Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 241927
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
327 PM EDT FRI OCT 24 2014

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

.SYNOPSIS...
ISSUED AT 327 PM EDT FRI OCT 24 2014

A WEAK FRONTAL SYSTEM WILL MOVE THROUGH THE AREA LATER TONIGHT AND
DURING THE FIRST HALF OF THE DAY ON SATURDAY. THIS FRONT WILL BRING
MORE CLOUDS IN TONIGHT AND A CHANCE OF SPRINKLES AFTER A BRIEF
PERIOD OF CLEARING LATE THIS AFTERNOON AND THIS EVENING. CLOUDS WILL
MOVE OUT DURING THE DAY ON SATURDAY AND MILD TEMPERATURES WILL
REMAIN.

THE NEXT WEATHER MAKER WILL START TO MAKE ITS WAY IN ON SUNDAY NIGHT
AND EARLY ON MONDAY. SHOWERS AND POSSIBLE STORMS WILL MOVE IN SUNDAY
NIGHT AS ANOTHER SURGE OF WARM AIR MOVES UP INTO THE AREA. MORE RAIN
WILL MOVE IN FOR MONDAY NIGHT AND TUESDAY.

&&

.SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT)
ISSUED AT 327 PM EDT FRI OCT 24 2014

NO MAJOR WEATHER IS EXPECTED THROUGH THE SHORT TERM PORTION OF THE
FCST. CLOUD TRENDS AND THE THREAT OF RAIN TONIGHT WILL BE THE FIRST
FOCUS...THEN TRANSITIONING TO SHOWERS AND POSSIBLE STORMS FOR SUNDAY
NIGHT.

WE ARE STILL EXPECTING A BRIEF WINDOW OF PARTIAL CLEARING TO TAKE
PLACE LATE THIS AFTERNOON AND EVENING ACROSS THE AREA. RESIDUAL LOW
LEVEL MOISTURE WITH THE WEAKENING FRONT HAS HELD OVER THE AREA
THROUGH EARLY THIS AFTERNOON. MORE BREAKS ARE OPENING UP...AND WE
EXPECT THESE TO EXPAND AS THE LOW CLOUDS DISSIPATE AND MOVE OUT.

WE HAVE ADDED A CHANCE OF SPRINKLES TO THE FCST FOR TONIGHT AND
EARLY SAT WITH THE FRONTAL PASSAGE. CLOUDS WILL MOVE BACK IN
OVERNIGHT WITH THE APPROACH OF THE NEXT FRONT CURRENTLY ACROSS THE
MO RIVER AS OF 19Z. THERE IS LESS IN THE WAY OF UPPER SUPPORT WITH
THIS NEXT FRONT COMPARED TO LAST NIGHT/S FRONT. SHORT WAVE ENERGY
AND UPPER JET SUPPORT BOTH STAY WELL NORTH OF THE AREA. WEAK LL
MOISTURE TRANSPORT WILL BE WORKING ON A MORE MOIST ATMOSPHERE
COMPARED TO YESTERDAY. WE DO NOT EXPECT MEASURABLE PCPN TONIGHT OR
SAT MORNING.

THE FRONT SHOULD BEGIN TO MOVE THROUGH THE AREA AROUND 12Z SAT...AND
SHOULD EXIT THE CWFA BY ABOUT 20Z OR SO. SHORTLY BEHIND THE
FRONT...THE LOWER CLOUD COVER SHOULD CLEAR OUT AND TEMPS SHOULD
SNEAK INTO THE 60S AS BEST CAA DOES NOT TAKE PLACE UNTIL SAT NIGHT.
WE EXPECT MAINLY CLEAR SKIES THEN THROUGH SUN EVENING.

RAIN CHANCES WILL MOVE BACK IN ACROSS THE NW HALF OF THE CWFA LATE
ON SUN NIGHT. THE STRONG SYSTEM OFF OF THE PACIFIC NW TODAY WILL
OPEN UP A BIT AND TRANSLATE ACROSS THE ROCKIES INTO THE PLAINS BY
SUN NIGHT. THIS WILL HELP TO STRENGTHEN A WARM FRONT TO OUR SW AND
DRIVE IT IN HERE LATE SUN NIGHT. A DECENT SURGE OF WARMTH AND
MOISTURE ALOFT WILL HELP TO DEVELOP SHOWERS ACROSS THE NW. THUNDER
WILL BE POSSIBLE WITH ELEVATED LI/S GOING NEGATIVE OVER THE AREA.

.LONG TERM...(MONDAY THROUGH FRIDAY)
ISSUED AT 327 PM EDT FRI OCT 24 2014

THIS PERIOD IS ONE OF SIGNIFICANT CHANGES FROM THE START OF THE
FORECAST ON MONDAY TO THE END OF THE FORECAST ON HALLOWEEN. A STRONG
PACIFIC SYSTEM WILL BRING SHOWERS AND THUNDERSTORMS TO THE AREA
MONDAY INTO TUESDAY. THEN WE GET A GOOD SHOT OF COLD AIR BEHIND THE
SYSTEM FOR WEDNESDAY ONLY TO HAVE A DIGGING NORTHERN STREAM WAVE
BRING THE POTENTIAL FOR AN EVEN STRONGER COLD FRONT IN THE THURSDAY
TO FRIDAY TIME FRAME.

THE REMNANTS OF EXTRATROPICAL LOW ASSOCIATED WITH CURRENT PACIFIC
TROPICAL STORM ANA NOW LOCATED WELL NW OF THE HAWAIIAN ISLANDS
MERGES WITH THE PACIFIC SYSTEM  MOVING ON SHORE FROM THE GULF OF
ALASKA. TYPICALLY THE MODELS UNDERPLAY THESE SORTS OF SYSTEMS SO I
WOULD IMAGINE WHAT WE WILL ACTUALLY SEE WILL BE STRONGER AND SLOWER
THEN THE MODELS CURRENTLY SHOW. THAT FAVORS THE LOWER ECMWF SO I
HAVE THE BEST CHANCE FOR PRECIPITATION ON TUESDAY. ALSO THERE IS
DECENT INSTABILITY (850 LI NEGATIVE) AND THE LOW LEVEL JET OF 40
KNOTS AT 12Z NEAR SBN INCREASES TO NEAR 50 KNOTS BY DTW BY TUESDAY
EVENING. WHEN WE ADD THE ENTRANCE REGION TO A 100 KNOT 300 MB JET TO
THE PICTURE AND NEAR NEGATIVE TILT UPPER TROUGH... I HAVE TO BELIEVE
THUNDERSTORMS ARE MORE THAN POSSIBLE TUESDAY.  I PUT LIKELY POPS FOR
THIS.

THAT SYSTEM TAPS SOME COLD AIR SO WE WOULD GET SOME LAKE EFFECT
SHOWERS WEDNESDAY. THE REAL ISSUE IS THURSDAY INTO FRIDAY. HERE WE
HAVE 130 TO 140 KNOT JET DIVING INTO THE ALREADY CREATED EASTERN
TROUGH. HOW THIS PLAYS OUT DEPEND ON WHAT HAPPENS TO THE UPSTREAM
SYSTEM OVER THE GULF OF ALASKA.  GIVEN THE MUCH WARMER THAN NORMAL
WATERS OFF THE COAST OF SOUTHERN ALASKA AND WEST OF BRITISH
COLUMBIA... I AM THINKING THAT SYSTEM WILL BE FARTHER WEST AND
DEEPER SO THE UPSTREAM RIDGE WILL BE BIGGER AND THERE WILL BE MORE
DIGGING INTO THE GREAT LAKES WITH THIS NEXT SYSTEM FOR THURSDAY INTO
FRIDAY. THIS SHOULD BE THE COLDEST WEATHER BY FAR FOR THIS SEASON SO
FAR. I DID NOT PUT SNOW IN THE GRIDS YET BUT DO NOT BE SURPRISED IF
SNOW STARTS SHOWING UP THE GRIDS FOR HALLOWEEN.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 327 PM EDT FRI OCT 24 2014

THE LOW CLOUDS SHOULD CLEAR OUT BY LATE AFTERNOON ONLY TO
REDEVELOP BY MIDNIGHT OR SO.

THE PRIMARY ISSUE IS WHAT HAPPENS TO THE IFR CIGS NORTH AND WEST
OF MKG (OVER EASTERN WISCONSIN...LAKE MICHIGAN... AND NORTHWEST
LOWER MICHIGAN) OVER THE NEXT FEW HOURS. LOOKING AT THE VISIBLE
SATELLITE LOOPS IT SEEMS THE CLEARING IS WORKING NORTHWARD OVER
THE PAST FEW HOURS. THAT TREND GOES ALONG WITH BOTH THE RAP AND NAM
950 TO 850 MB RH FORECAST WHICH ALSO SHOWS CLEARING OF LOW CLOUDS.
BY LATE AFTERNOON MOST LOCATIONS. SO THAT IS WHAT I DID WITH THE
TAF FORECAST FOR THIS AFTERNOON.

THE NEXT ISSUE IS FOG/STRATUS TONIGHT. THE NAMDNG5...WHICH I HAVE
NOTED DOES VERY NICELY WITH FORECASTING FOG AND FOR THAT MATTER
SO DOES THE RAP13...BOTH SHOW NEARLY THE ENTIRE CWA GOING DOWN IN
FOG BY 09Z. THE PROBLEM THERE THOUGH IS THERE IS 15 TO 20 KNOTS OF
WIND IN THE BOUNDARY LAYER. THAT WOULD SUGGEST TO ME A STRATUS
DECK IS MORE LIKELY. SO MY TAFS SHOW CLEARING BY LATE AFTERNOON
THEN I BRING THE FOG AND LOW CLOUDS BACK LATE TONIGHT. FOR THE MOST
PART THE LOW CLOUDS WILL BE SLOW TO MIX OUT SATURDAY.


&&

.MARINE...
ISSUED AT 327 PM EDT FRI OCT 24 2014

WE CONTINUE TO FOCUS ON THE POTENTIAL SMALL CRAFT ADVISORY EVENT FOR
LATE SAT AND SAT NIGHT. SW WINDS WILL SLOWLY INCREASE TONIGHT AND
DURING THE FIRST HALF OF SAT. WINDS WILL INCREASE UP TO ABOUT 20
KNOTS BY THEN IN THE FLOW AHEAD OF THE NEXT FRONT COMING THROUGH. WE
WILL SEE A BETTER CHC OF ADVISORY CONDITIONS ON SAT AFTERNOON AND
NIGHT BEHIND THE FRONT AS COOLER AIR MOVES IN. IT IS LOOKING LIKELY
WE WILL SEE WINDS AND WAVES HIT CRITERIA THROUGH SAT NIGHT BEFORE
COMING DOWN ON SUN.

IT LOOKS LIKE WINDS WILL INCREASE ONCE AGAIN ON MON AND REMAIN UP
THROUGH THE FIRST HALF OF THE WEEK. ADVISORIES WILL BE LIKELY AT
THAT TIME ALSO.

&&

.HYDROLOGY...
ISSUED AT 327 PM EDT FRI OCT 24 2014

NO HYDROLOGY ISSUES ARE EXPECTED OVER THE NEXT WEEK. RIVER LEVELS
ARE STARTING OUT AROUND AVERAGE WITH THE RECENT DRY WEATHER WE HAVE
HAD. WE ARE NOT EXPECTING ANY MEASURABLE PCPN UNTIL AT LEAST SUN
NIGHT.

THERE WILL BE A COUPLE OF PERIODS OF RAIN NEXT WEEK. EACH OF THESE
RAIN EVENTS LOOK TO BE ON THE LIGHTER SIDE WITH ONLY A QUARTER TO
HALF AN INCH OF RAIN WITH EACH EVENT. THESE AMOUNTS SPREAD OUT OVER
THE WEEK WILL NOT CAUSE ANY MAJOR RISES ON THE AREA RIVERS.

&&

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

$$

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





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