Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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000
FXUS63 KGRR 291723
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
123 PM EDT WED JUL 29 2015

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 330 AM EDT WED JUL 29 2015

SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED TODAY AS A COLD
FRONT CROSSES THE REGION. GUSTY WESTERLY WINDS BEHIND THE FRONT WILL
USHER IN MORE COMFORTABLE LESS HUMID AIR FOR THE REMAINDER OF THE
WEEK ALTHOUGH HIGHS WILL REMAIN IN THE LOWER TO MID 80S.

&&

.UPDATE...
ISSUED AT 1044 AM EDT WED JUL 29 2015

DECREASED POPS A BIT BASED ON RADAR TRENDS. A WEAK COLD FRONT IS
MOVING ACROSS LAKE MICHIGAN ATTM AND MAY KICK OFF A STORM OR TWO
THIS AFTERNOON MAINLY ACROSS THE EASTERN CWA.

&&

.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 330 AM EDT WED JUL 29 2015

ISOLATED SHOWERS HAVE DEVELOPED OVERNIGHT ON THE LEADING EDGE OF THE
HIGHER PRECIPITABLE WATER AROUND TWO INCHES MOVING IN FROM THE
SOUTHWEST AHEAD OF THE APPROACHING COLD FRONT. SUSPECT COVERAGE OF
SHOWERS WILL REMAIN RATHER LIMITED THIS MORNING ACROSS SW LWR MI AS
MORE EXPANSIVE AREA OF CONVECTION IMPACTS IOWA AND ILLINOIS.

OUR BEST PROSPECT FOR BETTER COVERAGE OF STORMS WILL BE THIS
AFTERNOON EAST OF HIGHWAY 131 WHERE SB CAPES NEAR 1500 J/KG ARE
PROGGED JUST AHEAD OF THE FRONT. RUC FCST SOUNDINGS EXHIBIT STEEP
LOW LEVEL LAPSE RATES WITH SFC TO 3 KM VALUES AROUND 8.5C NEAR
JXN. BASED ON THE HIGH PWAT VALUES OF UP TO 2.25 INCHES WE WILL
HAVE TO WATCH FOR THE POSSIBILITY OF SOME TORRENTIAL RAINFALL AND
POSSIBLY A LOCALIZED WET MICROBURST DAMAGING WIND EVENT.

CONVECTION ENDS FROM WEST TO EAST 18Z-22Z WITH THE PASSAGE OF THE
FRONT THEN DECREASING CLOUDS AND FALLING SFC DEW PTS EXPECTED.
BREEZY CONDITIONS LIKELY THURSDAY ONCE DEEPER MIXING COMMENCES.
SOME GUSTS TO 30 MPH WILL BE POSSIBLE IN THE AFTERNOON.

HAVE KEPT FRIDAY DRY FOR NOW ALTHOUGH SOME SMALL POPS MAY NEED TO
BE ADDED IN LATER FCSTS AS NEXT WEAK SFC FRONT/TROUGH DROPS SOUTH.

.LONG TERM...(FRIDAY NIGHT THROUGH TUESDAY)
ISSUED AT 330 AM EDT WED JUL 29 2015

THERE HAS NOT BEEN MUCH CHANGE OVER THE THE PAST FEW DAYS WITH
REGARD TO THE EXPECTED PATTERN. WE CONTINUE TO EXPECT LITTLE TO NO
RAIN THROUGH SAT...BEFORE AN UNSETTLED WEATHER PATTERN TAKES SHAPE
LATER THIS WEEKEND AND INTO NEXT WEEK.

WE HAVE CONTINUED WITH A DRY FCST FOR THE FRI NIGHT AND SAT TIME
FRAME FOR NOW. WE WILL SEE WHAT IS LEFT OF THE WEAKENING COLD FRONT
TRYING TO MOVE THROUGH ON FRI SLIP SE OF THE AREA FRI EVENING. WE
CAN NOT RULE OUT A SHOWER DEVELOPING NEAR THIS FRONT...HOWEVER THE
CHC IS LOW ENOUGH TO LEAVE OUT OF THE FCST FOR THE TIME BEING. A
LACK OF MOISTURE WITH THE FRI FRONT WILL ONLY DIMINISH BY SAT AS THE
FRONT MOVES OUT. THERE IS NOT REALLY SIGNIFICANTLY COOLER AIR BEHIND
THIS...SO WE CONTINUE TO EXPECT HIGHS AROUND 80.

THE CHCS OF RAIN DOES GO UP ON SUN...AND WILL CONTINUE THROUGH THE
END OF THE PERIOD ON TUE. THE AREA WILL BE UNDER THE INFLUENCE OF
BROAD LONG WAVE TROUGHING CENTERED WELL NORTH IN CANADA. WE WILL SEE
THE JET CORE DROP A LITTLE FURTHER SOUTH WITH A TRAIN OF SHORT WAVES
HELPING THIS CAUSE. BEING CLOSER TO THE JET...WE WILL HAVE MORE OF
AN OPPORTUNITY FOR THE SHORT WAVES TO DIRECTLY IMPACT THE AREA. WE
WILL ALSO SEE THE LOW LEVEL FLOW BECOME A LITTLE MORE FAVORABLE TO
BRING SUFFICIENT MOISTURE TO THE AREA FOR RAIN. EXACT TIMING OF THE
SHORT WAVES WILL BE PROBLEMATIC AS IS USUAL IN A PATTERN LIKE THIS.

TEMPERATURES DO NOT LOOK TO BE TOO BAD IN THIS PATTERN. THE
UNSEASONABLY COOL AIR WILL REMAIN JUST NORTH OF THE STATE...NORTH OF
THE JET CORE. WE WILL SEE AVERAGE TO JUST SLIGHTLY BELOW AVERAGE
TEMPS DURING THIS PERIOD FOR OUR AREA. THIS EQUATES TO HIGHS
GENERALLY AROUND 80 AND LOWS AROUND 60.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 122 PM EDT WED JUL 29 2015

THERE IS A NARROW BAND OF MVFR CIGS THAT TRAIL THE FRONT...THIS
WILL LAST ABOUT 2 HOURS AT ANY ONE STATION. IT HAS ALREADY CLEARED
THE MKG TAF SITE AND SHOULD BE CLEARING THE GRR...AZO AND BTL TAF
SITES BY 20Z. AHEAD OF THE FRONT CONVECTION IS STARTING TO DEVELOP
SO THE LAN AND JXN TAF SITES COULD SEE A THUNDERSTORM PRIOR TO THE
PASSAGE OF THE FRONT. THE FRONT SHOULD BE PASSING THROUGH THOSE
TAF SITES BY 21Z.

TONIGHT SKIES SHOULD BE CLEAR AND WINDS SHOULD BE SOUTHWEST UNDER
10 KNOTS. WINDS WILL INCREASE TO 10 TO 20 KNOTS AND GUSTY THURSDAY
AS COOLER AIR AT MID LEVELS MOVES IN. SKIES SHOULD REMAIN CLEAR OR
AT LEAST NEARLY  SO.

&&

.MARINE...
ISSUED AT 330 AM EDT WED JUL 29 2015

CONDITIONS MAY APPROACH SMALL CRAFT ADVISORY CRITERIA LATE TONIGHT
AND EARLY THURSDAY DUE TO STRONG WESTERLY FLOW BEHIND THE COLD
FRONT. THIS WILL NEED TO BE MONITORED. THIS SITUATION COULD ALSO
SUPPORT BEACH HAZARD STATEMENTS ESPECIALLY CONSIDERING THE CURRENT
WARM WATER TEMPERATURES AND OVERALL ATTRACTIVE BEACH CONDITIONS
SUPPORTIVE OF A HIGH BEACH POPULATION.


&&

.HYDROLOGY...
ISSUED AT 1151 AM EDT WED JUL 29 2015

RIVER LEVELS ARE FALLING AND WELL BELOW BANKFULL. THE MAIN CHANCE OF
RAIN IN THE NEXT 7 DAYS WOULD BE SUNDAY INTO MONDAY NIGHT. LOCALLY
HEAVY RAIN IS POSSIBLE... BUT ONLY PONDING OF WATER IS EXPECTED AWAY
FROM THE RIVERS. RIVERS MAY SHOW RISES... BUT SHOULD NOT REACH BANK
FULL LEVELS.

&&

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

$$

UPDATE...04
SYNOPSIS...MEADE
SHORT TERM...MEADE
LONG TERM...NJJ
AVIATION...WDM
HYDROLOGY...63
MARINE...MEADE



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