Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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000
FXUS63 KGRR 210344
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1144 PM EDT SUN JUL 20 2014

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 314 PM EDT SUN JUL 20 2014

FAIR WEATHER WILL CONTINUE THROUGH TUESDAY WITH A GRADUAL RISE IN
TEMPERATURES TO UPPER 80S BY TUESDAY WITH 90 DEGREES POSSIBLE IN
SPOTS. SHOWERS AND THUNDERSTORMS WILL MOVE SOUTHEAST THROUGH THE
AREA FROM LATE TUESDAY THROUGH EARLY WEDNESDAY. THIS WILL BE
FOLLOWED BY MORE SEASONAL TEMPERATURES AND DRY CONDITIONS FOR THE
REST OF THE WORK WEEK. A CHANCE OF SHOWERS AND THUNDERSTORMS RETURNS
FOR THE WEEKEND.

&&

.SHORT TERM...(THIS EVENING THROUGH TUESDAY NIGHT)
ISSUED AT 314 PM EDT SUN JUL 20 2014

PREVIOUS FORECAST LOOKS ON TRACK. FAIRLY HIGH CONFIDENCE IN SHOWERS
AND THUNDERSTORMS ENTERING THE AREA FROM THE NORTHWEST TUESDAY
AFTERNOON/EVENING AND OVERSPREADING THE AREA TUESDAY NIGHT.

SPC CALIBRATED SREF GUIDANCE INDICATES A LOW CONDITIONAL PROBABILITY
FOR SEVERE THUNDERSTORMS BASED ON WEAK SHEAR /0-6 KM BULK SHEAR < 20
KT/ AND UNFAVORABLE DIURNAL TIMING. HOWEVER...MARGINALLY SEVERE
CONVECTIVE WIND GUSTS WILL BE POSSIBLE TUESDAY AFTERNOON/EVENING
OVER OUR NORTHWEST FORECAST AREA. THIS IS WHERE A DEEP MIXED LAYER
WITH SURFACE TEMPERATURES IN THE UPPER 80S WILL BE PRESENT AHEAD OF
THE APPROACHING COLD FRONT. ALSO...THE SPC DAY3 OUTLOOK SUGGESTS
THAT A RESIDUAL MCV COULD CROSS THE LAKE FROM EARLIER CONVECTION
OVER WI. ALL OF THIS IS HIGHLY SPECULATIVE AT THIS POINT...BUT
CERTAINLY WORTH WATCHING.

.LONG TERM...(WEDNESDAY THROUGH SUNDAY)
ISSUED AT 314 PM EDT SUN JUL 20 2014

THE MOST NOTEWORTHY WEATHER IN THE LONG TERM WILL HAPPEN IMMEDIATELY
AT THE BEGINNING...AND THEN AT THE END OF THE PERIOD. A NICE PERIOD
OF WEATHER IS EXPECTED IN THE MIDDLE.

WE HAVE CONTINUED THE FASTER TREND OF THE SHOWERS AND STORMS WITH
THE COLD FRONT DURING THE DAY ON WED. IT NOW LOOKS LIKE THE SE HALF
OF THE CWFA HAS THE ONLY REAL CHC OF SHOWERS/STORMS WED MORNING
BEFORE THE FRONT PUSHES THROUGH. SEVERE WX LOOKS UNLIKELY WITH THE
TIMING OF THE FRONT THROUGH DURING THE MIN IN INSTABILITY. IT SEEMS
THAT THE LONG WAVE TROUGH EXTENDING FROM WELL NORTH IN CANADA WILL
HELP PUSH THE FRONT THROUGH QUICKER AS IT ABSORBS THE SHORT WAVE
COMING IN FROM THE WEST.

THE PERIOD FROM WED AFTERNOON THROUGH AT LEAST FRI IF NOT SAT WILL
BE A COMFORTABLE AND DRY PERIOD FOR THE AREA. WE WILL BECOME UNDER
THE INFLUENCE OF STRONG SUBSIDENCE DURING THIS TIME FRAME IN THE
WAKE OF THE TUE NIGHT/WED MORNING TROUGH. A FAIRLY AMPLIFIED UPPER
FLOW PATTERN WILL HAVE A STRONG RIDGE AXIS OVER THE PLAINS AND MI
JUST DOWNSTREAM OF IT. WE WILL SEE A CANADIAN AIR MASS SETTLE IN
FROM NRLY FLOW WITH H850 TEMPS AROUND 8-10C ADVECTING IN. THE AIR
MASS WILL GRADUALLY MODERATE BACK INTO THE TEENS C ON FRI HELPING
GET TEMPS BACK UP INTO THE 80S.

INDICATIONS ARE THAT NEXT WEEKEND LOOKS TO BE SOMEWHAT UNSETTLED
WITH SHOWER AND STORM CHANCES COMING BACK FOR NEXT WEEKEND. AN UPPER
LOW EXPECTED TO DEVELOP ACROSS THE PACIFIC NW MID WEEK AND HELP WITH
THE AMPLIFIED FLOW WILL GRADUALLY ROTATE INTO THE AREA NEXT WEEKEND.
WE WILL SEE THE LEADING EDGE OF WARM AND MOIST ADVECTION MOVE IN ON
SAT BRINGING CHCS OF SHOWERS AND STORMS. EVENTUALLY THE LOW ITSELF
WILL MOVE OVERHEAD ON SUN OR BEYOND AND PROVIDE MORE SHOWERY TYPE OF
WEATHER AND COOLER CONDITIONS.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1144 PM EDT SUN JUL 20 2014

EXPECT MOSTLY VFR CONDITIONS TO PREVAIL THROUGH MONDAY. THE I-96
TAF SITES MAY HAVE A PERIOD OF MVFR FOG IN THE 09Z TO 12Z TIME
FRAME HOWEVER. MONDAY SHOULD BE MOSTLY SUNNY WITH A FEW HIGH BASED
CUMULUS CLOUDS AND LIGHT SOUTH WINDS.

&&

.MARINE...
ISSUED AT 314 PM EDT SUN JUL 20 2014

BASED ON WEBCAMS AND FOLLOWING THE LEAD OF THE CHICAGO NWS FOR THE
OPEN WATERS...HAVE INCLUDED THE MENTION OF HAZE THE REST OF THIS
AFTERNOON. OTHERWISE...EXPECT WINDS FROM THE SOUTH/SOUTHWEST TO
INCREASE TUESDAY AHEAD OF AN APPROACHING COLD FRONT. THIS MAY
REQUIRE A SMALL CRAFT ADVISORY TUESDAY NORTH OF WHITEHALL AND
POSSIBLY EVEN POINTS FARTHER SOUTH.


&&

.HYDROLOGY...
ISSUED AT 314 PM EDT SUN JUL 20 2014

QPF FOR TUESDAY NIGHT AND WEDNESDAY WILL NOT BE ENOUGH TO CAUSE ANY
SIGNIFICANT RESPONSE ON MAIN STEM RIVERS AND LITTLE RESPONSE IS
EXPECTED ON SMALL RIVERS AND STREAMS. THEREFORE...WE DO NOT
ANTICIPATE FLOODING CONCERNS THIS WEEK. MAPLE RAPIDS HAS FALLEN
BELOW BANKFULL AND WILL CONTINUE DROPPING. OTHER RIVERS ARE RUNNING
NEAR TO ABOVE NORMAL BUT WELL WITHIN BANKS.

&&

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

$$

SYNOPSIS...TJT
SHORT TERM...TJT
LONG TERM...NJJ
AVIATION...WDM
HYDROLOGY...HOVING
MARINE...TJT





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