Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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000
FXUS63 KGRR 241756
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
156 PM EDT TUE MAR 24 2015

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 330 AM EDT TUE MAR 24 2015

HIGH PRESSURE OVER THE REGION WILL BRING A GOOD DEAL OF SUNSHINE AND
SOME MILDER TEMPERATURES TO THE AREA COMPARED TO MONDAY. CLOUDS WILL
BE ON THE INCREASE THIS EVENING WITH PRECIPITATION DEVELOPING TOWARD
MIDNIGHT AND OVERNIGHT. THIS PRECIPITATION WILL START OFF AS SOME
RAIN DOWN SOUTH...WITH SOME FREEZING RAIN POSSIBLE FOR AREAS ALONG
AND NORTH OF I-96. FREEZING RAIN WILL NOT LAST LONG AS TEMPERATURES
WARM QUICKLY ABOVE FREEZING BY DAYBREAK ON WEDNESDAY. COLDER AIR
WILL FILTER INTO THE AREA ON THURSDAY AND HOLD ON THROUGH SATURDAY.

&&

.UPDATE...
ISSUED AT 1112 AM EDT TUE MAR 24 2015

WE PLAN TO ISSUE A WINTER WEATHER ADVIOSRY FOR FREEZING RAIN FROM
MIDNIGHT THROUGH 9 AM GENERALLY NORTH OF A MUSKEGON TO GREENVILLE
LINE. WE WILL BE COORDINATING WITH DETROIT EARLY THIS AFTERNOON
TO NAIL DOWN THE EXACT COUNTIES TO INCLUDE.

AFTER WATCHING THIS SYSTEM FOR OVER A WEEK NOW... AND GIVEN HOW
DRY THE AIR IS OVER US...IT TOTALLY MAKES SENSE TO ME THAT FROM
I-96 NORTH THE AIR WILL BE COLD ENOUGH FOR FREEZING RAIN TONIGHT.
PRECPITATION SHOULD REACH THE GRR AREA BY 2 AM AND THE REST OF
THE CWA BY 4 AM. IN THE I-96 AREA THE FREEZING RAIN WILL BE BRIEF...
NOT MORE THAN AN HOUR OR SO. JUST NORTH OF KENT COUNTY I COULD
SEE TEMPERATURES STAYING BELOW FREEZING THROUGH SUNRISE. GIVEN THE
TWO TO FOUR TENTHS OF AN INCH OR RAIN EXPECTED TO FALL IN THE 2 AM
TO 8 AM TIME FRAME OVER OUR NORTHERN COUNTIES...IT SEEMS THIS
WOULD RESULT IN SOME SIGNIFCANT TRAVEL ISSUES WITH THE WEDNESDAY
MORNING COMMUTE.

&&

.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 330 AM EDT TUE MAR 24 2015

OUR MAIN FCST CONCERN IN THE SHORT TERM IS FOR TONIGHT WITH THE
THREAT OF SOME FREEZING RAIN AT THE ONSET OF THE PCPN. WE WILL NOT
ISSUE AN ADVISORY FOR THIS YET AFTER COLLABORATING WITH SURROUNDING
OFFICES...BUT ONE COULD STILL BE NEEDED.

NO CONCERNS WITH THE FCST TODAY AS MOST OF THE AREA SHOULD SEE
MOSTLY SUNNY SKIES THROUGH THE DAY. A FAIRLY STRONG SHORT WAVE RIDGE
TO OUR WEST AND SFC RIDGING OVERHEAD WILL CONTROL OUR WEATHER. THE
SUNSHINE AND WARM AIR ADVECTION ALOFT WILL HELP TEMPS RECOVER A BIT
COMPARED TO YESTERDAY.

WE ARE THINKING THAT AREAS SOUTH OF I-96 WILL SEE MAINLY RAIN AT THE
ONSET OF PCPN TONIGHT. AREAS ALONG AND NORTH OF I-96 COULD SEE A
SHORT WINDOW OF SOME FREEZING RAIN BEFORE CHANGING OVER TO ALL RAIN
BY DAYBREAK ON WED. THE BEST THREAT FOR PCPN WILL BEGIN TOWARD 06Z
TONIGHT AS STRONG MOISTURE TRANSPORT NOSES UP INTO THE AREA VIA A 50
KNOT LLJ.

AS THE PCPN BEGINS...AREAS ALONG AND NORTH OF I-96 LOOK TO
STILL BE BELOW FREEZING AT THE SFC WHILE TEMPS ALOFT WILL BE WELL
ABOVE FREEZING. ANY FREEZING RAIN THAT DOES OCCUR WILL BE BRIEF /1-3
HRS...LONGEST NORTH/ WITH THE STRONG SRLY FLOW MOVING IN AND NO
COLDER AIR FEEDING IN FROM THE NORTH. RAIN WILL THEN TAPER OFF WED
MORNING AFTER 12Z WHEN THE LLJ AND BEST MOISTURE TRANSPORT SHIFTS
EAST OF THE AREA. WE ARE STILL LOOKING FOR SOME BREEZY CONDITIONS ON
WED IN THE DRY SLOT. FCST SOUNDINGS INDICATE THAT WE WILL LIKELY MIX
WINDS OF AROUND 30-35 KNOTS DOWN. THIS WOULD BE A LITTLE BELOW WIND
ADVISORY CRITERIA.

WE ARE NOT AS CONCERNED ABOUT THE SECONDARY WAVE THAT WILL RIDE NE
ALONG THE FRONT THAT WILL BE SE OF THE AREA FOR WED NIGHT AND EARLY
THU. THERE IS GOOD MODEL CONSENSUS THAT THE FRONT WILL BE FAR ENOUGH
SE THAT THE MAJORITY OF PCPN WITH IT WOULD ALSO REMAIN SE OF THE
AREA. THERE IS STILL A CHC THAT SOME OF IT COULD SNEAK UP INTO OUR
FAR SE COUNTIES...SO WE HAVE A CHC OF PCPN REMAINING FOR THAT AREA.
SOME COLDER AIR WILL HAVE FILTERED IN BY THEN...SO THERE COULD BE A
MIXTURE OF RAIN AND/OR SNOW.

.LONG TERM...(THURSDAY NIGHT THROUGH MONDAY)
ISSUED AT 330 AM EDT TUE MAR 24 2015

MAIN STORY LINE IN THE LONG TERM IS THE COLD. TEMPERATURES FROM
THURSDAY NIGHT INTO SATURDAY WILL BE BELOW NORMAL. HIGHS ON FRIDAY
COULD BE 20 DEGREES BELOW NORMAL FOR THE DATE.

COLD AIR WILL POUR INTO THE GREAT LAKES REGION BEHIND THE MID WEEK
SYSTEM. IT WILL BE FLOWING IN THURSDAY NIGHT WITH THE CORE OF THE
COLD AIR (-15C TO -20C AIR AT 850MB/S) IN PLACE FRIDAY AND FRIDAY
NIGHT.

WE WILL LIKELY SEE SNOW SHOWERS ASSOCIATED WITH THE UPPER TROUGH
THURSDAY NIGHT INTO FRIDAY AS WELL AS SOME LAKE EFFECT GIVEN DELTA
T/S CLIMBING INTO THE MIDDLE TO UPPER TEENS C. NOT EXPECTING MUCH IN
THE WAY OF ACCUMULATIONS...BUT SOME LIGHT ACCUMS A DISTINCT
POSSIBILITY TOWARDS LAKE MICHIGAN ESPECIALLY. MOST LIKELY AN INCH OR
LESS.

HIGH PRESSURE SHOULD KEEP THE AREA MAINLY DRY FROM FRIDAY NIGHT
THROUGH SATURDAY NIGHT.

PRECIPITATION WILL SPREAD BACK IN SUNDAY AND SUNDAY NIGHT WITH THE
GFS AND ECMWF AT ODDS WITH ONE ANOTHER LEADING TO A LOWER CONFIDENCE
FORECAST. THE GFS IS NOW THE DEEPER MODEL WITH THIS SYSTEM WHICH IS
A FLIP FROM LAST NIGHT. IT IS A SHORTWAVE IN NORTHWEST FLOW. THE GFS
IS COLDER AND DEEPER AND WOULD RESULT IN MORE IN THE WAY SNOW.
STAYING THE COURSE AT THIS POINT WITH RAIN/SNOW IN THE FORECAST. THE
SYSTEM SWEEPS EAST SUNDAY NIGHT WITH DRY WEATHER FORECAST FOR
MONDAY.

TEMPERATURES SUNDAY AND MONDAY NUDGE BACK TOWARDS NORMAL AFTER COLD
DAYS ON FRIDAY AND SATURDAY. STILL...ONLY EXPECTING 40S BOTH
DAYS...SO NO SPRING WARMTH IN THE LONG TERM.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 156 PM EDT TUE MAR 24 2015

VFR CONDITIONS WILL PERSIST AT ALL TAF SITES THROUGH 06Z.
CONDITIONS WILL THEN DETERIORATE FROM SOUTHWEST TO NORTHEAST AS AN
AREA OF RAIN MOVES THROUGH LOWER MI. SURFACE TEMPS AT THE NORTHERN
TAF SITES ARE EXPECTED TO BE HOVERING SLIGHTLY BELOW FREEZING AS
THE PRECIPITATION MOVES IN FROM 06Z TO 07Z. KMKG AND KGRR COULD
SEE AN HOUR OR TWO OF FREEZING RAIN AT THE ONSET OF THE RAINFALL.
WITH SUCH DRY AIR IN PLACE WITH EASTERLY LOW LEVEL
FLOW...CONCERNED THE SURFACE TEMP WILL WET BULB DOWN A
BIT...RESULTING IN THE FZRA AT KMKG AND KGRR.

JUST RAIN EXPECTED AT ALL TAF SITES AFTER 08Z WITH WINDS RAMPING
UP OUT OF THE SOUTH. IFR CONDITIONS WILL BECOME WIDESPREAD AFTER
08Z WITH THE WIDESPREAD RAINS. VCTS IS NOT OUT OF THE QUESTION FOR
THE SOUTHERN TAF SITES...ESPECIALLY IN THE 07Z TO 10Z
TIMEFRAME...BUT CONFIDENCE WAS TOO LOW TO INCLUDE IN THE TAFS. WINDS
WILL BE AN ISSUE FOR THE REST OF THE FORECAST PERIOD AFTER 06Z AS
THE PRECIP SHIELD MOVES IN. ESE WINDS GUSTING TO 25 KTS WILL VEER
SOUTHERLY TOWARD 10Z AND EVENTUALLY SOUTHWESTERLY TOWARD 15Z
WEDNESDAY STILL GUSTING TO 25 KTS. OCCASIONAL GUSTS TO 30 KTS ARE
POSSIBLE. RAINFALL IS EXPECTED TO MOVE OFF TO THE EAST AFTER 15Z
WEDNESDAY.

&&

.HYDROLOGY...
ISSUED AT 1238 PM EDT TUE MAR 24 2015

RIVER LEVELS WILL CONTINUE TO FALL THROUGH WEDNESDAY. THE GROUND
HAS THAWED AND SOILS ARE DRYING OUT. A RAIN AND FREEZING RAIN
EVENT TONIGHT INTO EARLY WEDNESDAY IS EXPECTED TO HAVE
PRECIPITATION TOTALS OF AROUND A HALF INCH. LOCALLY HIGHER
AMOUNTS ARE POSSIBLE... IF THUNDERSTORMS OCCUR. THIS MAY CAUSE
RIVER LEVELS TO LEVEL OFF OR EVEN CREEP BACK UP TO NEAR BANK
FULL... BUT FLOODING IS NOT A HIGH PROBABILITY.

&&

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

$$

UPDATE...WDM
SYNOPSIS...NJJ
SHORT TERM...NJJ
LONG TERM...DUKE
AVIATION...EBW
HYDROLOGY...63






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