Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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000
FXUS63 KGRR 131741
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
141 PM EDT SAT SEP 13 2014

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 318 AM EDT SAT SEP 13 2014

SHOWERS WILL END TODAY AS LOW PRESSURE MOVES AWAY. SKIES WILL
CLEAR TONIGHT AND SOME FROST IS EXPECTED NORTH OF INTERSTATE 96.
FAIR WEATHER IS EXPECTED SUNDAY THEN A COLD FRONT WILL BRING SOME
LIGHT RAIN FOR MONDAY.

&&

.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 318 AM EDT SAT SEP 13 2014

THE STEADY RAIN WILL BE EXITING TO THE EAST THIS MORNING BUT LAKE
EFFECT SHOWERS WILL PERSIST THIS MORNING BEFORE HEIGHT RISES
BRING ENOUGH SUBSIDENCE TO SUPPRESS THEM. SFC HIGH BUILDS IN THIS
AFTERNOON WITH CLEARING EXPECTED BY EVENING. WE STILL EXPECT
PATCHY FROST NORTH OF INTERSTATE 96 BY SUNDAY MORNING WITH
TEMPERATURES DROPPING TO FREEZING IN SOME OF THE COLD HOLLOWS.

SFC HIGH MOVES EAST SUNDAY WITH A COLD FRONT SAGGING INTO NORTHERN
LOWER MICHIGAN SUNDAY NIGHT AS FLAT UPPER TROUGHING ARRIVES. SOME
SHOWERS ALONG THE FRONT WILL AFFECT THE NORTHWEST ZONES BY LATE
SUNDAY NIGHT...BUT THE BULK OF THE SHOWERS WILL MOVE THROUGH ON
MONDAY WITH THE SFC FROPA AND UPPER SHORTWAVE TROUGH AXIS MOVING
THROUGH.

.LONG TERM...(MONDAY NIGHT THROUGH FRIDAY)
ISSUED AT 318 AM EDT SAT SEP 13 2014

EXCEPT FOR A RESIDUAL THREAT OF RAIN THE FIRST PART OF MON NIGHT
RIGHT AT THE BEGINNING OF THE LONG TERM...IT LOOKS LIKE WE WILL SEE
A FAIRLY QUIET AND MILD PERIOD IN GENERAL. THIS WILL BE A CHANGE
FROM THE WET AND UNSETTLED PATTERN WE HAVE BEEN IN FOR THE LAST
COUPLE OF WEEKS.

THE CHANCE OF RAIN MON EVENING WILL BE RATHER SMALL...AND THE THREAT
SHOULD END BY THE SECOND HALF OF MON NIGHT. THE COLD FRONT WILL BE
SOUTH OF THE AREA BY THE BEGINNING OF THE LONG TERM. WE WILL SEE THE
UPPER SHORT WAVE PASS THROUGH THE AREA BY 06Z TUE...WHICH WILL KEEP
A LOW THREAT OF A FEW LIGHT RAIN SHOWERS IN UNTIL ITS PASSAGE.

THE REMAINDER OF THE WEEK THEN LOOKS TO BE RATHER QUIET AND MILD.
THE UPPER JET WILL REMAIN NORTH OF THE AREA THROUGH THE PERIOD WITH
A NW FLOW IN PLACE OVER THE STATE. THIS WILL KEEP SHORT WAVES OUT OF
THE AREA AND THE COOL AIR FROM THIS WEEK UP IN CANADA. A FAIRLY
STRONG SHORT WAVE DOES TRY TO DIG FURTHER SOUTH TOWARD THE AREA IN
THE THU TIME FRAME. THIS WILL PUSH A MOISTURE-STARVED COLD FRONT
INTO THE AREA. PCPN DOES NOT LOOK LIKELY AT THIS TIME WITH IT. IT
DOES LOOK LIKE THAT IT WILL STOP THE MODERATING TREND THAT IS
ONGOING DURING THE FIRST HALF OF THE WEEK.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 141 PM EDT SAT SEP 13 2014

THE PRIMARY QUESTION IS WILL THE CLOUDS CLEAR BY EVENING?
CURRENTLY VFR CIGS PREVAIL ACROSS OUR TAF SITES AT 17Z. CLOUDS
ARE MOSTLY OPEN CELL CU.  MODEL SOUNDING SUGGEST THE CLOUDS SHOULD
SLOWLY MIX OUT BY 21Z OR SO. THE OUTGOING RADIATION FROM THE HRRR
MODEL (WHICH IS DOING A GREAT JOB OF SHOWING WHERE THE CLOUDS ARE
NOW) SUGGESTS THE CLOUDS CLEAR OUT BY 00Z. SO I WENT ALONG WITH
THE IDEA OF CLEARING THE CLOUD OUT IN OUR 18Z TAFS BY 21Z.

THE NEXT ISSUE IS AS WINDS TURN TO THE SOUTH EARLY SUNDAY MORNING
DO LOW CLOUDS REDEVELOP OVER LAKE MICHIGAN AND SPREAD INLAND BY MID
MORNING SUNDAY? GIVEN HOW COLD THIS AIR IS AN THAT LAKE MICHIGAN
SURFACE TEMPERATURES ARE MOSTLY IN THE MID 60S (BASED ON THE SOUTH
BUOY) IT WOULD SEEM LIKELY THAT WILL HAPPEN. I BROUGHT CLOUDS BACK
INTO MKG BY 10Z. THEY MAY MOVE INTO THE GRR TAF SITE AFTER 12Z BUT
FOR NOW I DID NOT PUT THAT IN THE TAF.



&&

.MARINE...
ISSUED AT 1123 AM EDT SAT SEP 13 2014

DECIDED TO EXPAND THE SMALL CRAFT ADVISORY UP THE ENTIRE NEARSHORE
NORTH TO MANISTEE. NW WINDS WERE CREATING WAVES OF 3-4 FEET FORM
HOLLAND NORTH TO MANISTEE AND THERE SHOULD BE A SLIGHT UP TICK TO
THE WAVES WITH MORE DIURNAL MIXING. WAVES REMAIN AS HIGH AS 8 FEET
BETWEEN HOLLAND AND ST. JOE...SO THAT CONTINUES TO DO WELL.

AFTER AN UPTICK TO THE WINDS/WAVES THIS AFTERNOON...EXPECT A
FAIRLY QUICK DOWNWARD TREND BY THIS EVENING...SO HAVE THE HEADLINE
ENDING AT 10 PM.


&&

.HYDROLOGY...
ISSUED AT 318 AM EDT SAT SEP 13 2014

NO HYDRO ISSUES.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 10 PM EDT THIS EVENING FOR LMZ844>849.

&&

$$

SYNOPSIS...OSTUNO
SHORT TERM...OSTUNO
LONG TERM...NJJ
AVIATION...WDM
HYDROLOGY...OSTUNO
MARINE...JK






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