Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 040729
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
329 AM EDT SAT JUL 4 2015

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

.SYNOPSIS...
ISSUED AT 329 AM EDT SAT JUL 4 2015

A NEARLY IDEAL WEATHER IS EXPECTED FOR OUR FOURTH OF JULY WEEKEND
OVER SOUTWHEST LOWER MICHIGAN. SKIES SHOULD BE MOSTLY CLEAR TODAY
AND SUNDAY HOWERVER NORTH AND EAST OF BIG RAPIDS THERE SCATTERED
THUNDERSTORMS ARE EXPECTED DURING THE MID TO LATE AFTERNOON. IT
WILL GET WARMER EACH DAY THROUGH MONDAY. HIGHS SHOULD BE NEAR 80
AWAY FROM THE LAKE MICHIGAN BEACHES TODAY...MID 80S SUNDAY AND
UPPER 80S FOR THE FIRST TIME THIS YEAR ON MONDAY.

A COLD FRONT WILL COME THROUGH THE AREA EARLY TUESDAY PRECEEDED BY
SHOWERS AND SCATTERED THUNDERSTORMS DURING THE EARLY MORNING HOURS
OF TUESDAY. AFTER THAT EXPECT PARTLY SUNNY SKIES WITH HIGHS FROM
THE MID 70S TO AROUND 80 THE REST OF THE WEEK.


&&

.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 329 AM EDT SAT JUL 4 2015

THE THERE ARE THREE ISSUES WE ARE CONSIDERING THIS WEEKEND. FIRST
IS THE THREAT FOR SCATTERED THUNDERSTORMS OVER OUR NORTHEAST CWA
THIS AFTERNOON...SECOND IS HOW WARM IT WILL GET EACH DAY AND
FINALY THE TIMING OF THE CONVECTION WITH THE COLD FRONT LATER
MONDAY OR MONDAY NIGHT (THAT IS MOSTLY IN THE LONG RANGE PART OF
THE FORECAST).

THE BIG PICTURE SHOWS OUR POLAR JET IS ALONG THE CANADIAN BOARD
FROM WESTERN CANADA INTO THE GREAT LAKES TODAY WITH TWO MARJOR
SHORTWAVES TO WATCH. THE FIRST IS TRACKING ALONG THE CANADIAN
BOARDER NEAR LAKE SUPERIOR THIS MORING AND WILL EXIT THE GREAT
LAKES SUNDAY OVER QUECBEC. THE SECOND ONE...WHICH IS MUCH
STRONGER...HAS A CLOSED UPPER LOW ASSOCAITED WITH IT AND IT TRIES
TO DIG INTO THE CENTRAL GREAT LAKE BY MONDAY...HOWEVER AND EVEN
STRONG SYSTEM UPSTREAM OF THAT WILL KEEP THIS LEAD SYSTEM FROM
DIGGING LIKE IT OTHWISE WOULD HAVE IF THE WAVELENGHT BETWEEN THE
TWO SYSTEMS HAD BEEN GREATER. IT IS THE TRAILING MUCH DEEP SYSTEM
FORECAST OVER WESTERN CANADA BY EARLY NEXT WEEK THAT WILL KEEP THE
REALLY COOL AIR IN CANDADA INSTEAD OF OVER US. IT WILL ASLO WEAKEN
THE FRONT THAT COMES THROUGH MONDAY NIGHT...DIMINISHING THE RISK
FOR SEVERE STORMS.

AS FOR TODAY...THE FIRST WEAK SHORTWAVE TRACKING THROUGH SOUTHERN
ONTARIO TODAY WILL HAVE THE JET CORE NORTH OF LAKE HURON BY MID
AFTERNOON. THE RESULTING LOW LEVEL JET WILL HAVE A 15 TO 20 KNOT
SPEED MAX OVER CENTRAL LAKE HURON. CLEARLY NOT AN IDEAL SET UP FOR
THUNDERSTORMS SINCE OUR NORTHEAST CWA IS IN THE RIGHT EXIT REGION
OF THE POLAR JET (CONVEGECNE ALOFT). MODEL SOUNDING CONFIRM THIS
BY SHOWING VERY DRY AIR ABOVE 700 MB. EVEN SO WE WILL HAVE A COLD
FRONT CREATING SURFACE CONVERGENCE AND MODEL SOUNDING STILL SHOW
UP TO 500 J/KG OF MOST UNSTABLE CAPE IN OUR NE CWA LATE THIS
AFTERNOON. I WOULD IMAIGNE WE WILL SEE SOME SCATTERED TO ISOLATED
STORMS NORTH AND EAST OF BIG RAPIDS BETWEEN...SAY 2 PM AND 6 PM.

ONCE OUT OF THE WAY WE GET SHORT TERM RIDGING FOR TONIGHT THROUGH
SUNDAY NIGHT. THIS LETS THE WARM AIR COME BACK IN AND WITH WEST TO
SOUTWEST WINDS THROUGH A DEEP LAYER I WOULD THICK THE FOREST FIRE
SMOKE PLUM WE HAVE BEEN SEEING OVER THE NORTHER MIDWEST WILL BE
OUT OF OUR AREA BY THEN. THAT WILL ALLOW FOR BETWEEN WARMING. I
PUT HIGHS IN THE MID 80S.

ON MONDAY WE HAVE THAT NEXT SHORTWAVE HEADING OUR WAY. THE MODELS
ARE ALL SHOWING THE PRECIPITATION BAND COMING INTO OUR AREA AFTER
MIDNIGHT MONDAY NIGHT. SO MONDAY WILL SEE DEEP MIXING AND ABUNDATN
SUNSHINE. I WOULD THINK HIGHS WILL BE PUSHING 90 BY MID AFTERNOON.

BOTTOM LINE...MOSTLY CLEAR SKIES AND WARMER TEMERATURES TODAY
THROUGH MOST OF MONDAY.


.LONG TERM...(MONDAY NIGHT THROUGH FRIDAY)
ISSUED AT 329 AM EDT SAT JUL 4 2015

SLIGHT DIFFERENCES IN THE MODELS ON THE TIMING OF A COLD FRONT...BUT
IT APPEARS TO COME THROUGH LATE MONDAY NIGHT/EARLY TUESDAY.  THIS
WILL BE DURING A MIN OF INSTABILITY...SO DESPITE BEING UNDER THE
RIGHT ENTRANCE REGION OF THE UPPER JET...SEVERE STORM CHANCES LOOK
MINIMAL AT THIS POINT.  THERE DOES APPEAR TO BE SOME ELEVATED
INSTABILITY...SO SOME OF THE STRONGER STORMS MAY PRODUCE HAIL.
STILL...THERE APPEARS TO BE FAVORABLE MOISTURE POOLING ALONG THE
FRONT...SO WILL MAINTAIN THE LIKELY POPS MONDAY NIGHT.  THE SHOWER
AND STORM COVERAGE SHOULD TREND DOWNWARD INTO TUESDAY AFTERNOON AS
THE FRONT DEPARTS.

IT WILL BE COOLER FOR MID WEEK WITH HIGHS BACK IN THE 70S.  DRY
WEATHER IS EXPECTED WEDNESDAY/WEDNESDAY NIGHT WITH HIGH PRESSURE
PASSING THROUGH.  THE MODELS SUGGEST A SHORT WAVE COMING THROUGH IN
THE THURSDAY/THURSDAY NIGHT TIME FRAME.  THE FLOW APPEARS RATHER
PROGRESSIVE...SO THE TIMING OF THIS WAVE IS SUBJECT TO CHANGE.  HAVE
20/30 POPS TO COVER THE WAVE.  SLIGHTLY WARMER AIR RETURNS THURSDAY
NIGHT INTO FRIDAY.


&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 112 AM EDT SAT JUL 4 2015

VFR CONDITIONS WILL CONTINUE THROUGH THE NEXT 24 HOURS ALONG WITH
A LIGHT WESTERLY WIND. THERE COULD BE SOME VERY PATCHY LIGHT FOG
TOWARD MORNING...BUT IT IS NOT EXPECTED TO BECOME ANY WORSE THE
MVFR.


&&

.MARINE...
ISSUED AT 329 AM EDT SAT JUL 4 2015

HIGH PRESSURE MEANS NO HEADLINES NEEDED. ONCE THE WINDS BECOME
MORE WESTERLY OVER LAKE MICHGIAN THE WATER TEMPERATURES WILL RISE
BACK INTO THE 60S OVER THE BEACHES...THAT WILL RESULT IN MORE
PLESANT BEACH WEATHER SUNDAY INTO MONDAY (STORMS COME IN AFTER
DARK)

&&

.HYDROLOGY...
ISSUED AT 1136 AM EDT FRI JUL 3 2015

SIGNIFICANT IMPROVEMENT CONTINUES ON AREA RIVERS. THE LONE
ADVISORY AT HOLT ON THE SYCAMORE CREEK IS EXPECTED TO RECEDE BELOW
ITS BANKS WITHIN THE NEXT 24 HOURS OR SO.

THERE IS MINIMAL THREAT FOR RAINFALL OVER THE NEXT FEW DAYS.
ISOLATED SHOWERS/THUNDERSTORMS ARE POSSIBLE THROUGH PORTIONS OF
CENTRAL LOWER MICHIGAN SATURDAY AFTERNOON WITH VERY BRIEF AND
LOCALIZED DOWNPOURS POSSIBLE. OTHERWISE...DRY WEATHER WILL
CONTINUE THROUGH THE NEXT THREE DAYS AND THROUGH THE MAJORITY OF
MONDAY. A COLD FRONT WILL BRING IN THE NEXT ROUND OF RAIN LATE
MONDAY EVENING. EXPECTED AMOUNTS ARE RATHER TYPICAL OF SUMMER
CONVECTION WITH POCKETS OF HEAVIER RAINFALL POSSIBLE.

&&

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

$$

SYNOPSIS...WDM
SHORT TERM...WDM
LONG TERM...JK
AVIATION...JK
HYDROLOGY...JAM
MARINE...WDM



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