEST THAT THE ALBERTA CLIPPER WILL PASS
BY TO THE SOUTH OF LWR MI.

A FEW VERY LIGHT SNOW SHOWERS AND FLURRIES MAY CLIP FAR SOUTHERN LWR
MI ALONG THE I-94 CORRIDOR THIS MORNING. HOWEVER EVEN ALONG I-94
THERE WILL BE VERY LITTLE TO NO SNOW ACCUMULATION. SLOWLY FALLING
TEMPS ARE ANTICIPATED LATER THIS MORNING THROUGH THE AFTERNOON.

HIGH PRESSURE WILL BUILD IN TONIGHT WHICH IN CONJUNCTION WITH NE
WINDS WILL ALLOW SKIES TO BECOME PARTLY CLOUDY TO MOSTLY CLEAR.
TEMPS OVERNIGHT WILL FALL INTO THE SINGLE DIGITS TO LOWER TEENS
ACROSS OUR AREA.

A VERY WEAK CLIPPER SYSTEM MAY BRING A FEW LIGHT SNOW SHOWERS AND
FLURRIES LATE MONDAY AND MONDAY NIGHT BUT WITH VERY LITTLE TO NO
SNOW ACCUMULATION. MAX TEMPS MONDAY WILL ONLY REACH THE UPPER
TEENS TO LOWER 20S.

A RIDGE OF HIGH PRESSURE WILL BRING FAIR WX AND PARTIAL CLEARING ON
TUESDAY AS SUGGESTED BY 00Z GUIDANCE TIME HEIGHT RH X-SECTIONS. MAX
TEMPS TUESDAY WILL REACH THE UPPER 20S TO LOWER 30S.

.LONG TERM...(TUESDAY NIGHT THROUGH SATURDAY)
ISSUED AT 300 AM EST SUN JAN 25 2015

PRIMARY CONCERNS REVOLVE AROUND PROSPECTS FOR ACCUMULATING SNOW
THURSDAY AND THE ARRIVAL OF MORE ARCTIC AIR FOR LATE IN THE WEEKEND.
OVERALL IT LOOKS MORE LIKELY THAN NOT THAT MUCH OF THE REGION
WILL SEE 2 TO 3 INCHES OF SNOW WITH PERHAPS 4 INCHES IN SPOTS FOR
THURSDAY. THIS SNOW IS EXPECTED TO IMPACT BOTH THE THURSDAY MORNING
AND THURSDAY EVENING COMMUTES. THE EXPECTATION IS THE PRECIP WILL
STAY ALL SNOW AT THIS POINT.

CURRENT CLOSED LOW OFF BAJA CALIFORNIA WILL MOVE NORTHWARD AS
RIDGING OVER THE FOUR CORNERS REGION BREAKS DOWN. MEDIUM RANGE
GUIDANCE IS IN VERY GOOD AGREEMENT ABOUT THIS SYSTEM PHASING WITH A
NORTHERN STREAM H500 SHORTWAVE AND HEADING TOWARD THE MIDWEST AS AN
ALBERTA CLIPPER. THE GFS AND GEM ARE IN LOCK STEP WITH THE TIME OF
ARRIVAL AND EXIT OF THIS SYSTEM ACROSS THE GREAT LAKES WHILE THE
ECMWF SHOWS A DEEPER TROUGH AND HENCE A SLOWER TRANSLATION TO THE
CLIPPER ACROSS OUR AREA. A CONSENSUS OF MODEL QPF CALLS FOR 0.25 TO
0.33 INCH WITH THIS SYSTEM...YIELDING 2 TO 3 INCHES AND PERHAPS A
BIT MORE IN SPOTS. WHILE NOT A SUBSTANTIAL AMOUNT OF SNOW...IT WILL
LIKELY BE SNOWING MUCH OF THE DAY THURSDAY...WITH SOME SLICK ROADS
FORESEEN FOR THE THURSDAY MORNING AND EVENING COMMUTES.

THE 00Z ECMWF IS MUCH QUICKER WITH THE ARRIVAL OF H850 -25C
AIR...NOW SHOWING IT BY SATURDAY EVENING. THE GFS IS OVER 24 HOURS
LATER WITH THE ARRIVAL OF THE ARCTIC AIR...AND A BIT WARMER.
HOWEVER...BOTH OF THE 00Z SOLUTIONS BOOT THE CORE OF THE COLDEST AIR
OUT VERY QUICKLY. UNCERTAIN AT THIS POINT EXACTLY WHEN THAT AIR
ARRIVES AND HOW LONG IT WILL LAST. HIGHS IN THE SINGLE DIGITS AND
TEENS STILL LOOK POSSIBLE IF WE ACTUALLY GET INTO THE MID -20S C OR
COLDER AT H850...BUT CONFIDENCE IS NOT GREAT ON JUST HOW COLD IT
WILL GET AT THIS POINT GIVEN DIFFERENCES IN TIMING AND SEVERITY OF
THE COLD...DUE TO MODEL RUN-TO-RUN CONSISTENCY ISSUES.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 634 AM EST SUN JAN 25 2015

BOOSTED WINDS UP A FEW KNOTS COMPARED TO 06Z TAF ISSUANCE. THIS IS
BASED ON LATEST OBSERVATIONS AND MODEL GUIDANCE FOR TODAY. IFR
SEEMS TO DOMINATE AT LEAST THROUGH EARLY AFTERNOON FOR AZO/BTL/JXN
ALTHOUGH TRANSIENT CHANGES TO MVFR MAY OCCUR AT TIMES...WHICH HAS
OCCURRED EARLY THIS MORNING. LIGHT SNOW SHOWERS ARE NOT EXPECTED
TO REDUCE VISIBILITIES BELOW 3 MILES. IMPROVING CONDITIONS ARE
FORESEEN LATER THIS AFTERNOON AND EVENING.



&&

.HYDROLOGY...
ISSUED AT 318 PM EST SAT JAN 24 2015

A SLIGHT AMOUNT OF SNOW MELT OBSERVED TODAY BUT NOT ENOUGH TO BE A
CONCERN. ICE ON THE RIVERS IS NOT MOVING AND WATER LEVELS ARE
HOLDING STEADY IF NOT DROPPING SLIGHTLY. SNOW AND COLD TEMPERATURES
FOR THE COMING WEEK WILL KEEP THINGS IN PLACE. CURRENTLY NO
SUSPECTED ICE JAMS IN THE AREA... BUT WILL CONTINUE MONITORING FOR
ANY THAT DO DEVELOP. SERIOUS ICE JAMS AND FLOODING CONCERNS ARE
UNLIKELY UNTIL A SIGNIFICANT WARM UP AND RAINFALL... WHICH IS
CONFIDENTLY NOT ON THE 1-2 WEEK HORIZON.

&&

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

$$

SYNOPSIS...LAURENS
SHORT TERM...LAURENS
LONG TERM...HOVING
AVIATION...HOVING
HYDROLOGY...CAS





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