615
FXUS63 KGRR 161821
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
221 PM EDT WED OCT 16 2013
LATEST UPDATE...
SYNOPSIS/SHORT TERM/LONG TERM/HYDRO/MARINE
.SYNOPSIS...
ISSUED AT 200 PM EDT WED OCT 16 2013
ONE AREA OF LOW PRESSURE WILL SLOWLY PULL AWAY FROM LOWER MICHIGAN
THIS EVENING TAKING THE LIGHT RAIN WITH IT. ANOTHER LOW PRESSURE
SYSTEM WILL TRACK IN FROM THE SOUTHWEST ON THURSDAY. THIS SYSTEM
WILL PROVIDE THE REGION WITH ANOTHER ROUND OF RAIN. COOLER AIR
WILL FLOW IN BEHIND THIS SECOND STORM SYSTEM AND PERSIST ACROSS
THE REGION THROUGH THE WEEKEND.
&&
.SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT)
ISSUED AT 200 PM EDT WED OCT 16 2013
THE MAIN CHALLENGE IN THE SHORT TERM DEALS WITH THE COVERAGE OF
THE RAIN THURSDAY. OVERALL I RAISED POPS FOR THU.
THERE IS A PRONOUNCED PV ANOMALY OVER SOUTHEAST CO...SEEN ON WV
IMAGERY. THIS SYSTEM STRENGTHENS AS IT TRACKS NORTHEAST INTO LOWER
MI THURSDAY. THROUGH MUCH OF THE NIGHT NOT MUCH RAIN THIS SYSTEM
WILL BE LARGELY VOID OF RAIN AS IF TRACKS TOWARD MI. HOWEVER WITH
DYNAMIC COOLING THE DGZ BECOMES SATURATED OVER CENTRAL AND
SOUTHERN LOWER MI BY 18Z. RAIN WILL BE EXPANDING AT THIS TIME.
DECENT FGEN IS NOTED WITHIN THE DGZ FROM ROUGHLY HOLLAND TO GRAND
RAPIDS TO LANSING 18Z TO 21Z THU. AS A RESULT I INCREASED POPS THU
FOR MUCH OF THE SOUTHERN 2/3RDS OF MY FORECAST AREA.
AS FOR TONIGHT I ALSO RAISED POPS FOR A FEW HOURS TO START THE
NIGHT. MOISTURE ENHANCED SOUTHWEST FLOW WILL PERSIST SUPPORTING
DECENT LOW LEVEL MOISTURE CONVERGENCE. THIS SHALLOW PRECIPITATION
EVENT WILL DISSIPATE WITH THE DIMINISHING WINDS BY MIDNIGHT.
.LONG TERM...(SATURDAY THROUGH WEDNESDAY)
ISSUED AT 200 PM EDT WED OCT 16 2013
A CONSENSUS OF LATEST MEDIUM RANGE GUIDANCE CONTINUES TO SUGGEST
THAT COOL AND UNSETTLED WEATHER WILL CONTINUE THROUGH THE LONG RANGE
FORECAST PERIOD. THIS AS AN UPPER LEVEL TROUGH REMAINS ENTRENCHED
OVER THE GREAT LAKES REGION AND A SERIES OF SHORTWAVES MOVES
THROUGH.
THIS PATTERN IN CONJUNCTION WITH RELATIVELY COLD H8 TEMPS WILL
RESULT IN SCATTERED SHOWERS DAILY THAT WILL BE ENHANCED BY THE LAKE.
MAX TEMPS DAILY WILL ONLY REACH THE UPPER 40S TO LOWER 50S WITH MINS
IN THE 30S TO LOWER 40S.
SOME PATCHY FROST OR EVEN FREEZING CONDITIONS ARE POSSIBLE DURING
THE EARLY MORNING HOURS SUNDAY THROUGH WEDNESDAY. HOWEVER THIS IS
CONTINGENT ON AMOUNT OF CLEARING NIGHTLY AND THE OVERALL WX PATTERN
FAVORS A FAIR AMOUNT OF CLOUD COVER TO LINGER THROUGH MOST OF THE
LONG RANGE FORECAST PERIOD.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY)
ISSUED AT 1230 PM EDT WED OCT 16 2013
MVFR CIGS ARE EXPECTED TO CONTINUE AT ALL THE TERMINALS THIS
AFTERNOON AND TONIGHT WITH LOW CLOUD BASES OF 1.5 TO 2.5 KFT AGL
AND SCATTERED LIGHT RAIN SHOWERS. CONDITIONS SHOULD STAY MAINLY MVFR
TONIGHT BUT MAY DETERIORATE TO IFR CONDITIONS AT TIMES THURSDAY AS
STEADIER RAIN DEVELOPS AND LOW CLOUDS CONTINUE TO LINGER.
&&
.MARINE...
ISSUED AT 200 PM EDT WED OCT 16 2013
THE STRONGER SOUTHWEST FLOW WILL WEAKEN OVERNIGHT AS THE STORM
SYSTEM PULLS AWAY. THE 4 TO 7 FOOT WAVES WILL SUBSIDE AS A RESULT.
WILL MAINTAIN THE HEADLINE THAT RUNS THROUGH MOST OF THE NIGHT. A
LULL IN THE WAVES IS FORECASTED FOR THURSDAY. THEN THEY WILL BUILD
AGAIN BY FRI AM...POSSIBLY REQUIRING ANOTHER SMALL CRAFT ADVISORY.
&&
.HYDROLOGY...
ISSUED AT 200 PM EDT WED OCT 16 2013
PERIODS OF RAIN WILL PERSIST INTO THE WEEKEND. LAKE MI WILL
ENHANCE SOME OF THE RAIN. AMOUNTS ARE NOT EXPECTED TO LEAD TO
CONSIDERABLE RISES ON AREA RIVERS. MOST LOCATIONS WILL SEE LESS
THAN THREE QUARTERS OF AN INCH OF RAIN THROUGH THE WEEKEND.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 6 AM EDT THURSDAY FOR LMZ844>849.
&&
$$
SYNOPSIS...MJS
SHORT TERM...MJS
LONG TERM...LAURENS
AVIATION...LAURENS
HYDROLOGY...MJS
MARINE...MJS