000
FXUS63 KGRR 180515
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
115 AM EDT TUE JUN 18 2013

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 335 PM EDT MON JUN 17 2013

A COLD FRONT WILL SLIP SOUTH THROUGH THE REGION THIS EVENING
BRINGING WITH IT THE CHANCE FOR SHOWERS AND THUNDERSTORMS. A FEW OF
THE STORMS THIS EVENING MAY BE STRONG WITH DAMAGING WINDS AND HAIL.
DRY WEATHER IS EXPECTED LATE TONIGHT AS HIGH PRESSURE BEGINS TO
BUILD INTO THE GREAT LAKES. THE HIGH WILL REMAIN SITUATED OVER THE
AREA THROUGH MUCH OF THE WORK WEEK BRINGING DRY WEATHER THROUGH
FRIDAY. HIGHS WILL BE COOLER TUESDAY AND WEDNESDAY BEHIND THE FRONT
IN THE LOWER TO MIDDLE 70S. A WARMING TREND IS EXPECTED LATER IN THE
WEEK WHICH WILL PUSH HIGHS BACK INTO THE 80S BY FRIDAY.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT)
ISSUED AT 335 PM EDT MON JUN 17 2013

MAIN CONCERN IN THE SHORT TERM REVOLVES AROUND THE CONVECTIVE THREAT
THIS EVENING AND CHANCES FOR SEVERE. OTHERWISE...QUIET WEATHER IS
EXPECTED THE REMAINDER OF THE SHORT TERM.

INSTABILITY HAS BUILT SOME THIS AFTERNOON WITH SURFACE BASED CAPE
VALUES IN EXCESS OF 1000 J/KG. LI VALUES HAVE DIPPED TO AROUND -4C.
SURFACE MOISTURE MIXING OUT HAS LIMITED THE INSTABILITY POTENTIAL
SOME THOUGH AS EXPECTED. CONVECTION THIS AFTERNOON AND EVENING DOES
HAVE SYNOPTIC SCALE SUPPORT GOING FOR IT THOUGH IN REGARD TO
ENTRANCE REGION JET STREAK UPPER DIVERGENCE AND A MID LEVEL
SHORTWAVE SWINGING THOUGH. IN ADDITION...DEEP LAYER 0-6KM SHEAR
VALUES ARE IN EXCESS OF 40 KNOTS WHICH HAS ALLOWED STORMS TO ROTATE
AND BECOME SEVERE. LARGE HAIL HAS BEEN REPORTED IN SAGINAW COUNTY
OVER IN DTX/S FORECAST AREA. A LAKE SHADOW OF STABILITY DOES EXIST
AND WE WILL CONTINUE TO MONITOR STORMS ROLLING SOUTHEAST OUT OF
WISCONSIN AND THE CHANCE THAT ADDITIONAL STORMS MAY FIRE IN THE
EASTERN CWA. CONVECTION SURVIVED A LAKE TRIP YESTERDAY EVENING AND
MAY THIS EVENING AS WELL GIVEN THE QUICK FLOW AND THE CHANCE THAT IT
MAY NOT ROOT IN THE BOUNDARY LATER. BOTTOM LINE...SCATTERED
CONVECTION EXPECTED THROUGH THE EVENING.

THE NAM INDICATES SOME CLOUDS DROPPING SOUTH TONIGHT POST FRONTAL
AND FEEL IT MAY BE ONTO SOMETHING. TRIED TO INCREASE CLOUD COVER
SOME TONIGHT INTO TUESDAY IN A BANDED CLOUD STRUCTURE ON THE NORTH
SIDE OF THE SURFACE FRONT. OTHERWISE DRY WEATHER FORECAST FROM
TONIGHT THROUGH WEDNESDAY NIGHT.

.LONG TERM...(THURSDAY THROUGH MONDAY)
ISSUED AT 335 PM EDT MON JUN 17 2013

FORECAST CONCERNS DEAL WITH CONVECTIVE POTENTIAL.

THE CONVECTIVE THREAT BEGINS FRIDAY NIGHT AS AN UPPER RIDGE BUILDS
TO THE WEST. WE/LL SEE HEAT AND HUMIDITY INCREASE AS SOUTH FLOW
DEVELOPS UNDER PARTLY CLOUDY SKIES. TEMPERATURES WILL CLIMB TO THE
MID TO UPPER 80S OVER THE WEEKEND. THE SFC PROG SHOWS A LOW OVER SW
MINNESOTA WITH A WARM FRONT EXTENDING EWD ACROSS NRN WISCONSIN. A
NOCTURNAL LLJ FRIDAY NIGHT THROUGH SUNDAY NIGHT COULD POINT TOWARD A
MCS DEVELOPING ACROSS CENTRAL MINNESOTA/NW WISCONSIN NEAR THE WARM
FRONT. LOW/MID LEVEL THICKNESS PATTERN WOULD CARRY THE MCS ACROSS
THE CWA DURING THE LATE NIGHT/MORNING HOURS. SO WE/LL KEEP AN EYE ON
THAT. GIVEN THE STEADY INCREASE IN MOISTURE...HEAVY RAIN WILL BECOME
A CONSIDERATION IN ANY THUNDERSTORM.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 115 AM EDT TUE JUN 18 2013

AREAS OF MVFR ALONG WITH PATCHY IFR ARE EXPECTED OVERNIGHT AS LOW
CLOUDS REMAIN IN THE WAKE OF THE SCATTERED THUNDERSTORMS FROM
MONDAY EVENING. LOW CLOUDS ARE EXPECTED TO BREAK UP BY 18Z WITH
VFR CONDITIONS TUESDAY AFTERNOON AND EVENING.

&&

.MARINE...
ISSUED AT 335 PM EDT MON JUN 17 2013

WINDS WILL SHIFT TO THE NORTH TONIGHT AND INCREASE INTO THE 10 TO 20
KNOT RANGE WHICH WILL BUILD WAVES HEIGHTS INTO THE 1 TO 3 FOOT
RANGE. SLIGHTLY HIGHER WINDS AND WAVES CAN BE EXPECTED ON THE OPEN
WATERS. WAVES WILL REMAIN UP SLIGHTLY ON TUESDAY BEFORE SUBSIDING
FOR MUCH OF THE MID WEEK PERIOD WITH HIGH PRESSURE IN PLACE.


&&

.HYDROLOGY...
ISSUED AT 335 PM EDT MON JUN 17 2013

TWO RIVER ADVISORIES REMAIN FROM RECENT HEAVY RAINS. TONIGHT/S RAIN
SHOULD BE SCATTERED IN NATURE DUE TO STORMS...SO NOT MUCH AFFECT IS
EXPECTED ON AREA RIVERS. DRY WEATHER IS THEN FORECAST FROM TUESDAY
THROUGH FRIDAY. RIVERS SHOULD FALL THROUGH THE END OF THE WEEK FROM
WHAT ARE ABOVE NORMAL VALUES ACROSS THE GRAND RIVER BASIN.

&&

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

$$

SYNOPSIS...DUKE
SHORT TERM...DUKE
LONG TERM...93
AVIATION...OSTUNO
HYDROLOGY...DUKE
MARINE...DUKE