Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 220719
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
319 AM EDT FRI MAY 22 2015

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

.SYNOPSIS...
ISSUED AT 318 AM EDT FRI MAY 22 2015

HIGH PRESSURE WILL BRING COOL AND DRY WEATHER TODAY AND
SATURDAY...THEN A WARM FRONT WILL BRING SOME RAIN ON
SUNDAY. A MOIST SOUTHERLY FLOW BEGINS ON MONDAY AND NEXT WEEK
WILL SEE THE CHANCE OF SHOWERS EACH DAY.

&&

.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 318 AM EDT FRI MAY 22 2015

LOOKS LIKE ANOTHER ROUND OF FROST AND FREEZING TEMPERATURES FOR
THE NORTHERN HALF OF THE FORECAST AREA TONIGHT AS SFC HIGH MOVES
OVERHEAD WITH GOOD RADIATIONAL COOLING CONDITIONS FOR MUCH OF THE
NIGHT. MAY NEED A FREEZE WARNING FOR THE NORTHERN TIER AND A FROST
ADVISORY FOR AT LEAST THE ROW OF COUNTIES SOUTH OF THERE.

SFC HIGH MOVES EAST SATURDAY AND RETURN FLOW SETS UP WITH
ISENTROPIC ASCENT DEVELOPING NORTH OF THE SFC WARM FRONT BY
SATURDAY NIGHT...BUT PRECIP SHOULD HOLD OFF UNTIL SUNDAY WHEN
STRENGTHENING MID LEVEL WAA AND MOISTURE RETURN RESULT IN WARM
ADVECTION WING OF SHOWERS TO DEVELOP. THE MODELS HAVE BEEN
CONSISTENT IN SHOWING THIS THE PAST SEVERAL DAYS SO THERE IS
FAIRLY HIGH CONFIDENCE THAT THE RAINS WILL ARRIVE SUNDAY
AFTERNOON. POTENTIAL FOR THUNDER STILL LOOKS LIMITED BY LACK OF
INSTABILITY.

.LONG TERM...(SUNDAY NIGHT THROUGH THURSDAY)
ISSUED AT 318 AM EDT FRI MAY 22 2015

THE LONG TERM PERIOD LOOKS MILD AND WET. A NORTHWARD LIFTING WARM
FRONT WILL BE THE FOCUS FOR SHOWERS AND SCATTERED STORMS SUNDAY
NIGHT. A 40 KT LLJ CROSSING THE FRONT WILL PRODUCE THE MOST PCPN
OVER THE NRN CWA. THE TRAILING COLD FRONT WILL HANG UP OVER THE CWA
FOR MUCH OF THE REST OF THE PERIOD. HIGH PRESSURE OVER THE WESTERN
ATLANTIC WILL RESULT IN A STEADY FEED OF MOISTURE NORTHWARD FROM THE
GULF AND SEVERAL SHORT WAVES RIDING NORTHEASTWARD ALONG THE QUASI
STATIONARY FRONTAL BOUNDARY WILL PRODUCE PERIODIC SHOWERS/STORMS.

HIGHS IN THE MID TO UPPER 70S COMBINED WITH DEWPOINTS IN THE 60S
WILL MAKE IT FEEL MUGGY FROM MEMORIAL DAY THROUGH THE REST OF THE
WEEK.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 117 AM EDT FRI MAY 22 2015

A WEAK COLD FRONT IS MOVING THROUGH LOWER MICHIGAN ATTM. WINDS
WILL SHIFT FROM THE SOUTHWEST TO THE NORTH BEHIND THE FRONT...BUT
REMAIN LIGHT OVERNIGHT. LIGHT RAIN SHOWERS ACCOMPANYING THE FRONT
WILL ALSO MOVE SOUTH OF THE TAF SITES BY 09Z. MOSTLY CLEAR SKIES
BEHIND THE FRONT.

&&

.MARINE...
ISSUED AT 318 AM EDT FRI MAY 22 2015

WINDS AND WAVES WILL BE RELATIVELY LIGHT TODAY AS HIGH PRESSURE
BUILDS IN. THE HIGH MOVES EAST ON SATURDAY AND SOUTH WINDS WILL
INCREASE BUT SHOULD REMAIN BLO 25 KNOTS.

&&

.HYDROLOGY...
ISSUED AT 1240 PM EDT THU MAY 21 2015

NO CONCERNS THROUGH THE WEEKEND. PRECIPITATION THAT COULD AFFECT
MAINSTEM RIVERS IS NOT EXPECTED UNTIL LATE SUNDAY...WHICH MARKS THE
START OF A WETTER PATTERN LASTING WELL INTO THE COMING WORK WEEK.
NATIONAL GUIDANCE ADVERTISES UNIFORM RAINFALL TOTALS OF 1-1.5
INCHES ACROSS THE AREA THROUGH THURSDAY MORNING. GIVEN THAT BASE
FLOWS ARE NEAR OR BELOW NORMAL AND THAT RAIN SHOULD BE SPREAD OUT
OVER TIME...WE EXPECT FAIRLY GENTLE RISES WILL BE UNDERWAY BY THE
MIDDLE OF NEXT WEEK.

THAT SAID...FORECASTING CONVECTIVE RAINFALL THIS FAR OUT IS
HIGHLY UNCERTAIN SO THERE STILL REMAINS A FAIRLY WIDE RANGE OF
POSSIBILITIES FOR RAINFALL AND RIVER RESPONSES AT THIS POINT.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...FROST ADVISORY UNTIL 9 AM EDT THIS MORNING FOR MIZ037>040-
     043>046.

LM...NONE.
&&

$$

SYNOPSIS...OSTUNO
SHORT TERM...OSTUNO
LONG TERM...04
AVIATION...04
HYDROLOGY...TJT
MARINE...OSTUNO


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