Area Forecast Discussion
Issued by NWS Grand Rapids, MI

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS63 KGRR 271149
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
749 AM EDT SUN JUL 27 2014

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 328 AM EDT SUN JUL 27 2014

THUNDERSTORMS ARE LIKELY TODAY ACROSS SOUTHWEST LOWER MICHIGAN. A
FEW OF THE STORMS COULD BE STRONG TO SEVERE...ESPECIALLY SOUTHEAST
OF GRAND RAPIDS. TEMPERATURES WILL BE QUITE A BIT COOLER MONDAY AND
STRUGGLE TO REACH 70...WELL BELOW NORMAL FOR LATE JULY. HIGHS MUCH
OF NEXT WEEK WILL BE IN THE 70S.

&&

.UPDATE...
ISSUED AT 559 AM EDT SUN JUL 27 2014

ISSUING A DENSE FOG ADVISORY FOR THE SOUTHERN TWO ROWS OF COUNTIES
IN OUR CWA. FAIRLY WIDESPREAD QUARTER MILE VISIBILITIES OCCURRING
ACROSS THE SOUTH. THIS MAY NEED TO BE EXPANDED TO THE NORTH WITH
TIME. WE WILL BE KEEPING AN EYE ON HOW THE DENSE FOG EVOLVES. AT
THIS POINT FEEL MOST CONFIDENT IN THE SOUTHERN THIRD OF THE AREA.
FOG SATELLITE IMAGERY DOES SHOW THE STRATUS EXPANDING SO IT MAY
BECOME NECESSARY TO MOVE THE HEADLINE NORTH WITH TIME. FAIRLY
LIGHT WINDS AND INCREASING DEW POINTS ARE THE CULPRIT THIS
MORNING.

&&

.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 328 AM EDT SUN JUL 27 2014

FORECAST CONCERNS DEAL WITH THE CONVECTIVE THREAT TODAY.
OVERALL...OUR THINKING HASN`T CHANGED MUCH. HOWEVER...THE SPC SLIGHT
RISK HAS BEEN PUSHED SOUTH OUT OF THE CWA. THIS IS LIKELY DUE TO
SLIGHTLY LOWER SHEAR VALUES.

A COLD FRONT IS MOVING THROUGH NORTHWEST WISCONSIN ATTM. A FEW
SUPERCELLS DEVELOPED AND PRODUCED 2 INCH HAIL AS THEY MOVED THROUGH
CENTRAL WISCONSIN. THESE STORMS HAVE DIMINISHED THOUGH AS THEY`VE
OUTRUN THE STRONGER DYNAMICS.

WV IMAGERY SHOWS A WELL DEFINED SHORT WAVE MOVING OVER NORTHERN
MINNESOTA. THIS IS PUSHING THE FRONT SOUTHEAST TOWARD LOWER
MICHIGAN. AHEAD OF THE FRONT DEWPOINTS IN THE MID 60S WILL PROVIDE
PLENTY OF LOW LEVEL MOISTURE TO WORK WITH. LI`S AROUND -6C COUPLED
WITH MLCAPE VALUES AROUND 1500 J/KG WILL AND 0-6KM BULK SHEAR NEAR
40 KTS AND STRONG PVA SHOULD BE MORE THAN ENOUGH TO GENERATE SOME
ORGANIZED STORMS TODAY. FAVORED TIME FRAME IS FROM AROUND 11 AM
THROUGH 3-4 PM. FAVORED AREA IS SOUTHEAST OF GRAND RAPIDS. HIGH
LIKELY AND ABOVE POPS ARE IN THE GRIDS TODAY. CERTAINLY CAN`T RULE
OUT A SEVERE STORM OR TWO. HAIL IS THE MAIN THREAT WITH THE COLD
TEMPS ALOFT COMING IN.

THE COLD FRONT WILL QUICKLY SWEEP THROUGH THE CWA BY THIS EVENING
AND MUCH COOLER AND DRIER AIR WILL MOVE IN FOR MONDAY. HIGHS MOSTLY
IN THE UPPER 60S TO AROUND 70 EXPECTED.

A SECONDARY COLD FRONT WILL DROP SOUTH TUESDAY SO WE INCLUDED CHC
POPS FOR THAT. H5 TEMPS FALL 4C FROM MONDAY THROUGH TUESDAY. SO
LAPSE RATES STEEPEN QUITE A BIT. WOULD EXPECT SOME SMALL HAIL OUT
OF ANY STORMS THAT DEVELOP TUESDAY.

.LONG TERM...(TUESDAY NIGHT THROUGH SATURDAY)
ISSUED AT 328 AM EDT SUN JUL 27 2014

MODELS ARE STILL INDICATING AN UPPER LEVEL TROUGH OVER THE GREAT
LAKES REGION THROUGH THE BULK OF THE LONG TERM PERIOD. THE CORE OF
THE TROUGH WILL BE CENTERED OVER ONTARIO AND QUEBEC...BUT COOLER AIR
WILL SPILL INTO THE AREA. HIGH TEMPERATURES THROUGH THE PERIOD WILL
END UP BEING 5 TO 10 DEGREES BELOW NORMAL. ACTUAL HIGHS WILL RANGE
FROM THE MIDDLE TO UPPER 70S WEDNESDAY THROUGH SATURDAY.

IN TERMS OF SENSIBLE WEATHER...CONTINUED THE FORECAST THEME OF
DIURNAL SHOWERS AND A FEW STORMS. COLD AIR IN THE MID LEVELS
COMBINED WITH JULY SUNSHINE SHOULD RESULT IN AFTERNOON AND EVENING
POP UP SHOWERS AND STORMS. WEDNESDAY AND THURSDAY MAY HAVE A HIGHER
COVERAGE IN PRECIPITATION AS A MORE SUBSTANTIAL VORT LOBE IS
FORECAST TO SWING AROUND THE UPPER LOW...BRUSHING THE LOWER
PENINSULA.

CANNOT RULE OUT SOME SHOWERS AND A FEW STORMS EVEN INTO FRIDAY AND
SATURDAY AFTERNOON/S AS THE TROUGHING REMAINS IN PLACE. NOT A WASH
OUT IN THE LONG TERM BY ANY MEANS...BUT A FLARE UP IN COVERAGE EACH
DAY.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 748 AM EDT SUN JUL 27 2014

WIDESPREAD LIFR ACROSS THE AREA THIS MORNING. THE STRATUS AND FOG
SHOULD GRADUALLY LIFT THROUGH THE COURSE OF THE NEXT 3-4 HOURS OR
THROUGH 15Z TO 16Z. BY MIDDAY...EXPECTING FAIRLY WIDESPREAD MVFR
CONDITIONS. THE EXPECTATION IS THAT CONDITIONS WILL TRY TO IMPROVE
TO VFR AS WE MOVE THROUGH THE AFTERNOON AND HEAD INTO THE EVENING.
VFR WILL LIKELY BE SHORT LIVED HOWEVER AS MVFR CLOUDS SAG BACK IN
FROM THE NORTH TONIGHT BEHIND A COLD FRONTAL PASSAGE.

SCATTERED SHOWERS THIS MORNING SHOULD TURN INTO SCATTERED
THUNDERSTORMS THIS AFTERNOON. THE TIMING OF MOST PREVALENT STORMS
SHOULD BE BETWEEN 16Z AND 23Z ACROSS THE AREA. A FEW LINGERING
SHOWERS MAY REMAIN THIS EVENING BEFORE DISSIPATING OVERNIGHT.
AT THIS POINT HAVE VCTS IN FOR THIS AFTERNOON AS THE LOCATION OF
THE STORMS IS A LOW CONFIDENCE FORECAST.

&&

.MARINE...
ISSUED AT 328 AM EDT SUN JUL 27 2014

COLDER AIR WILL MOVE INTO THE REGION TONIGHT AND CONTINUE MONDAY.
THIS SURGE OF COLDER AIR WILL RESULT IN A BIG JUMP IN WAVE HEIGHTS
LATER TODAY AND TONIGHT. WE ISSUED A SCA FOR TONIGHT THROUGH MONDAY
NIGHT TO COVER THIS THREAT AND ALSO A BEACH HAZARDS STATEMENT FOR
MONDAY. THE NORTHWEST WINDS WILL CREATE LONG SHORE AND STRUCTURAL
CURRENTS THAT WILL MAKE SWIMMING HAZARDOUS...ESPECIALLY ON NORTH
SIDES OF PIERS AND BREAKWALLS.


&&

.HYDROLOGY...
ISSUED AT 1207 PM EDT SAT JUL 26 2014

THE MAIN PRECIPITATION THREAT WILL BE SUNDAY AS MOISTURE EDGES UP
INTO THE AREA. PWAT VALUES PUSH BETWEEN 1.0 TO 1.5 INCHES DURING
THE AFTERNOON. THIS MAY RESULT IN LOCALIZED HEAVY RAINFALL IN AND
AROUND THUNDERSTORMS. HOWEVER...AREA AVERAGES ARE MORE LIKELY TO
RANGE FROM ONE-QUARTER TO ONE-HALF AN INCH. PRECIPITATION THEN
SEEMS TO LINGER INTO MONDAY BUT SHOULD NOT BE OF ANY GREAT
SIGNIFICANCE IN THE MONDAY MORNING TIME FRAME.

ASIDE FROM SUNDAYS FOCUS...WE WILL SEE MAINLY DRY CONDITIONS TODAY.
ADDITIONAL CHANCES FOR LIGHT RAIN EXIST AS WE HEAD THROUGH THE NEW
WORK WEEK. NO HIGH END PRECIPITATION EVENTS ARE ANTICIPATED TO AFFECT
THE AREA. RIVERS CONTINUE TO RUN WELL BELOW ACTION STAGE...SO NO
CONCERN FOR RIVER FLOODING AT THIS TIME.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...DENSE FOG ADVISORY UNTIL 11 AM EDT THIS MORNING FOR MIZ056>059-
     064>067-071>074.

     BEACH HAZARDS STATEMENT FROM MONDAY MORNING THROUGH MONDAY
     EVENING FOR MIZ037-043-050-056-064-071.

LM...SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 6 AM EDT TUESDAY
     FOR LMZ844>849.

     DENSE FOG ADVISORY UNTIL 11 AM EDT THIS MORNING FOR LMZ844>847.

&&

$$

UPDATE...DUKE
SYNOPSIS...93
SHORT TERM...93
LONG TERM...DUKE
AVIATION...DUKE
HYDROLOGY...JAM
MARINE...93






USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.