Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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120
FXUS63 KGRR 041759
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1259 PM EST THU FEB 4 2016

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 325 AM EST THU FEB 4 2016

TEMPERATURES WILL AVERAGE NEAR TO SLIGHTLY ABOVE NORMAL THROUGH
THE REST OF THE WEEK AND WEEKEND WITH A FEW LIGHT SNOW SHOWERS
AND FLURRIES. THERE IS POTENTIAL FOR A STRONGER CLIPPER SYSTEM TO
BRING MORE WIDESPREAD SNOW SUNDAY INTO MONDAY. MUCH COLDER WEATHER
IS ANTICIPATED FOR MOST OF NEXT WEEK.

&&

.UPDATE...
ISSUED AT 714 AM EST THU FEB 4 2016

I UPDATED THE FORECAST GRIDS TO HAVE THE SNOW SHOWERS EXTEND
FARTHER INLAND AND LAST LONGER INTO THE AFTERNOON. THERE CURRENTLY
IS A SHORTWAVE SEEN ON THE WATER VAPOR IMAGE LOOPS HEADING TOWARD
CHI. IR SATELLITE LOOPS SHOW COOLING CLOUD TOPS OVER EASTERN
WISCONSIN AND OVER LAKE MICHIGAN AND OUR RADAR MOSAIC USING THE
MRM DATA SHOWS A SECOND AREA OF SNOW SHOWERS OVER WESTERN LAKE
MICHIGAN HEADING TOWARD WESTERN LOWER MICHIGAN. THE RAP...
HRRR...NAM4KM ALL SUGGEST SNOW SHOWERS WILL LAST INTO EARLY
AFTERNOON AND EXTEND WELL INLAND. MODEL SOUNDING SHOW THE DGZ IS
WELL WITHIN THE CLOUD DECK SO IT SHOULD NOT BE ALL THAT HARD TO
GET SNOW SHOWERS TODAY. SO BASED ON ALL OF THIS I INCREASED THE
POP AND INCREASED SNOWFALL AMOUNTS TO BETWEEN A HALF INCH AND AN
INCH FOR TODAY.

&&

.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 325 AM EST THU FEB 4 2016

LIGHT SNOW SHOWERS AND FLURRIES WILL LINGER THIS MORNING AIDED BY
ANOTHER SHORTWAVE THAT WILL PUT MAINLY OUR FAR SOUTHERN FCST AREA
IN AN AREA OF STRONGER PVA THIS MORNING THAT WILL ENHANCE LIGHT
SNOW SHOWERS. THE PCPN WILL TAPER OFF THIS AFTERNOON IN SUBSIDENCE
UNDER THE HIGH PRESSURE RIDGE WHICH WILL BUILD IN.

DRY WX WILL CONTINUE THROUGH THE EVENING BEFORE A TROUGH OF LOW
PRESSURE BRINGS MORE LIGHT SNOW SHOWERS AND FLURRIES LATE TONIGHT
INTO EARLY FRIDAY. THE FLOW WILL BECOME ANTICYCLONIC AND RESULT IN
DRY WEATHER FOR FRIDAY AFTERNOON AND EVENING.

ANOTHER LOW PRESSURE SYSTEM TRACKING ACROSS THE NORTHERN GREAT
LAKES REGION WILL CAUSE LIGHT SNOW SHOWERS TO REDEVELOP MAINLY
OVER OUR FAR NW FCST AREA LATE FRIDAY NIGHT AND THEN ACROSS OUR
NORTHERN FCST AREA NORTH OF I-96 SATURDAY. ANY SNOW ACCUMULATIONS
THROUGH THE SHORT TERM FCST PERIOD WOULD BE VERY LIGHT AT
GENERALLY UNDER AN INCH.

.LONG TERM...(SATURDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 325 AM EST THU FEB 4 2016

OVERALL IT WOULD SEEM TO ME THE TREND OVERALL IS TOWARD COLDER
TEMPERATURE. THE COLDEST TEMPERATURES WILL BE THE MIDDLE OF NEXT
WEEK IN THE WEDNESDAY/THURSDAY TIME FRAME. TEMPERATURES SHOULD STAY
IN THE 20S IN THE AFTERNOON BY THEN. THE PATTERN FAVORS MOSTLY LAKE
ENHANCED SNOWFALL. IF YOU LIVE NEAR OR WEST OF US-131 PLAN ON SNOW
MOST OF THE TIME STARTING SUNDAY NIGHT. IF YOUR EAST OF THERE PLAN
ON PARTLY CLOUDY SKIES WITH FLURRIES FOR THE MOST PART.

THERE IS BETTER AGREEMENT BETWEEN THE GFS AND ECMWF FOR NEXT WEEK
BUT I STILL HAVE QUESTION ABOUT THIS. THE QUESTION IN MY MIND IS
DOES THE MJO WARM PHASE WIN THE DAY OR DOES THE STRATOSPHERE WARMING
EVENT TAKE THE DAY (WILL IT BE COLDER OR WARMER THAN NORMAL NEXT
WEEK)?

ON THE ONE HAND WE HAVE AN MJO IN PHASE 4...WARM FOR THE GREAT
LAKES...FAVORING RIDGING OVER THE EASTERN UNITED STATES. MEANWHILE
WE HAVE A VERY IMPRESSIVE STRATOSPHERIC WARMING EVENT OVER RUSSIANTHAT
MOVES INTO WESTERN NORTH AMERICA EARLY NEXT WEEK. THIS IS ONE THE
OF THE STRONGEST EVENTS I HAVE SEEN THIS YEAR. MAYBE STRONGER THAN
ANYTHING THAT HAPPENED LAST WINTER ACTUALLY. THESE EVENTS SPLIT
THE POLAR VORTEX INTO TWO PARTS AND THE MODELS ALL SHOW THIS
STARTING TO HAPPEN BY THE MIDDLE OF NEXT WEEK. CURRENTLY THE
CENTER OF THE POLAR VORTEX IS NORTH OF GREENLAND. BY THURSDAY WE
SEE BOTH THE ECMWF AND GFS AND THERE ENSEMBLES SHOWING IT MOVING
SOUTHWEST TO NORTHERN HUDSON BAY. WHILE THIS IS GOING ON THERE ARE
TWO STRONG EAST ASIAN JETS THAT HEAD ACROSS THE DATELINE. THE
FIRST ONE IS CURRENTLY NEAR THE DATELINE AND IT SEEMS TO HELP
STRENGTHEN A STORM IN THE GULF OF ALASKA AND DOES NOT DO WHAT
WOULD BE TYPICAL...HEAD EAST TO THE WEST COAST OF THE UNITED
STATES. THAT IN TURN HELPS BUILD THE WESTERN RIDGE WHICH HELPS
SEND NORTHERN STREAM WAVES FARTHER SOUTH INTO THE NORTHERN UNITED
STATES. THIS IS WHAT BRINGS THAT SYSTEM INTO OUR AREA ON MONDAY.
THEN THROUGH THERE IS A SECOND 180 TO 200 KNOT EAST ASIAN JET
THAT HEADS INTO THE BACK SIDE OF THAT GULF OF ALASKA SYSTEM. THAT
HELPS DEEPEN THE TROUGH EVEN FARTHER AND BUILDS THE WESTERN RIDGE
EVEN MORE. SO BY THE MIDDLE OF NEXT WEEK WE HAVE A RATHER DEEP
EASTERN TROUGH. THE ECWMF SHOWS THE AO GOING SIGNIFICANTLY
NEGATIVE BY THE MIDDLE OF NEXT WEEK (FROM THE 03/12Z RUN). THE GFS
HAS IT GETTING AS NEGATIVE AS IT DID DURING THE COLDEST WEATHER WE
HAD LAST MONTH. ALL OF THIS SEEMS TO SUGGEST COLDER WEATHER WILL
PREVAIL. ALSO IT WOULD KEEP ANY SOUTHERN STREAM SYSTEMS FROM
IMPACTING OUR WEATHER. ANY PRECIPITATION WOULD BE FROM CLIPPER
SYSTEMS AND OR LAKE EFFECT SNOW.

WE HAVE ONE CLIPPER SYSTEM THAT PASSES NORTH OF LAKE SUPERIOR FRIDAY
NIGHT. BEHIND THAT IS THE NEXT CLIPPER SYSTEM. THAT ONE IS THE ONE
THAT DIVES MUCH FARTHER SOUTH... TO WESTERN LAKE SUPERIOR BY SUNDAY
EVENING. ALL OF THE MODELS SHOW THIS SYSTEM CONTINUING TO DIG
SOUTHEAST BEING OVER LAKE ERIE BY TUESDAY. THIS IS ALL RELATED TO
THAT BUILDING WESTERN RIDGE.  ALL MODELS CLOSE OFF A 500 MB LOW OVER
OVER CENTRAL LAKE MICHIGAN BY MONDAY AFTERNOON. THAT SYSTEM IS OVER
CENTRAL OHIO BY TUESDAY. CLEARLY THIS WOULD BRING LAKE ENHANCED
SNOW TO THE AREA MONDAY INTO TUESDAY. BEYOND THAT THE TRULY ARCTIC
AIR COMES IN AND THAT WOULD RESULT IN C0NTINUED LAKE EFFECT INTO
AT LEAST THURSDAY.

SO...IF THE MJO WERE TO PREVAIL... THAT MONDAY SYSTEM WOULD STAY
FARTHER NORTH AND WE WOULD NOT GET INTO THE COLD AIR DURING THE
MIDDLE OF NEXT WEEK. GIVEN HOW THE MODELS KEEP TRENDING TOWARD
COLDER I WILL LEAN THAT WAY FOR NOW AND CALL IT GOOD.


&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1253 PM EST THU FEB 4 2016

LIGHT LAKE EFFECT SNOW SHOWERS WILL CONTINUE THROUGH TONIGHT AND
WILL DIMINISH FRIDAY MORNING WHEN DRIER AIR MOVES IN. LOOK FOR
MOSTLY MVFR THROUGH THE PERIOD.

&&

.MARINE...
ISSUED AT 325 AM EST THU FEB 4 2016

NW WINDS OF AROUND 10 TO 15 KTS WILL BACK TO THE WEST THEN SW
TODAY AND CONTINUE TO GRADUALLY DIMINISH. WAVE HEIGHTS WILL
GRADUALLY SUBSIDE THROUGH THE DAY AS WELL.


&&

.HYDROLOGY...
ISSUED AT 258 PM EST WED FEB 3 2016

MINOR FLOODING IS POSSIBLE THIS WEEK... ESPECIALLY IN LOWLAND AREAS
NEAR RIVERS. SOME RIVERS MAY EXCEED BANKFULL DUE TO SNOW MELT AND
PRECIPITATION FROM THE LAST STORM. TOTAL PRECIPITATION OF ONE TO
AROUND ONE AND A HALF INCHES FELL. RIVER FLOOD ADVISORIES HAVE BEEN
ISSUED FOR SYCAMORE CREEK AT HOLT... FLAT RIVER AT SMYRNA... ROGUE
RIVER AT ROCKFORD... MAPLE RIVER AT MAPLE RAPIDS AND GRAND RIVER AT
IONIA.

&&

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

$$

UPDATE...WDM
SYNOPSIS...LAURENS
SHORT TERM...LAURENS
LONG TERM...WDM
AVIATION...04
HYDROLOGY...63
MARINE...LAURENS



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