Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 160344
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1144 PM EDT TUE APR 15 2014

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 328 PM EDT TUE APR 15 2014

EXPECT MOSTLY CLEAR SKIES TONIGHT WITH VERY COLD TEMPERATURES...
SOME RECORD LOWS ARE NOT OUT THE QUESTION. A STORM SYSTEM PASSING
THROUGH WISCONSIN WEDNESDAY NIGHT INTO THURSDAY MORNING WILL BRING
A CHANCE OF SHOWERS TO NORTH OF MUSKEGON DURING THURSDAY MORNING.
THIS WILL BRING A SURGE OF WARMER AIR TO THE AREA THURSDAY WITH
HIGHS WELL UP INTO THE 50S. A COLD FRONT WILL COME THROUGH THE
AREA EARLY FRIDAY MORNING BRINGING COOLER TEMPERATURES AND A GOOD
CHANCE OF SHOWERS THAT MAY MIX WITH SNOW NORTH OF INTERSTATE 96 BY
SUNRISE FRIDAY.

&&

.SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT)
ISSUED AT 328 PM EDT TUE APR 15 2014

THE MAIN ISSUE TONIGHT WILL BE JUST HOW COLD IT WILL GET. NEAR
RECORD LOWS ARE POSSIBLE AT GRAND RAPIDS AND MUSKEGON. THE NEXT
ISSUE IS THE SYSTEM PASSING TO OUR NORTHWEST WEDNESDAY NIGHT WITH
RESPECT TO HOW FAR SOUTH THE SHOWER WILL GET INTO OUR NORTHERN
CWA. THEN THERE IS THE ISSUE FOR FRIDAY MORNING... WILL THE
SHOWERS WITH THE COLD FRONT MIX WITH AND CHANGE TO SNOW BY MORNING?

TONIGHT THE CENTER OF THE HIGH PRESSURE RIDGE MOVES OVER LOWER
MICHIGAN BY MIDNIGHT. AT THE SAME TIME THE POLAR JET MOVES EAST
ACROSS LOWER MICHIGAN TAKING SOUTHWEST MICHIGAN OUT OF THE DEEP
COLD AIR. ALL OF THIS SHOULD LEAD TO CLEAR SKIES AND LIGHT WINDS
WHICH WILL ALLOW TEMPERATURES TO FALL IN THE TEENS NORTH AND LOWER
TO MID 20S SOUTH. THE RECORD LOW AT MUSKEGON IS 20 SET IN
1907...THE RECORD LOW AT GRAND RAPIDS IS 21 IN 1904... IT POSSIBLE
MORNING LOWS COULD FALL BELOW THESE RECORDS. LANSING AS A RECORD
LOW OF 10 SET IN 1875...THAT WOULD SEEM TO BE OUT OF REACH TONIGHT.

THE NEXT SYSTEM TO IMPACT THE AREA IS A NORTHERN STREAM SYSTEM
THAT TRACKS ACROSS NORTHERN WISCONSIN INTO NORTHERN LOWER MICHIGAN
THURSDAY MORNING. THE UPPER LEVEL JET CORE THAT SUPPORTS THIS
SYSTEM WILL BE OVER NORTHERN WISCONSIN AND UPPER MICHIGAN. THE JET
ENTRANCE REGION LIFT WILL BE MOSTLY OVER NORTHERN LOWER MICHIGAN.
THERE IS A 50 TO 60 KNOT LOW LEVEL JET WITH THIS AND THE PWAT
VALUES REACH TO NEAR 0.7 INCHES... WHICH IS IN THE TOP 25 PERCENT
OF WHAT IS NORMAL FOR THIS TIME OF YEAR. MORE THAN ENOUGH FOR
SHOWERS. WITH THE BEST DYNAMICS OVER NORTHERN LOWER...ONLY OUR
NORTHERN COUNTIES SHOULD SEE SHOWERS FROM THIS (MID LEVELS ARE TO
WARM FOR SNOW).

THE JET ENTRANCE REGION OF THAT JET CORE AIDS THE DEVELOPMENT OF A
WAVE ON THE COLD FRONT AS IT COMES THROUGH THURSDAY NIGHT INTO
FRIDAY MORNING. THE PRECIPITABLE WATER IS EVEN HIGHER FRIDAY
MORNING SO IT WOULD SEEM TO ME THE RISK OF PRECIPITATION IS ON THE
HIGH SIDE. THE ONLY REAL QUESTION HERE IS WILL THE THERE BE ENOUGH
COLD AIR TO TURN THE RAIN TO SNOW BY FRIDAY MORNING. THE GOOD NEWS
IS PRECIPITATION AMOUNTS FROM BOTH OF THESE SYSTEMS WILL BE LESS
THAN A QUARTER INCH SO THERE SHOULD NOT BE MUCH IMPACT ON OUR
ALREADY HIGH RIVER LEVELS.

.LONG TERM...(FRIDAY THROUGH TUESDAY)
ISSUED AT 328 PM EDT TUE APR 15 2014

QUASI ZONAL FLOW ACROSS THE NORTHERN US WILL LEAD TO FREQUENT
SYSTEMS MOVING ACROSS THE CWA. AT THE BEGINNING OF THE PERIOD LOW
PRESSURE MOVING ACROSS THE GREAT LAKES WILL BRING LIGHT RAIN THAT
WILL PROBABLY TURN OVER TO LIGHT SNOW FRIDAY NIGHT. ANOTHER WAVE
WILL APPROACH SATURDAY NIGHT AND BRING THE THREAT OF LIGHT RAIN
THROUGH THE WEEKEND INTO MONDAY. THE JET WILL BE ACROSS NRN LWR
DURING THIS TIME WHICH WILL MEAN THE COLDEST AIR WILL REMAIN NORTH
OF THE CWA. HIGHS WILL BE IN THE 40S FRIDAY MODERATING TO THE 50S
OVER THE WEEKEND AND NEAR 60 BY NEXT TUESDAY.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1142 PM EDT TUE APR 15 2014

VFR WEATHER TO PREVIAL THROUGH THE PERIOD. CLOUDS WILL BE
STREAMING IN OVERNIGHT BUT THEIR BASES WILL BE AT VFR LEVELS.
WINDS WILL INCREASE WEDNESDAY AFTERNOON AND GUSTS OVER 25 KNOTS
WILL BE POSSIBLE.

&&

.HYDROLOGY...
ISSUED AT 1205 PM EDT TUE APR 15 2014

RIVER FORECASTS NOW HAVE 3 SITES GOING TO MAJOR FLOOD
STATUS...SCOTTVILLE ON THE PERE MARQUETTE...CROTON ON THE MUSKEGON
AND EVART ON THE MUSKEGON. FLOODING ISSUES CONTINUE ACROSS MUCH OF
CENTRAL LOWER MICHIGAN. AREAL FLOOD WARNINGS REMAIN IN EFFECT.
EVART IS CURRENTLY AT RECORD FLOOD LEVELS.

THE FLASH FLOOD WATCH WAS DROPPED FOR THE DAM JUST NORTH OF REED
CITY AS CONDITIONS THERE HAVE STABILIZED. THE FLASH FLOOD WATCH
CONTINUES FOR THE DAM ON THE WHITE RIVER AT WHITE CLOUD AS
ASSESMENTS CONTINUE IN THAT LOCATION.

&&

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

$$

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






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