Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 131415
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1015 AM EDT SUN APR 13 2014

LATEST UPDATE...
UPDATE

.SYNOPSIS...
ISSUED AT 330 AM EDT SUN APR 13 2014

LOW PRESSURE TRACKING NORTHEAST INTO OUR REGION WILL CAUSE RAIN
AND THUNDERSTORMS TO CONTINUE TO DEVELOP. RAIN AND STORMS SHOULD
BECOME MOST PREVALENT LATE THIS AFTERNOON THROUGH TONIGHT AND WILL
BRING POTENTIAL FOR HEAVY RAIN. COLD AIR WILL WRAP IN ON THE BACK
SIDE OF THIS SYSTEM MONDAY THROUGH MONDAY NIGHT AND CAUSE LINGERING
PRECIPITATION TO MIX WITH THEN CHANGE TO LIGHT SNOW BEFORE ENDING.
FAIR WEATHER WILL RETURN TUESDAY AND WEDNESDAY.

&&

.UPDATE...
ISSUED AT 1013 AM EDT SUN APR 13 2014

UPDATED TO TWEAK POPS AFTER 18Z. TIMING TOOL SHOWS CONVECTION OVER
NRN MISSOURI MOVING OVER SRN LAKE MICHIGAN AROUND 19Z.

UPDATE ISSUED AT 810 AM EDT SUN APR 13 2014

UPDATED TO LOWER POPS CONSIDERABLY THROUGH 18Z AS RADAR/SATELLITE
TRENDS... AS WELL AS SHORT TERM MODEL GUIDANCE... INDICATE A MAJOR
LULL IN PRECIP THROUGH EARLY/MID AFTERNOON. THE LOW LEVEL JET IS
PROGGED TO REDEVELOP/RELOAD AFTER 18Z... STRENGTHENING TO 60+
KNOTS BY 00Z. THIS WILL GET THINGS GOING AGAIN BY LATE IN THE DAY
AND ESPECIALLY THIS EVENING.

&&

.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 330 AM EDT SUN APR 13 2014

SEVERAL ROUNDS OF RAIN AND TSTORMS ARE ANTICIPATED TODAY THROUGH
TONIGHT. ELEVATED CONVECTION IS ANTICIPATED WITH DECENT ELEVATED
INSTABILITY STILL IN PLACE WITH H8 LI/S DOWN TO AROUND -2
TO -4. HOWEVER SOME OF THE LATEST HIGHER RESOLUTION COMPUTER
GUIDANCE ALSO SUGGESTS THAT THERE COULD BE FAIRLY SIGNIFICANT
LULLS IN RAIN/TSTORM ACTIVITY UNTIL MID TO LATE AFTERNOON.

HOWEVER THE BEST CHANCE FOR WIDESPREAD HEAVIER RAINFALL AND STRONGEST
CONVECTION SHOULD COME FROM MID OR LATE AFTERNOON THROUGH THE
EVENING HOURS AS THE MAIN PLAINS STATES LOW TRACKS NE INTO OUR
REGION THIS EVENING.

1000-850 MB MOISTURE TRANSPORT RAMPS UP SIGNIFICANTLY LATE THIS
AFTERNOON AND EVENING SUGGESTING POTENTIAL FOR HEAVY RAIN WITH
PRECIPITABLE WATER VALUES ALSO VERY HIGH. THE LLJ RAMPS UP
SIGNIFICANTLY THIS EVENING TO AROUND 55 TO 65 KTS. INSTABILITY
WILL BE LIMITED BUT THERE WILL BE SUFFICIENT FORCING FROM THE LLJ
AND APPROACHING FRONT AS WELL AS PLENTY OF MOISTURE. WILL ALSO NEED
TO MONITOR CLOSELY FOR POTENTIAL STRONG TO SEVERE STORMS GIVEN
SEVERAL FAVORABLE INGREDIENTS AS WELL AS STRONG SHEAR.

BRISK NW FLOW CAA WILL OCCUR ON THE BACK SIDE OF THIS SYSTEM
MONDAY CAUSING LINGERING LIGHTER PCPN TO BECOME MIXED WITH THEN
CHANGE TO LIGHT SNOW. ANY LIGHT SNOW MONDAY MORNING OR AFTERNOON
SHOULD MELT BUT THERE IS POTENTIAL FOR LIGHT ACCUMULATIONS MAINLY
FOR MONDAY EVENING THROUGH MONDAY NIGHT. HIGH PRESSURE WILL BUILD
IN TO PRODUCE FAIR BUT COLD WEATHER TUESDAY.

THE FLOOD WATCH REMAINS IN EFFECT AND UNCHANGED SINCE THERE
CONTINUES TO BE POTENTIAL FOR SEVERAL MORE ROUNDS OF RAIN AND
STORMS AND RAIN COULD BE HEAVY AT TIMES. THE GREATEST POTENTIAL
FOR WIDESPREAD HEAVY RAIN AT TIMES SHOULD COME LATE THIS AFTERNOON
AND TONIGHT.

.LONG TERM...(TUESDAY NIGHT THROUGH SATURDAY)
ISSUED AT 330 AM EDT SUN APR 13 2014

THE MID TO LATE WEEK PERIOD WILL FEATURE TEMPERATURES MODERATING
BACK TO NEAR NORMAL... WITH A CHANCE OF RAIN SHOWERS MAINLY ON
FRIDAY.

AS ANOTHER UPPER TROUGH DIGS OVER THE CENTRAL U.S. ON THURSDAY...
ANOTHER FRONTAL BOUNDARY EVENTUALLY DEVELOPS FROM LWR MI SW TO
MISSOURI BY LATE IN THE WEEK. HOWEVER THIS FRONT DOES NOT LOOK
NEARLY AS ACTIVE AS THE CURRENT ONE AND HAS MUCH LESS MOISTURE TO
WORK WITH. ACTUALLY THE FRONT APPEARS TO WEAKEN/DISSOLVE ON FRIDAY
AND FRIDAY NIGHT AS IT MOVES THROUGH THE AREA.

THE STRONG SFC LOW SHOWN BY THE 00Z GFS MOVING ALONG THE FRONT FOR
FRIDAY AND FRIDAY NIGHT IS NOT IN THE ECWMF/UKMET SOLUTIONS SO IS
BEING DISCOUNTED AT THIS TIME. BEST CHANCE OF RAIN LOOKS TO BE ON
FRIDAY AS THE UPPER TROUGH AND SFC FRONT PASS THROUGH.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 754 AM EDT SUN APR 13 2014

A SEVERAL HOUR BREAK FROM SHOWERS AND TSTMS IS LIKELY THIS MORNING
INTO MID AFTERNOON. DURING THIS TIME CONDITIONS SHOULD BE
PREDOMINATELY VFR. SHOWERS AND TSTMS ARE EXPECTED TO DEVELOP
AFTER 21Z AND BECOME MORE NUMEROUS AFTER 00Z. CONDITIONS SHOULD
TREND DOWN TO MVFR AFTER 00Z... WITH IFR BECOMING LIKELY AT MKG
AND GRR AFTER DARK. WINDS WILL INCREASE OUT OF THE SOUTH LATER
TONIGHT WITH GUSTS OF 30 KTS OR MORE POSSIBLE TONIGHT. A WIND
SHIFT TO THE NORTHWEST WILL OCCUR AT MKG AND GRR AFTER 09Z
TONIGHT.


&&

.HYDROLOGY...
ISSUED AT 1057 PM EDT SAT APR 12 2014

TRAINING CELLS CONTINUE JUST NORTH OF A MUSKEGON TO GRAND RAPIDS
TO LANSING LINE. IT IS LIKELY THAT FLOODING IS OCCURRING IN SOME
PLACES WITH CONDITIONS EXPECTED TO WORSEN OVERNIGHT. INITIALLY
RADAR WAS OVERESTIMATING THE PRECIPITATION...HOWEVER WITH DEEPER
MOISTURE NOW IN PLACE THE CELLS WILL BE MORE EFFICIENT THROUGH THE
NIGHT. THE COUNTY LINE BETWEEN OCEANA AND MUSKEGON COUNTIES LIKELY
HAS SEEN THE MOST RAINFALL SO FAR.

ADDITIONAL STORMS STRETCH INTO WISCONSIN SO THESE ROUNDS OF HEAVY
RAIN WILL PERSIST INTO LATE NIGHT.

AS FOR THE LARGER RIVERS...SEEMS LIKE THE SITUATION IS GOING DOWN
AS EXPECTED...SO NO MAJOR CHANGES WITH THE EVENING UPDATE. PLENTY
OF POTENTIAL FOR MODERATE FLOODING IN PLACES AND AN ELEVATED RISK
FOR MAJOR FLOODING. EVART AND CROTON RISE INTO MODERATE FLOODING.
UNCERTAINTY EXISTS WHERE THE SUNDAY CONVECTION WILL ULTIMATELY
SET UP. THIS WILL NEED TO BE MONITORED CLOSELY.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...FLOOD WATCH THROUGH MONDAY MORNING FOR MIZ037>040-043>046-
     050>052-056>058-064.

LM...NONE.
&&

$$

UPDATE...93
SYNOPSIS...LAURENS
SHORT TERM...LAURENS
LONG TERM...MEADE
AVIATION...MEADE
HYDROLOGY...MJS






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