Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 280506
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1206 AM EST WED JAN 28 2015

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 256 PM EST TUE JAN 27 2015

AN AREA OF HIGH PRESSURE SITUATED OVER THE GREAT LAKES REGION WILL
KEEP THE WEATHER DRY THROUGH WEDNESDAY. LOW PRESSURE WILL TRACK
THROUGH THE REGION WEDNESDAY NIGHT AND THURSDAY. THIS SYSTEM COULD
LEAD TO SOME SLICK TRAVEL. A LARGE CANADIAN HIGH PRESSURE THEN
MOVES IN FOR FRIDAY AND SATURDAY.

&&

.SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT)
ISSUED AT 256 PM EST TUE JAN 27 2015

THE CHALLENGE DEALS WITH THE IMPACTS IF ANY FROM THE NEXT LOW
PRESSURE SYSTEM WEDNESDAY NIGHT AND THURSDAY.

MODELS VARY ON THE AMOUNT OF PRECIPITATION FORECASTED WITH THIS
EVENT WITH THE GFS SHOWING THE MOST. THIS MODEL FEATURES DEEPER
MOISTURE...WHILE THE NAM IS UNSATURATED AT TIMES IN THE DGZ.
THE HIGH RES EURO IS IN BETWEEN THE TWO. OVERALL THE PREVIOUS
FORECAST LOOKED GOOD AND IS SUPPORTED BY THE HIGH RES EURO...AND I
WILL NOT FEATURE MUCH IN THE WAY OF CHANGE. SOUTHWEST OF A GRAND
RAPID TO LANSING LINE AN ABOVE FREEZING ELEVATED DRY LAYER WILL
ALLOW FOR A MIX. THE AMOUNT OF COLD AIR NEAR THE GROUND SUPPORTS
MAINLY SLEET...BUT A RISK FOR FREEZING RAIN EXISTS. TOTAL QPF TO
REMAIN UNDER A QUARTER INCH. THUS CONSIDERING THE SURFACE
TEMPERATURES BELOW FREEZING AND SNOW OR MIXED PRECIPITATION
ARRIVING...IT APPEARS THAT MINOR IMPACTS WILL OCCUR.

NOT MUCH PRECIPITATION IS EXPECTED BEFORE 06Z THURSDAY AS THE
SOUNDINGS ARE SHOWN TO BE RELATIVELY DRY. BY 12Z THINGS MOISTEN UP
WITH THE DEEPER MOISTURE DEPARTING AFTER 18Z THU. THIS IS THE
WINDOW WHEN I WILL FEATURE THE HIGHEST POPS.

.LONG TERM...(FRIDAY THROUGH TUESDAY)
ISSUED AT 256 PM EST TUE JAN 27 2015

THE MAIN FOCUS OF THE LONG TERM PORTION OF THE FCST HAS NOW BECOME
THE LONG DURATION LIGHT SNOW EVENT FROM LATE SAT THROUGH MOST OF THE
DAY ON SUN. THIS DOES NOT LOOK TO PRODUCE MAJOR IMPACTS...BUT IT
WILL PRODUCE SOME IMPACTS FOR A SOMEWHAT EXTENDED PERIOD.

FRI CONTINUES TO LOOK LIKE SOME LAKE EFFECT WILL BE ONGOING WITH THE
COOLER AIR COMING IN BEHIND THE WED NIGHT/THU SYSTEM. H850 TEMPS
LOOK TO DROP DOWN INTO THE NEGATIVE MID-UPPER TEENS C PRODUCING
PLENTY OF SUFFICIENT INSTABILITY. THE COLD AIR WILL BE RATHER
SHALLOW HOWEVER AS THE UPPER JET LIFTS OUT FAIRLY QUICKLY...ALLOWING
INVERSION HEIGHTS TO DROP PRETTY GOOD BY FRI.

WE HAVE MUCH BETTER CONFIDENCE THAT A GOOD PORTION OF THE AREA WILL
SEE LIGHT ACCUMULATING SNOW FROM LATE SAT THROUGH SUN NIGHT. THE
UPPER LOW TAKING SHAPE OVER THE DESERT SW WILL LIFT NE AND TAP GULF
MOISTURE OUT AHEAD OF IT. RIGHT NOW WE ARE EXPECTING WEAK FORCING
WITH THE ELEVATED WARM AND MOIST ADVECTION TO TAKE PLACE FOR AN
EXTENDED PERIOD. ONE THING TO WATCH WITH THIS SYSTEM IS IF THE NRN
WAVE COMING IN BEHIND IT WERE TO PHASE EARLIER AND BETTER. IF IT
WERE TO DO THIS...WE COULD SEE A BIGGER STORM FOR OUR AREA. IT LOOKS
TO BE MORE OF A PLAYER FOR THE EAST COAST FOR NOW.

WE WILL SEE THE COLDER AIR THEN COME IN BEHIND THE SAT/SUN SYSTEM AS
THE NRN STREAM SYSTEM MOVES THROUGH. WE WILL TRANSITION TO A NW FLOW
LAKE EFFECT REGIME FOR THE PERIOD FROM MON THROUGH TUE. THE LAKE
EFFECT MAY HOLD MORE OF A PUNCH FOR MON AS CYCLONIC FLOW AND THE
COLD POOL ALOFT IS OVERHEAD. THE TROUGH THEN IS EXPECTED TO LIFT OUT
BY TUE...HELPING TO DIMINISH THE INTENSITY OF THE LAKE EFFECT.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1159 PM EST TUE JAN 27 2015

VFR WEATHER WILL CONTINUE OVERNIGHT AND WEDNESDAY WITH CLOUD
BASES AOA 10K FT AND SFC WINDS GENERALLY UNDER 10 KTS. AT MKG
HOWEVER THE WINDS SHOULD INCREASE TO 10-15 KTS ON WEDNESDAY AND
SOME SCATTERED MVFR LAKE CLOUDS MAY IMPACT THE TERMINAL FOR A
BRIEF TIME.

AFTER 00Z THURSDAY THE SFC WINDS WILL INCREASE TO 10-20 KTS FROM
THE SOUTH-SOUTHEAST AND SOME POTENTIAL FOR LLWS WILL DEVELOP AS
WINDS AT 3000 FT STRENGTHEN TO 40-50 KTS.

THE OUTLOOK BEYOND 06Z THURSDAY IS FOR A MIX OF SLEET...FREEZING
RAIN AND SNOW TO DEVELOP. THIS WILL LEAD TO ICING CONCERNS FOR
AVIATION INTERESTS.

&&

.HYDROLOGY...
ISSUED AT 1215 PM EST TUE JAN 27 2015

A FEW AREA RIVERS SHOWED MINOR FLUCTUATIONS OVER THE PAST 48 HOURS.
NONE OF THIS WAS TOO CONCERNING. THE ACTIVITY HAS SEEMED TO LEVEL
OFF AND STABILIZE FOR THE MOST PART. COLDER TEMPERATURES WILL HOLD
ON THROUGH MUCH OF THE WEEK WITH THE WARMEST CONDITIONS BEING FELT
THURSDAY...TO THE TUNE OF LOW TO MID 30S.

A COUPLE ROUNDS OF WINTRY PRECIPITATION ARE POSSIBLE. THE TWO MAIN
EVENTS ANTICIPATED ARE LATE WEDNESDAY INTO THURSDAY AND AGAIN BY
SUNDAY. MOISTURE WILL BE SPREAD OUT OVER TIME AND COLDER TEMPERATURES
DO NOT LOOK TO BE CAUSE FOR CONCERN. RIVERS WILL CONTINUE TO BE
MONITORED IN THE CASE THAT ANY FLUCTUATION DOES OCCUR.

&&

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

$$

SYNOPSIS...MJS
SHORT TERM...MJS
LONG TERM...NJJ
AVIATION...MEADE
HYDROLOGY...JAM






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