Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 151924
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
325 PM EDT MON SEP 15 2014

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

.SYNOPSIS...
ISSUED AT 325 PM EDT MON SEP 15 2014

AFTER RAIN EXITS THE AREA THIS EVENING...HIGH TEMPERATURES IN THE
MID 60S TUESDAY WILL GRADUALLY WARM INTO THE MID 70S BY SATURDAY.
DRY AND COOL OVERNIGHT CONDITIONS MAY ALLOW PATCHY FROST TO DEVELOP
WEDNESDAY NIGHT OVER CENTRAL LOWER MICHIGAN. SHOWERS AND
THUNDERSTORMS WILL BE POSSIBLE BEGINNING LATE FRIDAY.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT)
ISSUED AT 325 PM EDT MON SEP 15 2014

MAIN CHALLENGE IN SHORT TERM IS TIMING THE EXIT OF RAIN...MOST OF
WHICH IS BEHIND THE SURFACE COLD FRONT CURRENTLY MOVING ACROSS THE
NORTHWEST FORECAST AREA. PRECIPITATION AMOUNTS UPSTREAM OVER
WISCONSIN HAVE NOT BEEN IMPRESSIVE - ONLY A FEW HUNDREDTHS IN SPOTS.
COVERAGE HOWEVER IS INCREASING AND EXPECT THIS TO CONTINUE IN THE
SHORT TERM. EXPECT A RAPID EXIT OF PRECIPITATION TO THE SOUTHEAST
THIS EVENING AND EARLY TONIGHT.

ADDED PATCHY FROST WEDNESDAY NIGHT FOR INTERIOR PORTIONS OF NORTH
CENTRAL MICHIGAN. SURFACE HIGH PRESSURE CENTERED OVER THE AREA WILL
BE FAVORABLE FOR RADIATIONAL COOLING...BUT THIS COULD BE OFFSET BY
SOME LOW CLOUDINESS. THANKS APX FOR COORDINATION.


.LONG TERM...(THURSDAY THROUGH MONDAY)
ISSUED AT 325 PM EDT MON SEP 15 2014

THE PRIMARY FOCUS IS ON SHOWER AND TSTM POTENTIAL OVER THE WEEKEND
AND HOW WARM IT GETS.

STRONG WARM ADVECTION KICKS IN ON FRIDAY NIGHT IN RESPONSE TO THE
DIGGING H5 WAVE OVER THE NRN PLAINS. BEST FORCING IS CURRENTLY
PROGGED TO BE ACROSS UPR MI AND NRN LWR MI ON THE NOSE OF THE LOW
LEVEL JET... BUT CHANCE POPS ARE WARRANTED IN SW LWR MI AS THE WARM
FRONT LIFTS THROUGH.

WE SHOULD BE FIRMLY IN THE WARM SECTOR ON SATURDAY WITH MOST OF THE
CONVECTION TO OUR NORTH AND WEST. H8 TEMPS AROUND 15C AND DECENT
MIXING MAY ALLOW FOR HIGHS TOUCHING 80 DEGREES INLAND FROM LAKE
MICHIGAN. HOWEVER A FASTER COLD FRONT SOLUTION AND EARLIER ARRIVAL
OF CLOUDS/SHOWERS COULD MAKE IT DIFFICULT TO GET THAT WARM.

CURRENTLY THE SFC COLD FRONT/SHORTWAVE PASSAGE AND BEST CHANCE OF
RAIN IS PROGGED FOR SATURDAY NIGHT... FOLLOWED BY A COOL DOWN ON
SUNDAY AND MONDAY. THE NEW 12Z RUN OF THE ECMWF IS VERY AGGRESSIVE
WITH THE COLD ADVECTION NEXT MONDAY... SHOWING H8 TEMPS LESS THAN
ZERO INVADING THE STATE. THIS WOULD RESULT IN MORE IN THE WAY OF
CLOUDS AND A CHANCE OF LAKE EFFECT RAIN SHOWERS WHICH IS NOT
CURRENTLY IN THE FCST. IF THIS MODEL TREND CONTINUES THEN FUTURE
FORECASTS FOR A WEEK FROM NOW WILL NEED TO BE TRENDED MORE
PESSIMISTICALLY.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 159 PM EDT MON SEP 15 2014

RAIN HAS HAD A HARD TIME DEVELOPING OVER THE TAF SITES TODAY AS
WE ARE IN A DRY SLOT IN BETWEEN RAIN AREAS TO THE NORTH AND SOUTH.
CONDITIONS ARE STILL VFR AT 18Z... WITH ANY MVFR LOOKING LIKE IT
WILL HOLD OFF UNTIL AFTER 22Z AND WILL BE PRIMARILY AT THE
AZO/BTL/JXN TAF SITES FOR A FEW HOURS THIS EVENING.

CLEARING/IMPROVEMENT IS STILL EXPECTED LATER THIS EVENING/OVERNIGHT
FROM NORTHWEST TO SOUTHEAST... ALTHOUGH SOME MVFR FOG COULD
DEVELOP IN SPOTS AFTER IT CLEARS. WOULD NOT EVEN RULE OUT THE
POSSIBILITY OF IFR STRATUS/FOG DEVELOPING AFTER 06Z TONIGHT DUE TO
LIGHT WINDS AND MOIST BOUNDARY LAYER...BUT NOT CONFIDENT ENOUGH
YET TO INTRODUCE THOSE LOWER CONDITIONS INTO THE TAFS. IT IS
SOMETHING TO MONITOR FOR FUTURE UPDATES THOUGH.

&&

.MARINE...
ISSUED AT 325 PM EDT MON SEP 15 2014

NO HEADLINES ARE EXPECTED. THERE WILL BE A BRIEF UPTICK IN WAVES
OVERNIGHT WITH A SURGE OF WIND BEHIND THE COLD FRONT PASSING
THROUGH...BUT THEY SHOULD GENERALLY STAY WELL BELOW 4 FEET.

&&

.HYDROLOGY...
ISSUED AT 325 PM EDT MON SEP 15 2014

RIVERS CONTINUE RUNNING NEAR TO ABOVE NORMAL FOR MID SEPTEMBER.
SEVERAL DRY DAYS THIS WEEK WILL ENSURE THIS TREND CONTINUES. BY LATE
IN THE WEEK AND WEEKEND THERE WILL BE A THREAT FOR SHOWERS AND
THUNDERSTORMS AS A FRONT APPROACHES. IT IS TOO EARLY TO TELL HOW
MUCH RAINFALL IS POSSIBLE WITH THIS SYSTEM BUT SIGNIFICANT AMOUNTS
ARE NOT OUT OF THE QUESTION IF THE FRONT MOVES SLOWER AND ALSO
DEPENDING ON WHERE THE REMNANTS OF HURRICANE ODILE MOVE. A CLEARER
PICTURE WILL HOPEFULLY EVOLVE OVER THE NEXT COUPLE DAYS.

&&

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

&&

$$

SYNOPSIS...TJT
SHORT TERM...TJT
LONG TERM...MEADE
AVIATION...MEADE
HYDROLOGY...HOVING
MARINE...TJT





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