Area Forecast Discussion
Issued by NWS Grand Rapids, MI

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS63 KGRR 240830
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
330 AM EST MON NOV 24 2014

LATEST UPDATE...
SYNOPSIS/SHORT TERM/LONG TERM

.SYNOPSIS...
ISSUED AT 330 AM EST MON NOV 24 2014

RAIN ONGOING EARLY THIS MORNING WILL DIMINISH A BIT IN COVERAGE
AND INTENSITY THIS MORNING. INTERVALS OF RAIN WILL CONTINUE
THROUGH MID AFTERNOON ACROSS THE AREA BEFORE ALL RAIN CHANGES TO
SNOW FAIRLY RAPIDLY LATE THIS AFTERNOON INTO EARLY THIS EVENING.
SNOW WILL ACCUMULATE ACROSS THE AREA FROM TONIGHT THROUGH
TUESDAY...WITH THE HIGHEST AMOUNTS OCCURRING TO THE NORTHWEST
TOWARD LUDINGTON.

WE WILL SEE A BREAK IN THE SNOW FROM LATE TUESDAY NIGHT INTO
WEDNESDAY BEFORE SNOW SHOWERS WILL BECOME POSSIBLE ONCE AGAIN.
THERE WILL BE AT LEAST A CHANCE OF SNOW FOR THANKSGIVING AND INTO
THE WEEKEND...HOWEVER NO SIGNIFICANT SNOWFALL IS EXPECTED LATER
THIS WEEK. A MODERATION IN TEMPERATURES AND PRECIPITATION CHANGING
OVER TO RAIN WILL BE POSSIBLE NEXT WEEKEND.

&&

.SHORT TERM...(TODAY THROUGH TUESDAY NIGHT)
ISSUED AT 330 AM EST MON NOV 24 2014

WE HAVE ISSUED A WIND ADVISORY FOR THIS AFTERNOON AND EARLY
EVENING FOR ROUGHLY THE SE HALF OF THE FCST AREA. A WINTER WEATHER
ADVISORY HAS BEEN ISSUED FOR ROUGHLY THE NW HALF OF THE AREA FOR
LATE THIS AFTERNOON THROUGH THE DAY ON TUESDAY.

STEADY RAIN CONTINUES TO FALL ACROSS THE AREA EARLY THIS MORNING
WITH THE DRY SLOT TRYING TO MAKE IT INTO THE FCST AREA FROM THE
SOUTH. WE ARE SEEING THE MODERATE RAIN THAT FELL LAST EVENING SHIFT
OUT OF THE AREA AS THE CORE OF THE LLJ AHEAD OF THE LOW SHIFTS EAST
OF THE AREA. THE DRY SLOT SHOULD STAY JUST SOUTH OF THE CWFA
BORDER...KEEPING PERIODS OF RAIN/SHOWERS MOVING THROUGH THE AREA
TODAY. THE AREA OF SHOWERS MOVING ACROSS SRN IL AS OF 08Z THIS
MORNING WILL BE THE LAST OF THE WIDESPREAD RAIN FOR THE AREA THAT
WILL MOVE THROUGH LATE THIS MORNING AND INTO THE AFTERNOON HOURS.

THE WINDS ARE LIGHT RIGHT NOW ACROSS THE AREA...BUT WILL INCREASE
LATE THIS MORNING/EARLY THIS AFTERNOON ACROSS THE SE PORTION OF THE
CWFA. THE BAND OF SHOWERS ACROSS SRN IL IS WITH A SFC WAVE THAT WILL
MOVE UP INTO THE AREA. ONCE THIS WAVE MOVES BY...THE COLD AIR
ADVECTION WILL COMMENCE AS THE STRONGER GRADIENT MOVES IN. MODELS
INDICATE THAT 40 KNOTS OR SO AROUND 2K FT WILL BE VERY ABLE TO BE
MIXED DOWN WITH THE GOOD MIXING DUE TO THE COLD AIR ADVECTION.

WE WILL SEE ALL RAIN CHANGE OVER TO SNOW FAIRLY QUICKLY FROM SW TO
NE AFTER 21Z AND ALMOST ACROSS THE ENTIRE AREA TOWARD 00Z. WE WILL
SEE THE BAND OF PCPN COMING UP AHEAD OF THE SRN IL WAVE MOVE NORTH
AND ALMOST BECOME STATIONARY ACROSS THE NW HALF OF THE CWFA. THIS
OCCURS INITIALLY WITH AN INITIAL DEFORMATION BAND FROM THE UPPER
WAVE COMING IN FROM THE SW. WE WILL THEN SEE THE NEXT SHORT WAVE
WITH THE PARENT TROUGH ROTATE IN ACROSS THE AREA AND FAVOR THE NW
COUNTIES ONCE AGAIN. BY THIS TIME...IT WILL BE SNOWING AND WILL
ACCUMULATE.

THIS SNOW WILL AFFECT THE NW HALF OF THE CWFA FROM THIS EVENING INTO
EARLY TUE AFTERNOON WHEN A THIRD SHORT WAVE MOVES THROUGH IN THE
SAME FASHION. WE ARE LOOKING AT A PROLONGED LIGHT SNOW EVENT WITH
SOME ENHANCEMENT AT TIMES DUE TO A SW FLOW OFF OF THE LAKE. DELTA
T/S WILL BE IN THE TEENS AND MOISTURE WILL BE QUITE DEEP OVER THE
AREA. WHAT WILL KEEP THIS FROM BEING A MORE SIGNIFICANT EVENT WILL
BE AN INVERSION THAT FLUCTUATES FROM 5-8K FT. THIS WILL LIMIT THE
LAKE ENHANCEMENT FROM BECOMING TOO STRONG...BUT SOME LOCALLY HEAVIER
AMOUNTS WILL STILL BE POSSIBLE. SOME UPSLOPE FLOW ACROSS THE HILLS
OF CENTRAL LOWER COULD ALSO HELP TOTALS A BIT. SOME BLOWING AND
DRIFTING WILL BE POSSIBLE TOWARD THE LAKESHORE WHERE WINDS WILL BE A
LITTLE STRONGER.

AS THE MAIN UPPER TROUGH FINALLY PULLS OUT TUE AFTERNOON...WE WILL
SEE SNOW SHOWERS DIMINISH. THERE COULD BE SOME DECENT BANDS MOVE
THROUGH GRR TUE MORNING AS THE FLOW BECOMES MORE WNW BEFORE
EVERYTHING ENDS LATE TUE. AMOUNTS WILL BE LOWER TOWARD GRR...HOWEVER
THE TUE MORNING COMMUTE COULD BE IMPACTED.

.LONG TERM...(WEDNESDAY THROUGH SUNDAY)
ISSUED AT 330 AM EST MON NOV 24 2014

OTHER THAN THE POSSIBILITY OF SOME LIGHT LAKE EFFECT SNOW
ACCUMULATIONS ON THANKSGIVING DAY... CONFIDENCE IS INCREASING THAT
MINIMAL TRAVEL IMPACTS WILL OCCUR OVER THE UPCOMING HOLIDAY PERIOD.

MODELS HAVE TRENDED MUCH FARTHER SOUTH WILL THE CLIPPER LOW ON
WEDNESDAY AND WEDNESDAY NIGHT SO THE SYNOPTIC SNOW POTENTIAL WITH
THAT SYSTEM NOW LOOKS QUITE LOW.

H8 AIR AROUND -15C IS STILL PROGGED TO COME INTO THE AREA VIA
NORTHWEST WINDS ON THANKSGIVING DAY. CONDITIONS LOOK FAVORABLE FOR
LAKE EFFECT SNOW FOR ABOUT 12 HOURS AS H5 SHORTWAVE PIVOTS
THROUGH... SO A FEW INCHES OF ACCUMULATION STILL APPEARS POSSIBLE
NEAR AND WEST AND HIGHWAY 131. SURFACE RIDGING AND WARM ADVECTION
ARRIVES THURSDAY NIGHT AND THE LAKE EFFECT SHOULD DIMINISH AT THAT
TIME.

AFTER THANKSGIVING DAY... THE UPPER FLOW GOES FLAT/ZONAL WITH 100 KT
PACIFIC JET SHOOTING ACROSS THE NRN CONUS. THIS PATTERN WILL LEAD TO
MILDER TEMPERATURES DEVELOPING ACROSS SW MI TOWARD THE END OF THE
WEEK WITH ONLY A SMALL CHANCE FOR LIGHT SNOW OR MIXED LIGHT RAIN AND
SNOW.

LATEST 00Z GUIDANCE NOW SHOWS A RATHER STRONG WARM ADVECTION PATTERN
ON SATURDAY AHEAD OF A NRN PLAINS LOW... SO WE MAY NEED TO BOOST
HIGHS INTO THE 40S IF THIS TREND REMAINS. THAT SAME SYSTEM DRAGS A
COLD FRONT THROUGH ON SATURDAY NIGHT OR EARLY SUNDAY AS IT MOVES
EAST... BUT NOT MUCH QPF ALONG THE FRONT AND STRONG SURFACE RIDGING
DEVELOPING BEHIND IT ON SUNDAY.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1156 PM EST SUN NOV 23 2014

IMPACTS TO AVIATORS WILL CONTINUE. IFR OR LOWER TO PREVAIL INTO
MONDAY AS A LOW PRESSURE SYSTEM TRACKS THROUGH.

COLDER AIR WILL WRAP IN FROM THE WEST TO SOUTHWEST ON MONDAY
CHANGING MUCH OF THE PRECIPITATION OVER TO SNOW. HOWEVER DOWN
TOWARD KAZO...KBTL AND KJXN THERE IS AN INCREASED RISK FOR ICING
GIVEN THE LIMITED MOISTURE DEPTH. ALSO THOSE SOUTHERN TAF SITES
SHOULD SEE STRONGER WINDS DEVELOPING AS WE HEAD THROUGH THE
AFTERNOON. GUSTS OVER 30 KNOTS POSSIBLE. A SMALL RISK FOR
THUNDERSTORMS EXISTS FOR KJXN IN THE 16Z TO 19Z TIMEFRAME. I WAS
NOT CONFIDENT ENOUGH TO FEATURE IT IN THE FORECAST.

SOME OF THE SNOW LATER MON AFTERNOON INTO THE EVENING COULD END UP
PRODUCING LOWER THAN IFR...PRIMARILY FOR KGRR AND KMKG.


&&

.MARINE...
ISSUED AT 327 PM EST SUN NOV 23 2014

LOW PRESSURE WILL MOVE OVER LOWER MICHIGAN MONDAY/MONDAY NIGHT. A
TRAILING TROUGH IS PROGD TO SET UP ACROSS WESTERN LOWER MICHIGAN.
THE MODELS ARE NOT CONSISTENT IN WHERE THIS TROUGH WILL END UP. AS
SUCH PINNING DOWN WHERE THE GRADIENT OF HIGHEST WINDS WILL BE IS
ALSO DIFFICULT. ULTIMATELY...WE ISSUED A GALE WARNING SOUTH OF GRAND
HAVEN AND LEFT THE WATCH NORTH OF THERE.

&&

.HYDROLOGY...
ISSUED AT 327 PM EST SUN NOV 23 2014

REGIONAL RADAR SHOWS RAIN SPREADING NORTHWARD FROM THE SOUTHERN US.
QPF AROUND AN INCH IS POSSIBLE FROM LATER THIS AFTERNOON THROUGH
MONDAY BEFORE THE PCPN CHANGES OVER TO SNOW. MUCH OF THE SNOW PACK
IS GONE AND THE GROUND IS UNFROZEN...SW WE THINK THE POTENTIAL FOR
WIDESPREAD FLOODING IS MINIMAL BUT WITHIN BANK RIVER RISES ARE
EXPECTED.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...WIND ADVISORY FROM 10 AM THIS MORNING TO 10 PM EST THIS EVENING
     FOR MIZ052-058-059-064>067-071>074.

     WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 4 PM EST
     TUESDAY FOR MIZ037>040-043>046-050-051-056-057.

LM...SMALL CRAFT ADVISORY FROM 10 AM THIS MORNING TO 7 AM EST
TUESDAY
     FOR LMZ849.

     GALE WARNING FROM 10 AM THIS MORNING TO 7 AM EST TUESDAY FOR
     LMZ844>848.

&&

$$

SYNOPSIS...NJJ
SHORT TERM...NJJ
LONG TERM...MEADE
AVIATION...MEADE
HYDROLOGY...93
MARINE...93




USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.