Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 080702
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
302 AM EDT TUE JUL 8 2014

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

.SYNOPSIS...
ISSUED AT 302 AM EDT TUE JUL 8 2014

A WAVE OF LOW PRESSURE WILL MOVE THROUGH DURING THE MORNING HOURS
TODAY. THIS WILL BRING SHOWERS AND STORMS BACK INTO THE AREA THROUGH
LATE THIS MORNING. WE WILL SEE CONDITIONS DRY OUT A BIT THIS
AFTERNOON BEFORE ANOTHER LOW CHANCE OF SHOWERS DEVELOPS TONIGHT
ACROSS THE NORTH. AN ADDITIONAL CHANCE OF RAIN SHOWERS WILL COME
THROUGH ON WEDNESDAY WITH COOLER TEMPERATURES AS ANOTHER WAVE PASSES
THROUGH. THE AREA WILL DRY OUT THURSDAY AND FRIDAY ALONG WITH
INCREASING TEMPERATURES.

&&

.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 302 AM EDT TUE JUL 8 2014

THE MAIN FOCUS OF THE FCST IS ON THE THREAT FOR CONVECTION FOR
MAINLY THIS MORNING. AFTER THIS MORNING...WE WILL HAVE TO JUST
DETERMINE THE THREAT OF SOME SHOWERS THROUGH THE DAY ON WED.

WE CONTINUE TO EXPECT THAT MOST OF THE AREA WILL SEE A PERIOD OF
SHOWERS AND A FEW STORMS THROUGH THE MORNING HOURS TODAY. THE MAIN
CULPRIT IS A WAVE THAT IS DIVING SE INTO MN AND WI AS OF 07Z. THE
CONVECTION ACROSS WI IS OUT AHEAD OF THIS WAVE AND IS IN THE PROCESS
OF WEAKENING AS IT IS LOSING ITS DIURNAL INSTABILITY. WE DO EXPECT
TO SEE AN EXPANSION OF THE PCPN FIELD THROUGH 12Z AS A LLJ
STRENGTHENS OUT AHEAD OF IT AND HELPS TO RAMP UP THE MOISTURE
TRANSPORT IN OUR AREA. THIS PCPN IS THEN EXPECTED TO PUSH EAST OF
THE AREA BY 16Z OR SO.

THE THREAT FOR SEVERE WEATHER HAS DIMINISHED A BIT...BUT IS STILL
NOT ZERO ACROSS THE AREA. WITH THE PUSH OF WARM AND MOIST AIR AHEAD
OF THE WAVE...A BIT OF INSTABILITY WILL BUILD ACROSS THE
AREA...ESPECIALLY AS YOU HEAD TO THE SE. WE COULD SEE UP TO 1000
J/KG OF INSTABILITY. EFFECTIVE SHEAR IS AROUND 30-35 KNOTS...SO
THERE IS THE POTENTIAL OF SOME ORGANIZATION TO THE STORMS. FCST
SOUNDINGS INDICATE THAT A DECENT INVERSION PRESENT SHOULD LIMIT
DAMAGING WIND POTENTIAL A BIT. HAIL LOOKS TO BE THE BIGGEST THREAT.
THE BEST SEVERE THREAT WILL BE SOUTH AND EAST OF THE CWFA WHERE THE
WAVE WILL MOVE THROUGH CLOSER TO PEAK HEATING.

THE THREAT OF PCPN WILL DIMINISH A BIT THEN FOR THIS AFTERNOON AND
TONIGHT BEFORE INCREASING SOME WED. WE START TO SEE THE UPPER JET
CORE DROP INTO THE AREA LATER TODAY. THE LIMITING FACTOR FOR
ADDITIONAL SHOWERS AND STORMS POPPING UP LOOKS TO BE THE W/NW FLOW
OFF OF THE LAKE THAT WILL KEEP US A BIT STABLE. A LOW CHC OF A
SHOWER WILL REMAIN TONIGHT WHERE THE UPPER FLOW WILL BECOME CYCLONIC
OVERNIGHT. WE WILL SEE ANOTHER SHORT WAVE MOVE THROUGH EARLY WED
AFTERNOON BRINGING A THREAT OF A FEW SHOWERS. FCST SOUNDINGS
INDICATE THAT THE THREAT OF THUNDER LOOKS VERY LOW WITH THE CAP
BELOW THE ICE PRODUCING LAYERS. ANY SHOWERS WILL DIMINISH BY WED
EVENING AS THE WAVE MOVES EAST AND THE UPPER JET CORE LIFTS NE.

WE SHOULD SEE A DRY DAY ON THU. THE UPPER FLOW BECOMES ANTI-CYCLONIC
ONCE AGAIN...HOWEVER A WEAK SHORT WAVE EMBEDDED IN THE FLOW MOVES
THROUGH. DRY AIR AND BROAD SCALE SUBSIDENCE DOWNSTREAM OF THE RIDGE
AXIS SHOULD ALLOW FOR ONLY SOME MID/HIGH CLOUD COVER.

.LONG TERM...(THURSDAY NIGHT THROUGH MONDAY)
ISSUED AT 302 AM EDT TUE JUL 8 2014

COOL AND DRY WEATHER STARTS OUT THE LONG TERM PART OF THE FORECAST
BUT SLIGHTLY WARMER WEATHER WITH PERIODS OF SHOWERS AND
THUNDERSTORMS SHOULD BE EXPECTED SATURDAY INTO MONDAY.

THE IS GENERAL THERE IS DECENT AGREEMENT BETWEEN THE ECWMF AND GFS
MODELS INTO THE WEEKEND BUT BY EARLY NEXT WEEK THE ECMWF DIGS THE
UPPER LEVEL LOW FROM NORTHERN CANADA SIGNIFICANTLY FARTHER SOUTH
INTO THE GREAT LAKES REGION THAN DOES THE GFS AND IT IS
SIGNIFICANTLY DEEPER TOO. THE POLAR JET DOES NOT GET TO FAR FROM
LOWER MICHIGAN THROUGH THIS FORECAST PERIOD AND ACTUALLY WELL BEYOND
IT. SEEMS LIKE SOME SORT OF QUASI-OMAGE BLOCK SET UP WITH A CLOSED
UPPER LOW OFF THE WEST COST... AN UPPER RIDGE OVER WESTERN NORTH
AMERICA WITH A DOWN STREAM TROUGH / CLOSED UPPER LOW OVER EASTERN
CANADA INTO THE NORTHEAST CONUS. THIS SUGGESTS A NORTHERN STREAM
DOMINATED WEATHER PATTER FOR SOME TIME TO COME FOR SOUTHWEST
MICHIGAN. THE MODEL TRENDS ARE FOR MORE DIGGING OF THE UPPER LEVEL
SYSTEM EARLY NEXT WEEK. THAT TREND FAVORS THE ECMWF OVER THE GFS BUT
EITHER MODEL HAS A SIMILAR OUTCOME....THE COOLER OVERALL WEATHER
PATTERN WE HAVE HAD SO FAR IN JULY OVER THE SOUTHWEST LOWER MICHIGAN
WILL LIKELY CONTINUE WELL INTO THE FOLLOWING WEEK.

THE SYSTEM THAT COMES THROUGH THE GREAT LAKES THIS COMING WEEKEND IS
COMPLEX AS IT IS A INTERACTION BETWEEN THE DIGGING NORTHERN STREAM
SYSTEM AND SOUTHERN STREAM SHORTWAVE ENERGY RIDING OVER THE TOP OF
THE UPPER RIDGE. THIS SUGGESTS SOME SORT OF STATIONARY FRONT WITH
WAVES ON IT. I WOULD IMAGINE THIS COMING WEEKEND WILL BE RATHER WET
WITH PERIODS OF SHOWERS AND THUNDERSTORMS UNTIL THAT NORTHERN STREAM
UPPER LOW FINALLY DIGS INTO THE GREAT LAKE EARLY NEXT WEEK (MONDAY
AND BEYOND).

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1230 AM EDT TUE JUL 8 2014

AN AREA OF SHOWERS AND EMBEDDED THUNDERSTORMS WILL MOVE THROUGH
THE TAF SITES BETWEEN 07Z AND 15Z OR SO. THEY WILL AFFECT KMKG
FIRST AND EXIT EAST OF KLAN AND KJXN AROUND 15Z-16Z. THE SHOWERS
AND STORMS WILL LIKELY HAVE VFR BASES FOR THE MOST PART THAT MAY
DIP LOWER BRIEFLY IN THE HEAVIER SHOWERS. MVFR VISIBILITIES LOOK
LIKELY AS THE PRECIPITATION ROLLS THROUGH.

THERE IS SOME INDICATION THAT THERE MAY BE A BIT OF FOG/STRATUS
AROUND THEN IN THE WAKE OF THE SHOWERS BETWEEN 10Z-14Z...BUT DID
NOT INCLUDE THIS IN THE TAFS AS IT IS LOW CONFIDENCE.

CONDITIONS SHOULD BE VFR AHEAD OF THE SHOWERS/STORMS OVERNIGHT AND
THEN AGAIN IN THE WAKE OF THE ACTIVITY TUESDAY AFTERNOON/EVENING.

THE WINDS WILL PICK UP TUESDAY MIDDAY AND AFTERNOON OUT OF THE
WEST...BECOMING GUSTY IN THE 15-25 KNOT RANGE. WINDS WILL TAPER
BACK AFTER 00Z TOMORROW EVENING.


&&

.MARINE...
ISSUED AT 302 AM EDT TUE JUL 8 2014

NO MARINE HEADLINES ARE NEEDED WITH THIS FCST PACKAGE. WINDS WILL
INCREASE A BIT TODAY IN THE WAKE OF THE WAVE OF LOW PRESSURE MOVING
THROUGH THIS MORNING. WINDS ARE FCST TO INCREASE UP TO ABOUT 20
KNOTS FOR A PERIOD LATE THIS MORNING AND EARLY THIS AFTERNOON. WE
EXPECT THAT WAVES UP TO 2 TO 4 FEET CAN BE EXPECTED FOR A PERIOD
BEFORE COMING BACK DOWN. WE WILL SEE WINDS DROP OFF LATER TODAY AND
TONIGHT BEFORE INCREASING A BIT AGAIN ON WED AFTERNOON BEHIND
ANOTHER WAVE PASSING THROUGH.

&&

.HYDROLOGY...
ISSUED AT 1220 PM EDT MON JUL 7 2014

EXCESSIVE RAINFALL OVERNIGHT IN THE HARDEST HIT AREAS RANGED FROM
2 TO 6 INCHES. THIS HAS LED TO ROAD WASHOUTS AND CLOSURES WITH A
FEW RISING RIVERS AND STREAMS. TRAVEL MAY CONTINUE TO BE IMPACTED
THROUGH EARLY MONDAY EVENING ACROSS IONIA...MONTCALM...AND GRATIOT
COUNTIES WHERE THERE IS STANDING WATER. ADDITIONAL RAINFALL
OVERNIGHT IS NOT EXPECTED TO AMOUNT TO MORE THAN A HALF INCH OR SO
ON AVERAGE. LOCALIZED HIGHER AMOUNTS ARE POSSIBLE BUT OVERALL WE
ARE NOT EXPECTING SIGNIFICANT HYDROLOGIC ISSUES OVERNIGHT AND INTO
TUESDAY.

AS FOR THE RIVERS AND STREAMS...OUR MAIN CONCERN RESIDES WITH THE
PINE RIVER AT ALMA (JUST UNDER 5" OF RECORDED RAIN THERE). A RIVER
FLOOD WARNING IS IN EFFECT FOR MINOR FLOODING THROUGH LATE TUESDAY
NIGHT. RISES ON THE GRAND ARE EXPECTED WITH BANKFULL BEING
EXCEEDED AT IONIA. RISES ON THE MAPLE RIVER WILL ALSO SEND THE
RIVER ABOVE BANKFULL AT MAPLE RAPIDS. WE`LL ALSO NEED TO MONITOR
THE LOOKING GLASS RIVER AT EAGLE FOR READINGS NEAR BANKFULL. HIGH
LEVELS WILL CONTINUE ON THESE RIVERS FOR THE NEXT FEW DAYS.

&&

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

$$

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




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