Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 171600
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1200 PM EDT FRI APR 17 2015

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 318 AM EDT FRI APR 17 2015

MOSTLY SUNNY AND MILD WEATHER IS EXPECTED TODAY AND SATURDAY.
TEMPERATURES WILL CLIMB INTO THE 70S BOTH DAYS. SHOWERS WILL DEVELOP
SUNDAY AS LOW PRESSURE MOVES OVER THE GREAT LAKES. AS THE LOW MOVES
BY COLDER AIR WILL FLOW IN BEHIND IT. NEXT WEEK WILL BE RATHER
CHILLY WITH HIGHS IN THE 40S AND 50S AND A BRISK NORTHEAST WIND.

&&

.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 318 AM EDT FRI APR 17 2015

FORECAST CONCERNS DEAL WITH PCPN POTENTIAL SUNDAY. THE SHORT RANGE
MODELS CONTINUE TO BE FAIRLY BULLISH ON RAIN SUNDAY. IF THE NORTHERN
AND SOUTHERN STREAMS BOTH PHASE AS IS ADVERTISED BY BOTH THE ECMWF
AND GFS...WE/LL SEE A STRONG UPPER WAVE OVER SOUTHERN CANADA KICK
OUT THE ROCKIES LOW INTO THE PLAINS AND BEGIN TO PICK IT UP AS THEY
TRAVEL IN TANDEM EASTWARD. STRONG SOUTHERLY FLOW WILL DEVELOP AHEAD
OF IT AS THE RIDGE OVER THE GREAT LAKES MOVES EAST. THAT SOUTH FLOW
WILL DRAW UP ABUNDANT MOISTURE FROM THE GULF. AS THE PHASED SFC LOW
DEVELOPS OVER ILLINOIS RAIN WILL EXPAND OVER THE CENTRAL LAKES
SOMETIME SUNDAY MORNING AND CONTINUE THROUGH THE DAY.
SUNDAY...ESPECIALLY EARLY IN THE DAY COULD BE RATHER BREEZY AND THE
GRADIENT TIGHTENS. QPF AROUND A QUARTER INCH SEEMS PLAUSIBLE. WE
KEPT THUNDER OUT OF THE GRIDS AS ELEVATED INSTABILITY IS A BIT
LACKING AND THERE WERE MIXED SIGNALS AS TO WHETHER THETA-E WAS
DECREASING WITH HEIGHT.

THE NEXT TWO DAYS LOOK NICE IF YOU LIKE WARM WEATHER. RIDGING
OVERHEAD WILL PROVIDE PLENTY OF SUNSHINE AS TEMPERATURES CLIMB INTO
THE 70S.

.LONG TERM...(SUNDAY NIGHT THROUGH THURSDAY)
ISSUED AT 318 AM EDT FRI APR 17 2015

MODEL GUIDANCE REMAINS CONSISTENT IN SHOWING RAIN LIKELY SUNDAY
NIGHT AND MONDAY AS A SFC LOW AND UPPER TROUGH AXIS MOVES OVER LOWER
MICHIGAN. THE LOW CUTS OFF AND BECOMES VERTICALLY STACKED OVER LAKE
SUPERIOR ON MONDAY WITH VORT ENERGY ROTATING THROUGH LOWER MICHIGAN
ON TUESDAY AND WEDNESDAY. FAIR WEATHER RETURNS THURSDAY AS THE LOW
LIFTS OUT AND SFC RIDGING BUILDS IN.

GIVEN WET BULB ZERO HEIGHTS CRASHING TO NEAR THE SFC...DO NOT BE
SURPRISED TO SEE SOME SNOW AT TIMES TUESDAY THROUGH WEDNESDAY AND
SOME LIGHT ACCUMS ARE EVEN POSSIBLE ACROSS THE HIGH GROUND OF THE
NORTHERN ZONES.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY)
ISSUED AT 1200 PM EDT FRI APR 17 2015

VFR CONDITIONS WILL CONTINUE THROUGH 18Z SATURDAY. WEST WINDS AOB 10
KTS THIS AFTERNOON WILL SUBSIDE TO 5 KTS OR LESS TONIGHT BEFORE
BECOMING NORTHEASTERLY AND INCREASING TO AROUND 10 KTS BY MID TO
LATE SATURDAY MORNING.

&&

.MARINE...
ISSUED AT 318 AM EDT FRI APR 17 2015

SOUTHWEST WINDS 5 TO 15 KNOTS WILL NOT POSE A THREAT TO SMALL CRAFT
TODAY.


&&

.HYDROLOGY...
ISSUED AT 1119 AM EDT FRI APR 17 2015

NO RIVER FLOOD ADVISORIES ARE IN EFFECT AT THIS TIME. IMPROVEMENT
IS EXPECTED TO CONTINUE AS DRY CONDITIONS WILL HOLD STRONG TODAY
THROUGH SATURDAY.

THOUGHTS ON THE NEXT ROUND OF MOISTURE ARE CONSISTENT WITH THE
PREVIOUS HYDRO UPDATE (4/16). A DECENT SOAKING RAIN IS EXPECTED TO
MOVE IN SUNDAY WITH OFF/ON WET WEATHER POSSIBLE THROUGH THE
MIDDLE OF NEXT WEEK. MUCH OF THE MOISTURE SHOULD FALL LATE IN THE
WEEKEND AND EARLY INTO THE NEW WORK WEEK. THIS COULD RESULT IN MINOR
UPTICKS FOR RIVERS. THE LACK OF CONVECTIVE ACTIVITY...OR HIGH END
HEAVIER RAINFALL...KEEPS ME SOMEWHAT CONSERVATIVE ON ANY RISES
THAT WOULD OTHERWISE BE MORE CONCERNING.

&&

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

$$

SYNOPSIS...04
SHORT TERM...04
LONG TERM...OSTUNO
AVIATION...LAURENS
HYDROLOGY...JAM
MARINE...04







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