Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 120546
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
146 AM EDT FRI SEP 12 2014

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 305 PM EDT THU SEP 11 2014

COOL WEATHER WILL CONTINUE THROUGH SATURDAY. AN UPPER LEVEL
SYSTEM WILL BRING SOME SHOWERS LATE FRIDAY THROUGH FRIDAY NIGHT
INTO EARLY SATURDAY. SOME PATCHY FROST IS POSSIBLE NORTH OF
GRAND RAPIDS SATURDAY NIGHT. TEMPERATURES WILL MODERATE SLIGHTLY
TO CLOSER TO NORMAL EARLY NEXT WEEK.

&&

.UPDATE...
ISSUED AT 1118 PM EDT THU SEP 11 2014

PATCHY DRIZZLE PERSISTS ACROSS THE REGION. APX SOUNDING SHOWS THE
MOIST LOW LEVELS. FLOW IN THIS MOIST REGION REMAINS CONVERGENT FOR
A FEW MORE HOURS. AS A RESULT THE LIGHT PRECIPITATION WILL LINGER.
THE FORECAST HAS BEEN UPDATED TO REFLECT THIS.

UPDATE ISSUED AT 704 PM EDT THU SEP 11 2014

ADDED DRIZZLE TO THE EVENING FORECAST FOR MUCH OF THE REGION.
RADAR AND SURFACE OBSERVATIONS INDICATE THAT THERE IS SOME DRIZZLE
OUT THERE AS OF 23Z. SOME RETURNS NEAR CADILLAC WERE DROPPING
SOUTH PLUS LUDINGTON OBSERVATION SHOWED DRIZZLE. SO...FOR A FEW
HOURS...MUCH OF THE REGION COULD SEE SOME LIGHT PRECIPITATION.

&&

.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 305 PM EDT THU SEP 11 2014

UNSEASONABLY COOL CONDITIONS WILL CONTINUE TONIGHT WITH LOW TEMPS
RANGING FROM THE UPPER 30S NORTH TO NORTHEAST OF KGRR TO THE LOW TO
MID 40S FURTHER SOUTH. FAIRLY EXTENSIVE LOW CLOUD COVER WILL LINGER
TONIGHT DUE TO CYCLONIC FLOW COLD AIR ADVECTION AND LINGERING LOW
LEVEL MOISTURE AND LAKE EFFECT. POTENTIAL FOR ANY FROST UP NORTH
TONIGHT IS MITIGATED BY LINGERING LOW CLOUD COVER.

MAX TEMPS FRIDAY WILL ONLY REACH THE 55 TO 60 DEGREE RANGE. THE
STRONG UPPER LEVEL SHORTWAVE APPROACHING FROM THE WEST WILL BRING
POTENTIAL FOR A FEW SHOWERS AS EARLY AS FRIDAY AFTERNOON. THE
BETTER CHANCE FOR RAIN SHOWERS ACROSS OUR AREA WILL COME FRIDAY
EVENING THROUGH FRIDAY NIGHT INTO EARLY SATURDAY AS THE UPPER
LEVEL SYSTEM MOVES IN. NO FROST IS ANTICIPATED FRIDAY NIGHT DUE TO
EXTENSIVE CLOUD COVER THAT HOLD MIN TEMPS UP IN THE 40 TO 45
DEGREE RANGE.

HIGH PRESSURE WILL BUILD IN TO PRODUCE CLEARING SKIES SATURDAY
AFTERNOON AND CLEAR SKIES SATURDAY NIGHT. EXCELLENT RADIATIONAL
COOLING CONDITIONS ARE ANTICIPATED SATURDAY NIGHT DUE TO CLEAR SKIES
AND CALM WINDS THAT WILL ALLOW MIN TEMPS TO DROP INTO THE LOWER TO
MIDDLE 30S NORTH TO NORTHEAST OF KGRR WHERE PATCHY FROST IS LIKELY
TO DEVELOP OVERNIGHT.

.LONG TERM...(SUNDAY THROUGH THURSDAY)
ISSUED AT 305 PM EDT THU SEP 11 2014

THE ONLY REAL CHANCE FOR PRECIPITATION IS RAIN CENTERED AROUND THE
MONDAY TIME FRAME. FAIRLY GOOD CERTAINTY WITH THIS EVENT AS MODELS
HAVE SHOWN GOOD CONSISTENTLY BOTH AMONG EACH OTHER AND RUN TO RUN.
SLIGHT TIMING DIFFERENCES EXIST AS ONE WOULD EXPECT AT THIS TIME
RANGE. THE GFS IS A BIT FASTER...HAVING PRECIPITATION COMMENCE EARLY
MONDAY MORNING...WHEREAS THE FAVORED ECMWF AND FIM SOLUTIONS SHOW
RAIN BEGINNING DURING THE DAY. ALL SOLUTIONS SHOW PRECIP EXITING
MONDAY EVENING.

DRY CONDITIONS SHOULD PREVAIL AFTERWARDS WITH SURFACE HIGH PRESSURE
IN CONTROL AND SEASONABLY COOL HIGH TEMPERATURES.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 146 AM EDT FRI SEP 12 2014

THE MAIN CHALLENGES FOR AVIATION INTERESTS OVER THE NEXT 24 HOURS
WILL BE CIG TRENDS FOR THE FIRST HALF OF THE FCST PERIOD. THE
FOCUS WILL THEN SHIFT TO RAIN AND SOMEWHAT LOWER CONDITIONS
EXPECTED WITH A WAVE OF LOW PRESSURE MOVING THROUGH THE AREA.

CONDITIONS ARE IMPROVING A BIT ACROSS THE WRN TERMINALS EARLY THIS
MORNING. MVFR CONDITIONS ARE TRENDING VFR LIKELY DUE TO THE NE
WIND DRYING THE LOW LEVELS A BIT OVER THE WEST. WE EXPECT THIS
TREND TO CONTINUE...AND EVEN SOME LOWER IFR STRATUS IS STARTING TO
SHOW UP AT KLAN AND KJXN...AND COULD IMPACT KBTL SOON.

WE EXPECT THAT ALL SITES SHOULD GO VFR BY 16Z FRI OR SO. THIS WILL
LIKELY BE FOUND WITH A CIG AROUND 3500 FT AS THE LOWER CLOUDS LIFT
INTO A DIURNAL CUMULUS/STRATOCUMULUS DECK. RAIN WILL IMPACT AREAS
NW OF THE TERMINALS INITIALLY LATE FRI AFTERNOON. THE RAIN WILL
THEN GRADUALLY SPREAD SOUTH AND EAST THROUGH FRI EVENING. THE NE
FLOW SHOULD LIMIT CONDITIONS FROM BEING TOO LOW IN THE RAIN.

&&

.MARINE...
ISSUED AT 305 PM EDT THU SEP 11 2014

THE SMALL CRAFT ADVISORY REMAINS IN EFFECT THROUGH LATE TONIGHT.
NORTH FLOW COLD AIR ADVECTION WILL RESULT IN WAVE HEIGHTS IN THE
3 TO 5 FOOT RANGE THROUGH THEN. WAVE HEIGHTS WILL DIMINISH FRIDAY
AS WINDS VEER TO THE NE AND DIMINISH TO AOB 10 KTS.


&&

.HYDROLOGY...
ISSUED AT 305 PM EDT THU SEP 11 2014

NO HYDRO ISSUES ARE ANTICIPATED WITH DRY WX TONIGHT THROUGH FRIDAY
MORNING AND RELATIVELY LIGHT RAINFALL AMOUNTS OF ONLY AROUND A
QUARTER OF AN INCH ANTICIPATED FROM FRIDAY AFTERNOON THROUGH SATURDAY
MORNING.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 5 AM EDT EARLY THIS MORNING FOR
     LMZ844>849.

&&

$$

UPDATE...MJS
SYNOPSIS...LAURENS
SHORT TERM...LAURENS
LONG TERM...TJT
AVIATION...NJJ
HYDROLOGY...LAURENS
MARINE...LAURENS






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