Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 301930
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
330 PM EDT MON MAR 30 2015

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

.SYNOPSIS...
ISSUED AT 330 PM EDT MON MAR 30 2015

A CLIPPER TYPE SYSTEM WILL SLIDE THROUGH THE GREAT LAKES REGION
TONIGHT INTO TUESDAY MORNING. RAIN AND SNOW WILL OCCUR TONIGHT WITH
THE SNOW MOST PREVALENT NORTH OF INTERSTATE 96 TOWARDS CENTRAL LOWER
MICHIGAN. SEVERAL INCHES OF SNOW ARE POSSIBLE TONIGHT IN A NARROW
BAND ACROSS CENTER LOWER MICHIGAN. THE PRECIPITATION WILL COME TO AN
END TUESDAY MORNING WITH DRY CONDITIONS EXPECTED FROM MIDDAY TUESDAY
INTO WEDNESDAY NIGHT. THE NEXT SYSTEM TO AFFECT THE AREA WILL MOVE
IN LATE WEDNESDAY NIGHT BRINGING RAIN INTO THURSDAY. TEMPERATURES
WILL WARM INTO MID WEEK WITH READINGS RISING INTO THE 50S AND 60S ON
THURSDAY.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT)
ISSUED AT 330 PM EDT MON MAR 30 2015

MAIN ITEM IN THE SHORT TERM IS THE PRECIPITATION EVENT TONIGHT. A
CLIPPER SYSTEM WILL PUSH PLAIN RAIN INTO THE AREA AFTER 700PM WHICH
WILL LIKELY CONTINUE THROUGH MIDNIGHT. AS THE BOUNDARY LAYER COOLS
OVERNIGHT WE ARE EXPECTING SNOW TO MIX IN AND EVEN COMPLETELY CHANGE
OVER ACROSS PORTIONS OF CENTRAL LOWER MI. THERE IS STRONG FGEN
FORCING NOTED IN THE 900-800MB LAYER AS WELL AS STRONG ISENTROPIC
LIFT ON THE 290K SURFACE. BOTTOM LINE...THINKING THE PRECIPITATION
IS GOING TO HAVE A CONVECTIVE ELEMENT TOO IT WHICH WILL LIKELY LEAD
TO A NARROW SWATH OF ACCUMULATING SNOW. AT THIS POINT THINKING THE
HEAVIER BAND OF SNOW IS GOING TO EXTEND FROM THE PENTWATER AREA
SOUTHEAST THROUGH NEWAYGO TOWARDS ALMA. HAVE A 1-3 INCH SWATH IN THE
FORECAST IN THESE AREAS. IF THE CHANGEOVER OCCURS A BIT QUICKER AND
THE CONVECTIVE ELEMENTS ROLL OVER THE SAME AREAS AN ISOLATED 4 INCH
AMOUNT NOT OUT OF THE REALM OF POSSIBILITIES. FOR I-96 ON SOUTH
THINKING THIS IS A RAIN EVENT. A TOUCH OF LIGHT SNOW IS POSSIBLE ON
THE TAIL END TOWARDS 12Z BEFORE THE PRECIPITATION SHUTS OFF ALONG
I-96...BUT THIS SHOULD NOT BE AN ISSUE. EXPECTING A DRY LATE MORNING
AND AFTERNOON ON TUESDAY.

OTHERWISE...SKIES WILL GRADUALLY BECOME PARTLY CLOUDY IN THE WAKE OF
THE CLIPPER TUESDAY AFTERNOON AND NIGHT. WEDNESDAY SHOULD BE A QUIET
DAY AS HIGH PRESSURE DRIFTS EAST. THE NEXT SYSTEM ALREADY TAKES AIM
FOR WEDNESDAY NIGHT WITH DECENT 850MB MOISTURE TRANSPORT SITUATED
ACROSS THE CWA AFTER 06Z. HAVE SCATTERED POPS IN THE FORECAST AT
THIS POINT...BUT THEY MAY NEED TO BE RAISED WITH TIME.



.LONG TERM...(THURSDAY THROUGH MONDAY)
ISSUED AT 330 PM EDT MON MAR 30 2015

THE LONG TERM PORTION OF THE FCST CAN BE SUMMARIZED BY BEING
UNSETTLED WITH UP AND DOWN TEMPERATURES.

THE MAIN FEATURE WILL BE THE FRONTAL SYSTEM THAT WILL PUSH THROUGH
THE AREA ON THU. THE MODELS HAVE COME INTO DECENT AGREEMENT WITH
ALLOWING TEMPS TO WARM INTO THE 60S FOR MUCH OF THE AREA BEFORE RAIN
WOULD MOVE IN BY THU AFTERNOON. WE HAVE MENTIONED A CHC OF THUNDER
AS THERE WILL BE SUFFICIENT ELEVATED INSTABILITY PRESENT FOR THE
THREAT. THE AGREEMENT COMES WITH THE NRN STREAM WAVE BEING A LITTLE
BIT MORE AMPLIFIED THAN THE GFS YESTERDAY...BUT NOT AS AMPLIFIED AS
THE EURO WAS.

WE HAVE ADDED A CHC OF RAIN BACK INTO THE FCST FOR THE SE PORTION OF
THE CWFA ON FRI. THE SRN STREAM SYSTEM DIGGING INTO THE ROCKIES WILL
LIFT OUT A BIT LATER NOW AND RIDE UP ALONG THE FRONT THAT WILL BE
JUST SE OF THE AREA. THERE IS ENOUGH OF A CHC THAT WE WILL BE ON THE
NW EDGE OF THE PCPN.

WE WILL SEE THE NEXT CHC OF PCPN COME IN DURING THE DAY ON SAT. WE
WILL SEE ANOTHER SHORT WAVE COME IN FROM THE NW AFTER THE WAVE FROM
THE SW EXITS THE AREA. THIS COULD BE RAIN OR RAIN/SNOW AT THE ONSET.
AS COLDER AIR MOVES IN...THE BACK EDGE OF THE PCPN WILL LIKELY
CHANGE OVER TO SNOW BEFORE ENDING.

RIDGING WILL BUILD IN FOR SUN AND BRING A DRY DAY. THE SAT FRONT
WILL THEN DRIVE BACK NORTH AS A WARM FRONT ON MON AS THE UPPER
TROUGH MOVES OUT AND RIDGING BUILDS BACK IN. THE MOISTURE RETURN
WITH THE FRONT WILL BRING YET ANOTHER CHANCE OF MAINLY RAIN TO THE
AREA.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 149 PM EDT MON MAR 30 2015

THE MAIN FOCUS OF THE 18Z FCSTS IS THE SYSTEM DROPPING SE THROUGH
THE AREA TONIGHT. VFR CONDITIONS ARE EXPECTED INTO THIS EVENING
WITH ONLY HIGH CLOUDS EXPECTED THROUGH AT LEAST 00Z. WIND GUSTS OF
20-30 KNOTS THIS AFTERNOON WILL DIMINISH TOWARD 21-23Z.

WE EXPECT PCPN TO START TO SLIP INTO KAZO AROUND 01Z...AND THEN
SPREAD THROUGH THE REMAINDER OF THE SITES THROUGH ABOUT 03-04Z. WE
EXPECT THE TERMINALS ALL TO BE MAINLY RAIN THROUGH MOST OF THE
EVENT THAT WILL LAST UNTIL ABOUT 12Z OR SO ON TUE. PCPN COULD
CHANGE OVER TO KLAN FOR THE LAST HOUR OR TWO AS THE COLDER AIR
REACHES THERE FIRST COMING IN FROM THE NE.

CONDITIONS WILL START OUT AT VFR AT ALL SITES AS THE PCPN BEGINS.
WE THEN EXPECT IT TO GO TO MVFR AND POSSIBLY IFR AT THE NRN SITES
JUST N OF THE SFC LOW. THE SRN SITES WILL REMAIN VFR MOST OF THE
NIGHT UNTIL THE END OF THE EVENT WHEN THE FRONT MOVES SOUTH. THEN
SOME MVFR WILL BE POSSIBLE THERE. CIGS WILL GRADUALLY IMPROVE
TOWARD THE END OF THIS FCST PERIOD.

&&

.MARINE...
ISSUED AT 330 PM EDT MON MAR 30 2015

LIGHTER WINDS SHOULD KEEP WAVES IN CHECK THROUGH WEDNESDAY MID
AFTERNOON. IN GENERAL...A WEAK PRESSURE GRADIENT IS IN PLACE THROUGH
THAT TIME WITH HIGH PRESSURE OVERHEAD TUESDAY NIGHT INTO WEDNESDAY
MORNING. SOUTHERLY WINDS WILL RAMP UP SIGNIFICANTLY AS WE HEAD FROM
WEDNESDAY AFTERNOON INTO WEDNESDAY NIGHT. WAVES OF 2 FEET OR LESS
FOR THE MOST PART THROUGH WEDNESDAY WILL BUILD TO 3 TO 6 FEET
WEDNESDAY EVENING. MARINE HEADLINES WILL LIKELY BE NEEED FOR
WEDNESDAY NIGHT.

&&

.HYDROLOGY...
ISSUED AT 330 PM EDT MON MAR 30 2015

A FEW RIVERS HAD MINOR UPTICKS IN LEVELS FROM THE PRECIPITATION ON
SUNDAY. RIVERS ARE RUNNING NEAR TO BELOW NORMAL FOR THE TIME OF
YEAR. NO HEAVY PRECIPITATION IS EXPECTED WITH THE UPCOMING SYSTEM
TONIGHT... SO RIVERS WILL REMAIN COMFORTABLY BELOW BANKFULL.

&&

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

$$

SYNOPSIS...DUKE
SHORT TERM...DUKE
LONG TERM...NJJ
AVIATION...NJJ
HYDROLOGY...CAS
MARINE...DUKE









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