Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 241427
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1027 AM EDT FRI APR 24 2015

LATEST UPDATE...
HYDRO

.SYNOPSIS...
ISSUED AT 328 AM EDT FRI APR 24 2015

THE AREA WILL SEE QUITE A BIT MORE SUNSHINE AND MILDER TEMPERATURES
TODAY COMPARED TO THE LAST FEW DAYS OF COLD AND UNSETTLED WEATHER.
HIGH PRESSURE WILL BE IN CONTROL TODAY. A SYSTEM COMING IN FROM THE
SOUTHWEST WILL TRY AND BRING SOME RAIN TO THE AREA LATE TONIGHT
THROUGH THE DAY ON SATURDAY. THE CHANCE OF RAIN WILL GENERALLY STAY
SOUTH OF I-96...WITH MOST RAIN OCCURRING ALONG AND SOUTH OF I-94.

THE AREA SHOULD SEE SUNSHINE RETURN ON SUNDAY WITH SEASONABLE
TEMPERATURES. GENERALLY DRY WEATHER LOOKS TO BE POSSIBLE FOR THE
FIRST HALF OF NEXT WEEK.

&&

.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 328 AM EDT FRI APR 24 2015

OUR ONE AND ONLY WEATHER FEATURE IN THE SHORT TERM IS THE POTENTIAL
OF SOME RAIN FROM LATE TONIGHT INTO SATURDAY EVENING FOR MAINLY THE
SRN HALF OF THE CWFA. THE FCST THIS MORNING HAS TIGHTENED THE
GRADIENT OF RAIN CHCS UP A BIT...RESULTING IN DROPPING RAIN CHCS UP
NORTH.

NO WORRY ABOUT RAIN CHCS TODAY. WE WILL BE DOWNSTREAM OF UPPER
RIDGING TO OUR WEST TODAY...WITH SFC RIDGING OVERHEAD. WE WILL START
OUT WITH QUITE A DRY AIR MASS IN PLACE...SO SOME MID/HIGH LEVEL
MOISTURE WILL ONLY BRING SOME THIN CLOUDS TO THE AREA.

SOME RAIN CHCS WILL TRY TO DEVELOP OVERNIGHT TONIGHT ACROSS THE FAR
SW CORNER OF THE CWFA. RAIN OCCURRING TO OUR WEST AND SOUTHWEST WILL
TRY MOVING INTO THE AREA AS RETURN FLOW SETS UP OUT AHEAD OF AN
INCOMING LOW FROM THE ROCKIES AND SRN PLAINS STATES. MOST OF THE
MODELS DO NOT QUITE BRING THE GOOD MOISTURE RETURN/TRANSPORT INTO
THE AREA. RAIN THAT TRIES TO MOVE IN WILL ENCOUNTER A DRY AIR
MASS...SO MUCH OF IT WILL EVAPORATE.

THERE WILL BE A SECOND PUSH OF RAIN THAT TRIES TO COME IN DURING THE
DAY ON SATURDAY. THIS OCCURS AS AN UPPER LOW LIFTS E/NE OUT OF THE
PLAINS STATES. THIS LOW WOULD NORMALLY MAKE IT INTO THE AREA AND
GIVE THE AREA A NICE SOAKING. HOWEVER AS IT IS MOVING TOWARD THE
AREA...A NRN STREAM TROUGH WILL DROP SOUTH OUT OF CANADA AND SHUNT
THE LOW TO OUR SOUTH. MOST OF THE MODELS HAVE BEEN CONSISTENT IN
BRINGING RAIN UP INTO THE SRN THIRD OF THE CWFA BEFORE IT WOULD STOP
AND THEN PUSH SE. A GOOD FEED OF DRY AIR COMING IN FROM THE E/NE
WILL ALSO EAT AWAY AT LIGHT RAIN ON THE NRN EDGE OF THE PCPN
SHIELD...AND CREATE A SHARP CUTOFF TO THE RAIN.

THE RAIN WILL THEN PULL ENTIRELY AWAY FROM THE AREA SAT EVENING AS
THE NRN TROUGH PUSHES THROUGH. NRLY FLOW WILL THEN DOMINATE WITH
COOL AND DRY AIR MOVING INTO THE AREA ON SUN. MOISTURE WILL BE
LACKING ON SUN...OTHERWISE SOME CHCS FOR RAIN SHOWERS WOULD BE
NEEDED WITH ANOTHER TROUGH MOVING THROUGH.

.LONG TERM...(SUNDAY NIGHT THROUGH THURSDAY)
ISSUED AT 328 AM EDT FRI APR 24 2015

LONG TERM PERIOD CONTINUES TO LOOK UNEVENTFUL. GFS AND THE ECMWF
OPERATIONAL 00Z RUNS CONTINUE TO HAVE SOME DIFFERENCES IN THE
HANDLING OF THE UPPER PATTERN. THE GFS BRINGS IN A DEEP UPPER LOW
FOR THE MIDDLE TO END OF THE WEEK WHERE THE ECMWF IS MORE
PROGRESSIVE WITH MUCH LESS TROUGHING. HAVE CONTINUED TO SIDE WITH
THE ECMWF.

HAVE A DRY FORECAST THROUGH THE ENTIRE LONG TERM...AS HIGH PRESSURE
IS FORECAST TO PREVAIL THE BULK OF THE TIME. BOTH MODELS INDICATE
LIMITED MOISTURE OVER ANY SIZABLE DEPTH. FEEL FAIRLY CONFIDENT IN
THE DRY FORECAST GIVEN THAT FACT. WEDNESDAY AND WEDNESDAY NIGHT
WOULD BE THE TWO FORECAST PERIODS THAT I COULD SEE POTENTIALLY
MENTIONING SOME LIGHT RAIN...GIVEN A WEAKENING UPPER WAVE DIVING OUR
DIRECTION IN NORTHWEST UPPER FLOW. ECWMF 1000-700MB RH SHOWS
MOISTURE DRYING UP AS IT MOVES INTO THE GREAT LAKES REGION.

REGARDING TEMPERATURES...850MB TEMPS ARE FORECAST VIA THE ECMWF TO
BE IN THE 0 TO +6C RANGE MUCH OF THE TIME WHICH SHOULD YIELD
SEASONABLE READINGS. HIGH TEMPS SHOULD MODERATE A BIT AS WE MOVE
THROUGH THE PERIOD...WITH LOW 60S COMMON NEXT WEEK.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 722 AM EDT FRI APR 24 2015

VFR WEATHER IS EXPECTED THE NEXT 24 HOURS. MID CLOUDS WITH BASES
ABOVE 10000FT WILL SPREAD INTO THE AREA FROM THE WEST THIS
MORNING...LOWERING TO AROUND 8000FT THIS AFTERNOON AND EVENING.
TONIGHT...CEILINGS SHOULD LOWER SLIGHTLY INTO THE 4000-7000FT
RANGE.

WINDS WILL GENERALLY BE LIGHT UNDER 10 KNOTS THROUGH THE
PERIOD. SOME RAIN SHOWERS WILL SPREAD INTO THE SOUTHWEST CORNER OF
THE STATE LATE TONIGHT...AFFECTING KAZO AND KBTL. AT THIS POINT
USED VCSH WORDING AS TIMING IS STILL A BIT UNCERTAIN.

&&

.MARINE...
ISSUED AT 328 AM EDT FRI APR 24 2015

WE ANTICIPATE THAT NO MARINE HEADLINES WILL BE NEEDED THROUGH THE
COMING WEEKEND. WINDS WILL BE RATHER LIGHT TODAY WITH HIGH PRESSURE
MOVING OVERHEAD. WINDS WILL THEN START TO INCREASE LATER TONIGHT AND
REMAIN SOMEWHAT ELEVATED THROUGH SUNDAY WITH THE NEXT SYSTEM MOVING
THROUGH ON SATURDAY...AND THEN BEHIND IT ON SUNDAY. WE BELIEVE THAT
WINDS WILL BE GENERALLY 10 TO 20 KNOTS WITH WAVES UP TO 4 FT.

&&

.HYDROLOGY...
ISSUED AT 1027 AM EDT FRI APR 24 2015

RIVER LEVELS ACROSS SOUTHWEST LOWER MICHIGAN ARE STEADY OR SLOWLY
FALLING. RAIN IS POSSIBLE ACROSS SOUTHERN LOWER MICHIGAN SOUTH OF
INTERSTATE 96 LATE TONIGHT INTO SATURDAY NIGHT. ACCUMULATIONS SHOULD
BE UNDER A HALF INCH. DRY WEATHER RETURNS LATE SATURDAY NIGHT
THROUGH NEXT WEEK. BRIEF RISES ARE POSSIBLE ON THE SOUTHERN
RIVERS... BUT RIVER FLOODING IS NOT EXPECTED.

&&

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

&&

$$

SYNOPSIS...NJJ
SHORT TERM...NJJ
LONG TERM...DUKE
AVIATION...DUKE
HYDROLOGY...63
MARINE...NJJ





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