Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 131928
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
326 PM EDT SUN APR 13 2014

LATEST UPDATE...
LONG TERM

.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 1024 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. LITTLE IF ANY
ELEVATED INSTABILITY NORTH OF SOUTH HAVEN TO SAGINAW BAY LINE THIS
AFTERNOON. MUCH OF THE ELEVATED INSTABILITY IS OVER THE SRN CWA.
MUCAPE AROUND 1K J/KG PROGD NEAR JACKSON. LATEST VIS LOOP SHOWS
SOME CLEARING MOVING INTO FAR SOUTHERN LOWER MI. THIS WON/T LAST
LONG BUT WILL HELP TO DESTABILIZE THE ATM A BIT. WE ARE NOT IN A
SLIGHT RISK AREA TODAY...BUT A FEW STRONG STORMS SEEM POSSIBLE
AFTER 18Z. ONE LIMITING FACTOR IS THE TIMING OF THE STRONGER LLJ.
IT DOESN/T MOVE OVER THE CWA UNTIL AFTER 00Z. SO THE WINDOW FOR
STRONGER STORMS MAY BE FROM VERY LATE THIS AFTERNOON THROUGH MID
EVENING.

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 THROUGH SUNDAY)
ISSUED AT 326 PM EDT SUN APR 13 2014

A TASTE OF WINTER WILL RETURN TUESDAY AS ARCTIC AIR FLOWS INTO THE
REGION. HIGHS IN THE MID 30S WILL FEEL QUITE CHILLY COMPARED TO THE
60S AND 70S OF LATE. H8 TEMPS NEAR -16C WILL CREATE ENOUGH
INSTABILITY OVER THE LAKE TO PRODUCE SOME LAKE EFFECT SNOW SHOWERS.
ACCUMS WILL BE LIMITED IF ANY THOUGH...MAINLY A HALF INCH OR LESS.

WARMER AIR WILL RETURN MID WEEK AS THE UPPER TROUGH MOVES EAST.
DEVELOP LOW PRESSURE IN THE PLAINS WILL PUSH WARMER AIR BACK INTO
LOWER MICHIGAN BY WEDNESDAY AND WE/LL SEE HIGHS IN THE 50S.

THE NEXT CHANCE OF RAIN WILL COME THURSDAY NIGHT AND LAST THROUGH
SUNDAY. THE PLAINS LOW WILL MOVE SOUTH TO TEXAS IN RESPONSE TO A
DIGGING UPPER JET. THIS IN TURN WILL CREATE A NEGATIVELY TROUGH FROM
TEXAS INTO THE GREAT LAKES THAT WILL ACT AS AN AVENUE FOR THE LOW TO
MOVE NORTH. MOISTURE WILL ALSO FLOW NORTHWARD LATE IN THE WEEK.
THUNDER MAY BE A POSSIBILITY FRIDAY AFTERNOON WITH LI/S LESS THAN
0C.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 156 PM EDT SUN APR 13 2014

ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS WILL DEVELOP/MOVE INTO
THE REGION LATER THIS AFTERNOON AND CONTINUE TONIGHT. LOOK FOR
CIGS/VSBYS TO DROP ONCE AGAIN. HOWEVER...MUCH OF THIS AFTERNOON
WILL SEE VFR CONDITIONS.

&&

.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...93
AVIATION...93
HYDROLOGY...MJS









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