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000
FXUS63 KGRR 132350
AFDGRR

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

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 343 PM EDT SUN APR 13 2014

ADDITIONAL SHOWERS AND THUNDERSTORMS ARE EXPECTED TONIGHT AS A WAVE
OF LOW PRESSURE RIDES OF THE FRONTAL BOUNDARY THAT IS SITUATED
ACROSS SOUTHWEST LOWER MICHIGAN. ADDITIONAL HEAVY RAIN IS EXPECTED
WHICH WILL EXACERBATE AND EXPAND THE FLOODING THAT IS ALREADY
OCCURRING. SOME OF THE STORMS TONIGHT COULD REACH SEVERE LEVELS WITH
STRONG WINDS BEING THE MOST LIKELY THREAT. THE RAIN WILL TAPER OFF
INTO THE MIDDAY HOURS OF MONDAY. THE RAIN WILL MIX WITH AND CHANGE
OVER TO SNOW MONDAY AFTERNOON AND MONDAY NIGHT. SOME LIGHT SLUSHY
ACCUMULATIONS OF SNOW IS POSSIBLE. MUCH COLDER AIR WILL OBVIOUSLY
FILTER INTO THE REGION BEHIND THE FRONT THAT MOVES THROUGH THE AREA
ON MONDAY.

&&

.SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT)
ISSUED AT 343 PM EDT SUN APR 13 2014

HYDRO CONCERNS REMAIN PRIORITY ONE WITH ANOTHER ROUND OF SHOWERS AND
STORMS LOOMING FOR TONIGHT INTO MONDAY MORNING. HYDRO DETAILS ARE
CONTAINED BELOW IN THAT SECTION.

NEXT FOCUS IS ON THE POTENTIAL FOR SEVERE WEATHER TONIGHT. SURFACE
BASED CAPE VALUES ARE ON THE ORDER OF 1000-2000 J/KG FROM SOUTHEAST
LOWER MICHIGAN SOUTHWEST INTO KANSAS AND OKLAHOMA. THIS INSTABILITY
IS LOCATED JUST SOUTH OF A FRONTAL BOUNDARY WHICH WILL PROVIDE A
FOCUS FOR SHOWER AND THUNDERSTORM DEVELOPMENT. A WAVE OF LOW
PRESSURE WILL MOVE UP THE FRONT AND ENHANCE SHOWER AND THUNDERSTORM
DEVELOPMENT. THE SHORTWAVE IN THE PLAINS IS ACTUALLY VERY HEALTHY
LOOKING AS HAS RESULTED IN A LINE OF STORMS ALREADY IN KANSAS AHEAD
OF IT. EXPECTING ADDITION STORMS TO DEVELOP NORTH OF THIS UP THE
FRONTAL ZONE INTO LOWER MICHIGAN THIS EVENING. SOME OF THESE STORMS
WILL LIKELY DEVELOP INTO LINES AND BOWS AND HAVE THE POTENTIAL FOR
STRONG DAMAGING WINDS. ALL SHORT TERM MODELS ARE FORECASTING A LOW
LEVEL JET ON THE ORDER OF 60-70 KNOTS. THIS WIND IN PLACE COMBINED
WITH THE MID LEVEL ENERGY WILL BRING THE POTENTIAL FOR ANY LINE OF
BOW TO REACH SEVERE LEVELS. THE DRY SUB CLOUD LAYER OF YESTERDAY
WHICH ENHANCED GUSTS IS NOT AS PRONOUNCED TODAY WITH THIS MAY BE
OFFSET SOME BY THE STRONG WINDS AT 5000FT. WILL BE MONITORING STORMS
THIS EVENING INTO TONIGHT.

HEAVIER RAIN WILL PIVOT OFF TO THE EAST ON MONDAY. SOME LIGHT RAIN
CHANGING OVER TO LIGHT SNOW THOUGH IS EXPECTED ON THE BACKSIDE OF
THIS SYSTEM FOR MONDAY AFTERNOON AND MONDAY NIGHT. SOME LIGHT
ACCUMULATIONS ARE POSSIBLE...A SLUSHY INCH...BUT AT THIS POINT NOT
EXPECTING MORE THAN THAT.

.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 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 744 PM EDT SUN APR 13 2014

IMPACTS WILL INCREASE THROUGH THE NIGHT FOR AVIATORS. IFR LOOKS
LIKELY ESPECIALLY KGRR AND KMKG WITH THE HEAVIER RAIN.
THUNDERSTORMS WILL BE AROUND AS WELL ESPECIALLY WEST OF KLAN AND KJXN.
WINDS WILL INCREASE AND VALUES OVER 30 KTS EXPECTED. A SHARP WIND
SHIFT IS EXPECTED MONDAY MORNING INTO THE AFTERNOON. TEMPERATURES
WILL TURN COLDER AFTER THE WIND SHIFT. ICING MAY BECOME AN ISSUE
MONDAY AFTERNOON.



&&

.HYDROLOGY...
ISSUED AT 343 PM EDT SUN APR 13 2014

HAVE MAINTAINED THE FLOOD WATCH FOR THE ORIGINAL AREA. THE HEAVY
RAIN HAS FALLEN ACROSS THE WATCH AREA WHICH HAS WORKED OUT WELL.
AREAL FLOOD WARNINGS ARE IN PLACE FOR CENTRAL LOWER MICHIGAN OR THE
NORTHERN THREE ROWS OF THE GRR FORECAST AREA FROM
MUSKEGON...NEWAYGO...MONTCALM AND GRATIOT COUNTIES NORTHWARD.
QUITE A FEW RAINFALL TOTALS HAVE BEEN RECEIVED ACROSS CENTRAL LOWER
IN EXCESS OF 3 INCHES...WITH THE HIGHEST BEING NEAR THE MASON/OCEANA
COUNTY LINE NORTH OF MONTAGUE AT 3.82 INCHES.

ANOTHER BATCH OF SHOWERS AND STORMS WILL WORK THROUGH THE AREA
BETWEEN ABOUT 600 PM THIS EVENING THROUGH MONDAY MORNING. AN
ADDITIONAL 1 TO 2 INCHES OF RAIN IS EXPECTED WITH LOCALLY HIGHER
AMOUNTS ACROSS CENTRAL LOWER MI WHERE THEY DO NOT NEED ANY MORE
RAIN. THE AREAL FLOOD WARNING WILL LIKELY NEED TO BE EXTENDED AS THE
NEXT BATCH OF RAIN WILL RESULT IN ADDITIONAL FLOODING. NUMEROUS
RIVER ADVISORIES AND WARNINGS ARE IN PLACE WITH POTENTIALLY MORE TO
COME. SEVERAL SITES ARE FORECAST TO MOVE INTO THE MODERATE FLOOD
CATEGORY WHICH IS SIGNIFICANT FLOODING. SOME OF THE RAIN TONIGHT MAY
BE THE HEAVIEST OF THIS ENTIRE EVENT AS PARAMETERS LIKE PWAT (DEEP
MOISTURE) PEAK TONIGHT.

THE HEAVIER RAIN WILL COME TO AN END MIDDAY ON MONDAY MIXING WITH
AND CHANGING OVER TO SNOW DURING THE AFTERNOON AND OVERNIGHT.

&&

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

LM...NONE.
&&

$$

SYNOPSIS...DUKE
SHORT TERM...DUKE
LONG TERM...93
AVIATION...MJS
HYDROLOGY...DUKE