Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 301206
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
806 AM EDT WED JUL 30 2014

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 330 AM EDT WED JUL 30 2014

MORE OF THE SAME WEATHER FROM THE PAST COUPLE OF DAYS CAN BE
EXPECTED INTO THE WEEKEND. WAVES OF LOW PRESSURE WILL BE MOVING
THROUGH THE AREA ON OCCASION...BRINGING CHANCES OF A FEW SHOWERS AND
STORMS. THE BEST CONCENTRATION OF PRECIPITATION WILL GENERALLY COME
DURING THE AFTERNOON AND EARLY EVENING HOURS DURING PEAK HEATING.
AREAS FURTHER AWAY FROM LAKE MICHIGAN WILL GENERALLY SEE THE BEST
CHANCES. TEMPERATURES WILL WARM A COUPLE OF DEGREES EACH DAY...
COMING CLOSER TO EXPECTED TEMPERATURES FOR LATE JULY/EARLY AUGUST.

&&

.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 330 AM EDT WED JUL 30 2014

THE PATTERN OF A FEW OCCASIONAL SHOWERS AND STORMS WILL PERSIST
THROUGH THE SHORT TERM PERIOD THROUGH THE DAY ON FRIDAY. OUR
CHALLENGE IS TO DETERMINE WHEN AND WHERE THE BETTER THREAT OF PCPN
WILL OCCUR. SEVERE WEATHER IS NOT A BIG CONCERN AT THIS TIME AS
DECENT INSTABILITY AND SHEAR NEVER REALLY COINCIDE WITH EACH OTHER
THROUGH FRIDAY.

A FEW LIGHT SHOWERS ARE TRYING TO DRIFT INTO THE NRN PORTION OF THE
CWFA EARLY THIS MORNING FROM THE NORTH. ENOUGH FORCING WITH A SHORT
WAVE MOVING IN FROM NRN LAKE MICHIGAN IS OVERCOMING THE RELATIVE MIN
IN DIURNAL INSTABILITY TO PRODUCE THESE LIGHT SHOWERS. THESE WILL
REMAIN POSSIBLE THROUGH THE CWFA THROUGH MID MORNING WHEN THIS SHORT
WAVE WILL EXIT THE STATE.

THE BEST CHC OF SHOWERS AND A STORM WILL COME EARLY TO MID AFTERNOON
TOWARD THE SE PORTION OF THE AREA. A SFC TROUGH/WEAK COLD FRONT WILL
ALSO BE PRESSING THROUGH THE AREA AHEAD OF ANOTHER SHORT WAVE NOW
ACROSS THE U.P. AND WILL REACH THE SE CORNER OF THE AREA TOWARD PEAK
HEATING. MODELS ARE BRINGING IN AS MUCH AS 700 J/KG OF CAPE TO THE
KJXN AREA AHEAD OF THESE FEATURES. A FEW STORMS WITH SOME HAIL WILL
BE POSSIBLE...BUT DEEP LAYER SHEAR VALUES AROUND 20 KNOTS OR SO
SHOULD LIMIT A SEVERE THREAT. AREAS IN THE WAKE OF THIS SHORT WAVE
WILL SEE SOME SUBSIDENCE BUILD IN AND DRIER AIR THAT WILL LIMIT
SHOWER/STORM DEVELOPMENT. A WRLY COMPONENT TO THE WIND OFF OF THE
LAKE WILL ALSO LIMIT DEVELOPMENT.

THE NEXT CHC OF SOME SHOWERS WILL COME DURING THE SECOND HALF OF THE
TONIGHT PERIOD AND INTO THU. ANOTHER FRONT/SHORT WAVE WILL APPROACH
THE AREA LATER TONIGHT...BRINGING A LOW CHC OF SHOWERS TO NRN AREAS.
THIS CHC WILL SPREAD SOUTH ON THU AN INCREASE A BIT IN THE AFTERNOON
AWAY FROM LAKE MICHIGAN WITH A FEW HUNDRED J/KG OF CAPE DEVELOPING
ONCE AGAIN. ONCE AGAIN LIMITED DEEP LAYER SHEAR WILL LIMIT THE
ORGANIZATION OF THE STORMS.

THE THREAT FOR A SHOWER OR STORM WILL HOLD IN FOR THU NIGHT AND
CONTINUE INTO FRI. THE FRONT TRYING TO START DROPPING DOWN ON THU
WILL PRETTY MUCH STALL OUT AND REMAIN OVER THE CWFA. THERE IS NO
REAL SUPPORT TO BRING A GOOD CONCENTRATION OF STORMS TO THE AREA
ASIDE FROM THE WEAKENING FRONT ITSELF. CAPE VALUES INCREASE A LITTLE
MORE FOR FRI WITH DEW POINTS INCHING UP AHEAD OF THE FRONT AND TEMPS
AROUND 80 OR SO. DEEP LAYER SHEAR DIMINISHES FROM INITIALLY LIMITED
VALUES TO START WITH...SO SEVERE WX IS NOT A BIG CONCERN.

.LONG TERM...(FRIDAY NIGHT THROUGH TUESDAY)
ISSUED AT 330 AM EDT WED JUL 30 2014

UPPER TROUGH STILL LINGERS INTO THE LONG TERM...BUT IT WILL NOT BE
NEARLY AS DEEP. THE CORE WILL HAVE LIFTED OUT TO THE NORTHEAST
ACROSS CANADA BY THE LONG TERM. THAT SAID...THERE IS SOME GENERAL
TROUGHING THAT PERSISTS RIGHT THROUGH THE WEEKEND. EARLY NEXT WEEK
THE FLOW BECOMES A BIT MORE PROGRESSIVE OUT OF THE WEST-NORTHWEST.

FRIDAY NIGHT THROUGH SATURDAY NIGHT MUCH OF THE SAME PATTERN THAT IS
PRESENT IN THE SHORT TERM WILL LINGER INTO THE LONG TERM. DIURNAL
FLARE UP IN SHOWER AND STORM ACTIVITY IS EXPECTED. SO...SOME
SCATTERED SHOWERS AND STORMS WILL LINGER INTO FRIDAY NIGHT BEFORE
FADING. SATURDAY/S CONVECTION WILL LINGER INTO THE EVENING HOURS AS
WELL BEFORE ENDING. PRECIP CHANCES WILL BE BETTER INLAND AWAY FROM
THE COOLING AFFECTS OF THE LAKE BREEZE NEAR LAKE MICHIGAN.

HAVE A DRY FORECAST SUNDAY AND SUNDAY NIGHT AS HIGH PRESSURE WORKS
THROUGH THE AREA.

A FRONT WILL SLIDE INTO THE REGION ON MONDAY AND STALL OUT INTO
TUESDAY. SHOWER AND STORM CHANCES RETURN TO THE FORECAST DURING THIS
TIME FRAME.

HIGHS THROUGH THE PERIOD WILL BE SEASONABLE FROM AROUND 80 TO THE
LOWER 80S.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 805 AM EDT WED JUL 30 2014

FOG WILL LIFT THROUGH THE COURSE OF THE MORNING...WITH VFR
CONDITIONS EXPECTED AT ALL TAF SITES BY 15Z TO 16Z. LIFR
CONDITIONS ARE OCCURRING AT PRESENT AT KLAN. THIS SHOULD LIFT
FAIRLY QUICK GIVEN DAYTIME HEATING.

SCATTERED SHOWERS AND EVEN A FEW THUNDERSTORMS WILL BE POSSIBLE
THROUGH THE COURSE OF THE DAY. NOT CONFIDENT ENOUGH IN THE AREAL
EXTENT OF THE STORMS TO INCLUDE IN THE TAFS...SO ONLY HAVE VCSH
MENTIONED AT THIS POINT.

AFTER THE MORNING FOG...GENERALLY EXPECTING VFR CONDITIONS THE
NEXT 24 HOURS.


&&

.MARINE...
ISSUED AT 655 AM EDT WED JUL 30 2014

HAVE OPTED TO ISSUE A MARINE DENSE FOG ADVISORY THROUGH THE
AFTERNOON FROM SOUTH HAVEN NORTH UP THE SHORE TO MANISTEE. WEBCAMS
SHOW THICK FOG AT LEAST AT HOLLAND AND MUSKEGON WITH OTHER CAMS
SHOWING SOME FOG AS WELL. THE COLD WATER THAT HAS BEEN BROUGHT TO
THE SURFACE FROM RECENT WAVE EVENTS HAS AIDED IN CREATING THICK
FOG. EXPECTING IT TO LIFT SOMEWHAT THROUGH THE COURSE OF THE DAY
WITH DAYTIME HEATING/MIXING BUT WANT TO GIVE A BUFFER INTO THE
AFTERNOON JUST IN CASE IT HOLDS ON. WE CAN ALWAYS DROP IT EARLY IF
IT LIFTS QUICKER. FOG WILL LIKELY REMAIN A THREAT...AT LEAST OFF AND
ON THROUGH THE END OF THE WEEK AS THE COLD WATER PERSISTS AND DEW
POINTS GRADUALLY INCREASE.

WINDS AND WAVES WILL NOT REALLY BE AN ISSUE...LIKELY THROUGH MOST OF
THE REST OF THE WEEK FOR THE AREA. WINDS SHOULD BE MAINLY 15 KNOTS
OR LESS THROUGH THE PERIOD.


&&

.HYDROLOGY...
ISSUED AT 330 PM EDT TUE JUL 29 2014

NO HYDRO CONCERNS AT THIS TIME GIVEN WIDELY SCATTERED NATURE OF
THE CONVECTION OVER THE NEXT FEW DAYS. SOME BRIEF LOCALLY HEAVY
DOWNPOURS WITH SMALL HAIL MAY OCCUR IN ANY OF THE HEALTHIER CELLS.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...DENSE FOG ADVISORY UNTIL 4 PM EDT THIS AFTERNOON FOR LMZ845>849.

&&

$$

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





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