Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 291628 CCA
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1230 PM EDT TUE JUL 29 2014

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 1150 AM EDT TUE JUL 29 2014

A RELATIVELY COOL AND UNSETTLED PERIOD OF WEATHER FOR LATE JULY IS
EXPECTED TO CONTINUE THROUGH MOST OF THE REST OF THIS WEEK. THE AREA
WILL SEE HIGH TEMPERATURES MAINLY IN THE 70S THROUGH THE END OF THE
WEEK. WEAK WAVES OF LOW PRESSURE WILL PASS THROUGH THE AREA THROUGH
THE WEEK. THIS WILL PROVIDE SOME SHOWER AND STORM CHANCES MAINLY
DURING THE AFTERNOON AND EARLY EVENING HOURS. THERE WILL BE MANY
HOURS DURING EACH DAY FOR ANY ONE LOCATION THAT IT WILL NOT BE
RAINING.

&&

.MESOSCALE UPDATE...
ISSUED AT 1155 AM EDT TUE JUL 29 2014

LATEST RAP FCST SNDGS FOR THIS AFTERNOON AROUND LAN/JXN SHOW ONLY
ABOUT 500-800 JOULES OF SKINNY CAPE TO WORK WITH. NOT TOO
IMPRESSIVE BUT JUST ENOUGH TO POP A FEW CELLS DURING PEAK HEATING.
IN ADDITION TO THE SMALL HAIL THREAT RELATED TO THE LOW FRZG
LVLS... A GUSTY WIND THREAT PROBABLY EXISTS AS WELL AS FCST SNDGS
HAVE INVERTED-V LOOK BY MID TO LATE AFTERNOON WITH CONVECTIVE
CLOUD BASES AROUND 7K FT. THE BEST SFC CONVERGENCE CONTINUES TO BE
PROGGED EAST OF HWY 131 ON THE LAKE BREEZE SHADOW. CONVECTIVE
TEMPS ARE IN THE MID TO UPPER 60S AND THE DIURNAL CUMULUS IS
ALREADY POPPING. MODERATE TO TOWERING CU SHOULD DEVELOP BY 2PM WITH
LITTLE TO TO CIN CURRENTLY PRESENT.

&&

.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 328 AM EDT TUE JUL 29 2014

THE MAIN FOCUS OF THE FCST WILL BE ON THE TRENDS FOR RAIN CHCS EACH
DAY AND WHAT IF ANY SEVERE CHCS WILL BE PRESENT. THE UPPER LOW
CENTERED NEAR HUDSON AND JAMES BAYS WILL REMAIN IN CONTROL OF THE
WEATHER ACROSS THE STATE/REGION. SHORT WAVES WILL CONTINUE TO ROTATE
IN ACROSS THE AREA FROM THE NNW AS WE REMAIN UNDER THE CYCLONIC FLOW
OF THE LOW.

THERE ARE A COUPLE OF LIGHT RAIN SHOWERS NEAR MANISTEE AS OF 07Z
THIS MORNING HEADING TO THE SE. THESE RAIN SHOWERS ARE DIRECTLY
RELATED TO A SHORT WAVE THAT IS COMING IN FROM NRN LAKE MICHIGAN. WE
WILL SEE A FEW SHOWERS REMAIN POSSIBLE THROUGH 12-14Z WITH THIS AS
IT PROGRESSES SE OUT OF THE CWFA BY THAT TIME.

WE WILL THEN SEE THE THREAT FOR SHOWERS AND STORMS INCREASE QUITE A
BIT THIS AFTERNOON. SOME CONVECTION THAT IS ONGOING NW OF LAKE
SUPERIOR EARLY THIS MORNING WITH A SHORT WAVE WILL GRADUALLY SHIFT
SSE INTO THE REGION THIS AFTERNOON DURING PEAK HEATING. HI RES
MODELS ARE INDICATING THAT THE BULK OF THE CONVECTION WITH THIS WAVE
WILL BE ACROSS WI AND CENTRAL AND ERN LOWER MI. THERE CONTINUES TO
BE GOOD AGREEMENT THAT WRLY WINDS WILL LIMIT INSTABILITY IMMEDIATELY
DOWNWIND OF LAKE MICHIGAN AND LIMIT CONVECTION THERE AS A RESULT.

WE AGREE WITH THE SWODY1 FROM SPC THAT THE SEVERE THREAT IS LIMITED
IN OUR NECK OF THE WOODS THIS AFTERNOON. FCST SOUNDINGS INDICATE
RELATIVELY THIN CAPE PROFILES. THIS AND PATTERN RECOGNITION WITH THE
UPPER LOW WOULD POINT TOWARD HAIL OCCURRING WITH THE STORMS...BUT
STAYING SUB-SEVERE WITH CAPE IN THE -10 TO -30C LAYER NOT OVERLY
IMPRESSIVE. WE CAN NOT RULE OUT SOME WIND GUSTS...BUT LIMITED MID
LEVEL WINDS BELOW 40 KNOTS SHOULD KEEP WIND GUSTS SUB-SEVERE ALSO.

AFTER AN EXPECTED LULL IN THE PCPN AFTER EARLY THIS EVENING THROUGH
WED MORNING...ADDITIONAL SHOWERS AND A FEW STORMS WILL BE POSSIBLE
ONCE AGAIN WED AFTERNOON. THE THREAT LOOKS TO BE MORE SE ON WED
AFTERNOON AS A SHORT WAVE AND ASSOCIATED SFC TROUGH ARE OVER THE SE
CORNER OF THE CWFA DURING PEAK HEATING. THE LAKE WILL ALSO LIMIT
INSTABILITY IMMEDIATELY DOWNWIND OF THE LAKE WITH WRLY FLOW AGAIN.
SHORT WAVE RIDGING WILL LIKELY LIMIT CONVECTION A LITTLE ELSEWHERE.
AGAIN. FCST SOUNDINGS INDICATE SOME HAILERS WILL BE LIKELY.

WE WILL REPEAT THE SITUATION ON THU...ALTHOUGH INSTABILITY LOOKS A
LITTLE MORE LIMITED AS TEMPS ALOFT LOOK TO WARM SLIGHTLY. WINDS
ALOFT ALSO DROP OFF A LITTLE...WHICH WILL ALSO LIMIT THE WIND THREAT
A LITTLE MORE.

.LONG TERM...(THURSDAY NIGHT THROUGH MONDAY)
ISSUED AT 328 AM EDT TUE JUL 29 2014

UPPER TROUGHING WILL BE WELL ESTABLISHED AT THE BEGINNING OF THE
LONG TERM (THURSDAY NIGHT) OVER THE EASTERN HALF OF THE LOWER 48.
THE TROUGH WILL BE CENTERED FROM ONT/QUE THROUGH THE GREAT LAKES.
THIS WILL REMAIN THE CASE THROUGH SATURDAY. SUNDAY/MONDAY THE TROUGH
LIFTS OUT SOMEWHAT WITH A GENERAL NORTHWEST FLOW IN PLACE.

AT THE SURFACE VERY WEAK FEATURES TO KEY ON WITH OCCASIONAL TROUGHS
ASSOCIATED WITH MID LEVEL SHORTWAVES MOVING THROUGH. TIMING OF THESE
FEATURES IS SOMEWHAT DIFFICULT AND VARY FROM THE GFS TO THE ECMWF.

AIR MASS WILL HAVE MODIFIED BY THE LONG TERM AND GENERALLY THINKING
HIGHS WILL BE RIGHT NEAR NORMALS FOR THIS TIME OF YEAR...AROUND 80
TO THE LOWER 80S.

SENSIBLE WEATHER WILL FEATURE AFTERNOON AND EVENING SHOWERS AND
STORMS FRIDAY AND SATURDAY AS THE UPPER TROUGH ENHANCES INSTABILITY.
ECMWF BRINGS A FRONT THROUGH THE AREA ON MONDAY OF NEXT WEEK...WHERE
THE GFS IS MORE WRAPPED UP WITH ITS SURFACE LOW AND DELAYS THIS
UNTIL TUESDAY. AT THIS POINT HAVE SMALL POPS...20 PCT IN THE
FORECAST FOR NEXT MONDAY INTO TUESDAY TO PLAY A BIT OF A MIDDLE
GROUND WITH THE FRONTAL PASSAGE.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY)
ISSUED AT 1230 PM EDT TUE JUL 29 2014

VFR CONDITIONS ARE ANTICIPATED THROUGH 18Z WEDNESDAY. CIGS WITH
CLOUD BASES OF 3500-5000FT ARE EXPECTED MUCH OF THE TIME. A FEW
SHOWERS MAY DEVELOP MAINLY AT OUR EASTERN TERMINALS FROM MID TO LATE
AFTERNOON INTO EARLY EVENING BEFORE ENDING.

A COUPLE OF ISOLATED STORMS ARE POSSIBLE MID TO LATE AFTERNOON BUT
THERE IS NOT ENOUGH CONFIDENCE IN CONVECTIVE POTENTIAL TO WARRANT
INCLUSION IN THE TERMINAL FORECASTS. ANY HEAVIER SHOWERS MAY CAUSE
CONDITIONS TO BRIEFLY DETERIORATE TO MVFR CONDITIONS.

&&

.MARINE...
ISSUED AT 1155 AM EDT TUE JUL 29 2014

TWO NORTH FLOW UPWELLING/OVERTURNING EVENTS IN THE LAST WEEK HAS
RESULTED IN VERY COLD WATER TEMPS IN THE 40S DEVELOPING ALONG THE
COAST PER BUOY READINGS. THIS IS ACTUALLY RESULTING IN SOME PATCHY
FOG AS SHOWN ON THE MUSKEGON WEB CAM DESPITE A COOL AND RELATIVELY
DRY AIR MASS. SFC DEW PTS HOWEVER ARE IN THE MID 50S WHICH OVER 40
DEGREE WATER WITH WINDS 10 KTS OR LESS IS PROMOTING SOME FOG. WILL
THEREFORE ADD THIS THREAT TO THE NEARSHORE FCST OVER THE NEXT FEW
DAYS. PERIODS OF STRONGER WINDS IN THE AFTERNOON AND EARLY EVENING
MAY MIX THE FOG OUT AT TIMES.


&&

.HYDROLOGY...
ISSUED AT 330 PM EDT MON JUL 28 2014

NO HYDRO CONCERNS AT THIS TIME GIVEN ISOLATED TO SCATTERED NATURE OF
THE CONVECTION OVER THE NEXT FEW DAYS. SOME BRIEF LOCALLY HEAVY
DOWNPOURS WITH SMALL HAIL MAY OCCUR EAST OF HIGHWAY 131 AND
ESPECIALLY EAST OF U.S. 127 ON TUESDAY.

&&

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

$$

MESOSCALE UPDATE...MEADE
SYNOPSIS...NJJ
SHORT TERM...NJJ
LONG TERM...DUKE
AVIATION...LAURENS
HYDROLOGY...MEADE
MARINE...MEADE





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