Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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000
FXUS63 KGRR 310005
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
705 PM EST FRI JAN 30 2015

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 328 PM EST FRI JAN 30 2015

LOW PRESSURE WILL BRING SOME SNOW ON SUNDAY WITH THE HIGHEST
AMOUNTS ACROSS FAR SOUTHERN LOWER MICHIGAN NEAR THE INDIANA
BORDER. VERY COLD WEATHER IS EXPECTED MONDAY WITH MORE SNOW
POSSIBLE TUESDAY NIGHT AND WEDNESDAY.

&&

.SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT)
ISSUED AT 328 PM EST FRI JAN 30 2015

THE STORM ON SUNDAY IS THE MAIN FORECAST PROBLEM IN THE NEAR TERM.
12Z MODEL GUIDANCE CONTINUES TO SHOW THE POTENTIAL FOR 4 OR MORE
INCHES OF SNOW ACROSS THE I-94 CORRIDOR BETWEEN SATURDAY NIGHT AND
SUNDAY NIGHT. HELD OFF ON HEADLINES FOR NOW BASED ON UNCERTAINTY
THAT THE RECENT MORE NORTHERLY JOG WILL LAST...ALTHOUGH THE CURRENT
TREND IS DEFINITELY IN THAT DIRECTION.

THE SYNOPTIC SET UP IS SIMILAR TO LAST SUNDAY WITH A COLD AND DRY
AIR MASS TO THE NORTH AND A LOW PASSING THROUGH THE OHIO VALLEY.
ONCE AGAIN WE EXPECT A SHARP SNOWFALL GRADIENT AS MESOSCALE BANDS
WILL ALIGN EAST TO WEST ACROSS THE SOUTHERN FORECAST AREA IN AREA OF
MID LEVEL F-GEN FORCING. WE BUMPED UP THE POPS AND QPF FOR SATURDAY
NIGHT THROUGH SUNDAY NIGHT WITH THE BULK OF THE SNOW FALLING SUNDAY
MORNING. SOME INCH AN HOUR RATES ARE POSSIBLE ACROSS THE FAR SOUTH
SUNDAY MORNING INTO THE AFTERNOON.

THE LOW IS CURRENTLY GATHERING STRENGTH ACROSS THE SOUTHWEST CONUS
AND IS BEING FED BY A DEEP PLUME OF TROPICAL MOISTURE FROM THE
EASTERN PACIFIC. THE LOW WILL ALSO GET GOOD GULF OF MEXICO INFLOW AS
IT MOVES EAST. MEANWHILE...EASTERLY FLOW DEVELOPS AHEAD OF THE
SYSTEM AND A MATURE CYCLONE WITH WARM AND COLD CONVEYOR BELTS TRACKS
ACROSS THE OHIO VALLEY WITH 12Z MODEL GUIDANCE SHOWING ENOUGH QPF TO
COME CLOSE TO WARNING CRITERIA ACROSS THE FAR SOUTH. SNOW TOTALS
WILL PROBABLY END UP 20 TO 1 OR GREATER GIVEN THE COLD AIR IN PLACE
DURING THIS EVENT.

.LONG TERM...(MONDAY THROUGH FRIDAY)
ISSUED AT 328 PM EST FRI JAN 30 2015

VERY COLD WEATHER WILL CONTINUE MONDAY WITH POTENTIAL FOR SINGLE
DIGIT BELOW TO ABOVE ZERO READINGS EARLY MONDAY MORNING. MAX TEMPS
WILL ONLY REACH THE TEENS MONDAY IN SPITE OF SOME SUN WITH HIGH
PRESSURE IN CONTROL. THE NEXT LOW PRESSURE SYSTEM AND PV ANOMALY
WILL BRING POTENTIAL FOR LAKE ENHANCED SNOW TUESDAY THROUGH TUESDAY
NIGHT.

THE COLD FRONT SHOULD BE THROUGH OUR AREA BY WEDNESDAY MORNING WITH
ANOTHER INTRUSION OF ARCTIC AIR AND BELOW NORMAL TEMPS FROM
WEDNESDAY NIGHT THROUGH LATE WEEK. A FEW LIGHT LAKE EFFECT SNOW
SHOWERS AND FLURRIES ARE POSSIBLE LATE IN THE WEEK.

OVERALL THOUGH THE SETUP DOES NOT LOOK FAVORABLE FOR LAKE EFFECT
SNOW OF ANY SIGNIFICANCE LATE IN THE WEEK DUE TO THE VERY DRY ARCTIC
AIRMASS AND DRY FCST SOUNDINGS THURSDAY/FRIDAY AS WELL AS VERY LOW
INVERSION HEIGHTS BY THEN. MAX TEMPS THURSDAY AND FRIDAY WILL ONLY
REACH THE TEENS.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 700 PM EST FRI JAN 30 2015

LOW CONFIDENCE WITH RESPECT TO EXTENT/COVERAGE OF MVFR CLOUDS
TONIGHT AND SATURDAY. AT 7 PM FRIDAY THERE IS AN AREA OF LAKE
EFFECT CLOUDS WITH BASES AROUND 2500 FT FROM MKG/BIV TO AZO. THIS
AREA OF CLOUDS IS MOVING TO THE EAST NOW THAT THE LOW LEVEL FLOW
IS BACKING. AS THE CLOUDS CONTINUE TO THE EAST... BTL AND GRR MAY
BECOME MVFR FOR AWHILE THIS EVENING.

NOT SURE IF THE MVFR CLOUDS WILL EVER COMPLETELY GO AWAY LATER TONIGHT
AND SATURDAY. IN FACT THE NAM GUIDANCE IS SUGGESTING RATHER
WIDESPREAD COVERAGE OF LOW CLOUDS DEVELOPING ON SATURDAY...
ESPECIALLY IN THE AFTERNOON AS DEW POINTS RISE IN THE SOUTHWEST
FLOW LEVEL FLOW OF AROUND 10-15 KTS AHEAD OF THE APPROACHING SFC COLD
FRONT. SINCE THE NAM TYPICALLY DOES WELL WITH LOW LEVEL MOISTURE
TRENDS... WILL FEATURE MVFR CLOUDS AT ALL THE TERMINALS AFTER 18Z
SATURDAY. BEFORE THAT...A MIX OF MVFR/VFR IS EXPECTED AND
DEPENDENT ON THE BEHAVIOR OF THE EXISTING AFOREMENTIONED LAKE
CLOUDS.

&&

.HYDROLOGY...
ISSUED AT 318 AM EST FRI JAN 30 2015

ICE FORMATION IS THE MAIN CONCERN DURING THE NEXT FEW DAYS. HIGHS AROUND
20 TODAY AND AROUND 15 SUNDAY AND MONDAY WILL BE FAVORABLE FOR ICE
DEVELOPMENT.

&&

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

$$

SYNOPSIS...OSTUNO
SHORT TERM...OSTUNO
LONG TERM...LAURENS
AVIATION...MEADE
HYDROLOGY...93





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