Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 181750
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
150 PM EDT MON AUG 18 2014

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 325 AM EDT MON AUG 18 2014

FAIR WEATHER WILL CONTINUE TODAY BEFORE A LOW PRESSURE SYSTEM
MOVING IN FROM THE NORTHERN PLAINS BRINGS SCATTERED SHOWERS AND A
FEW THUNDERSTORMS TONIGHT THROUGH TUESDAY. A FEW SHOWERS AND
STORMS MAY LINGER INTO WEDNESDAY. TEMPERATURES WILL BE NEAR NORMAL
THE NEXT FEW DAYS WITH HIGH TEMPERATURES IN THE UPPER 70S TO NEAR
80 DEGREES.

&&

.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 325 AM EDT MON AUG 18 2014

OUR PRIMARY SHORT TERM FCST CHALLENGE IS TO DETERMINE
PROBABILITIES FOR SHOWERS AND STORMS TONIGHT THROUGH WEDNESDAY.

A FAIRLY WEAK SURFACE AND UPPER LEVEL LOW PRESSURE SYSTEM WILL
MOVE IN FROM THE NORTHERN PLAINS TONIGHT THROUGH TUESDAY AND BRING
SCATTERED SHOWERS AND A FEW TSTORMS. OVERALL CONVECTIVE POTENTIAL
TONIGHT INTO TUESDAY LOOKS FAIRLY LOW THOUGH DUE TO RATHER WEAK
INSTABILITY AND A WEAK LLJ. MOISTURE TRANSPORT SHOULD BE SUFFICIENT
ENOUGH FOR A FEW STORMS THROUGH TUESDAY BUT NO SEVERE WEATHER IS
ANTICIPATED.

A FEW SHOWERS AND ISOLATED STORMS MAY LINGER TUESDAY NIGHT AND
WEDNESDAY WITH THE UPPER LEVEL LOW PRESSURE SYSTEM STILL OVER OUR
REGION. AS FOR TODAY... FAIR WX IS ANTICIPATED AFTER SOME PATCHY
EARLY MORNING FOG. MAX TEMPS WILL REACH THE UPPER 70S TO AROUND 80
DEGREES.

.LONG TERM...(WEDNESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 325 AM EDT MON AUG 18 2014

PRIMARY FORECAST ISSUE IN THE EXTENDED IS TRYING TO PIN DOWN THOSE
PERIODS THAT POPS CAN BE DROPPED. SFC AND SHORTWAVE UPPER RIDGING
SHOULD BRING FAIR WEATHER WEDNESDAY NIGHT AND EARLY THURSDAY BUT
WARM ADVECTION BEGINS THURSDAY WITH SHOWERS AND THUNDERSTORMS
EXPECTED NORTH OF THE SLOW MOVING SFC WARM FRONT...WITH THE HIGHEST
CHANCES ACROSS THE SOUTHERN FORECAST AREA. AN AREA OF ISENTROPIC
ASCENT CONTINUES TO BRING SHOWERS AND THUNDERSTORMS THURSDAY NIGHT
AND FRIDAY.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 139 PM EDT MON AUG 18 2014

THE TREND WILL BE FOR LOWERING CIGS IN THE 12Z-15Z TIME FRAME
POSSIBLY CLOSE TO IFR AS RA AND TSRA DEVELOPS AHEAD OF A FRONT IN
WISCONSIN TUESDAY. MODEL GUIDANCE IS NOT INDICATING IFR BUT
UPSTREAM OBSERVATIONS WHERE IT HAS RAINED IN WISCONSIN SUGGEST IFR
IS A DISTINCT POSSIBILITY...IN TERMS OF CIGS. HAVE THEREFORE
TRENDING CIGS TOWARD BUT NOT IN IFR FOR ALL SITES AS THE RA AND
TSRA MOVES IN DURING THE MORNING AND AFTERNOON HOURS. VISIBILITIES
SHOULD COME DOWN SOME BUT NOT IFR. CONDITIONS WILL LIKELY NOT
IMPROVE UNTIL AFTER 18Z FOR MKG AND POSSIBLY GRR AND AZO...AND A
FAIR AMOUNT LATER FOR LAN AND JXN.


&&

.MARINE...
ISSUED AT 325 AM EDT MON AUG 18 2014

WEAK OFFSHORE EASTERLY FLOW WILL RESULT IN WAVE HEIGHTS OF ONLY A
FOOT OR LESS TODAY. FAIRLY MINIMAL WIND AND WAVE ACTION IS
ANTICIPATED TONIGHT THROUGH MIDWEEK.


&&

.HYDROLOGY...
ISSUED AT 154 PM EDT SUN AUG 17 2014

RIVERS ARE RUNNING A LITTLE ABOVE NORMAL... BUT ARE STILL FAR BELOW
BANK FULL. PRECIPITATION THIS EVENING THROUGH WEDNESDAY IS EXPECTED
TO TOTAL AROUND HALF AN INCH. THIS SHOULD LEAD TO SLOW RISES ON AREA
RIVERS WITH PEAK LEVELS WELL BELOW FLOOD STAGE OCCURRING BY THE END
OF THE WEEK. LOCALLY HEAVY RAINFALL IS POSSIBLE AND COULD LEAD TO
BRIEFLY HIGHER FLOWS.

LOOKING AHEAD...IT APPEARS TO BE A RATHER ACTIVE SECOND HALF OF
AUGUST WHICH MAY HELP BRING MANY RIVERS TO ABOVE NORMAL FLOWS.
WITH AN UPPER LEVEL RIDGE DEVELOPING TO THE SOUTH OF THE GREAT
LAKES OVER THE NEXT WEEK OR SO...IT WILL PLACE MICHIGAN IN AN
ACTIVE WEATHER PATTERN WITH NUMEROUS OPPORTUNITIES FOR RAIN.


&&

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

$$

SYNOPSIS...LAURENS
SHORT TERM...LAURENS
LONG TERM...OSTUNO
AVIATION...HOVING
HYDROLOGY...63/HOVING
MARINE...LAURENS






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