Area Forecast Discussion
Issued by NWS Grand Rapids, MI

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS63 KGRR 210112
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
912 PM EDT SAT SEP 20 2014

LATEST UPDATE...
UPDATE

.SYNOPSIS...
ISSUED AT 915 PM EDT SAT SEP 20 2014

A CHANCE FOR SHOWERS AND THUNDERSTORM OVERNIGHT WITH SHOWERS
LINGERING INTO SUNDAY. CLEARING IS EXPECTED TO OCCUR SUNDAY LATE
IN THE DAY WITH PATCH FROST POSSIBLE ACROSS NORTHERN LOWER
MICHIGAN SUNDAY NIGHT. PLEASANT WEEK EXPECTED WITH ONLY OCCASIONAL
CHANCES FOR SHOWERS/THUNDERSTORMS.

&&

.UPDATE...
ISSUED AT 915 PM EDT SAT SEP 20 2014

BREAK IN PRECIPITATION CHANCES THROUGH MIDNIGHT...WITH THE NEXT
SHOT FOR SHOWERS/THUNDERSTORMS COMING FROM THE AREA OF SHOWERS
CURRENTLY IN MINNESOTA AND WISCONSIN. THESE SHOULD ARRIVE IN THE
MIDDLE OF THE NIGHT BUT SEVERE WEATHER IS NOT ANTICIPATED AT THIS
TIME. SOME BREEZY CONDITIONS AND LIGHTNING ALONG WITH BRIEF HEAVY
DOWNPOURS POSSIBLE.

&&

.SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT)
ISSUED AT 319 PM EDT SAT SEP 20 2014

FORECAST CONCERNS DEAL WITH SEVERE POTENTIAL TONIGHT.

RADAR TRENDS SHOW STORMS CONTINUING TO DEVELOP ACROSS THE CWA.
INSTABILITY HAS INCREASED A BIT WITH LI/S NEAR -2C. HOWEVER THERE IS
STILL QUITE A BIT OF CONVECTIVE INHIBITION IN PLACE. THAT CINH
DECREASES TOWARD THE FAR SRN CWA. IF WE`RE GOING TO SEE SVR STORMS
THIS AFTERNOON THEY WILL BE OVER THE FAR SRN CWA. THIS IS ALSO WHERE
THE GREATEST SHEAR IS...NEAR 50 KTS. MID LEVEL JET MOVING IN WILL
ALSO AID IN STORM DEVELOPMENT. SPC HAS PLACED THE SRN ROW OF
COUNTIES IN A SVR WATCH INTO THE EVENING. THE SVR POTENTIAL WILL
LAST THROUGH MID TO LATE EVENING AND WIND GUSTS IN THE 50-60 MPH
RANGE ARE THE MAIN THREAT.

A WAVE DEVELOPING ON THE FRONTAL BOUNDARY IN CONJUNCTION WITH A
STRONG SHORT WAVE MOVING ACROSS THE GREAT LAKES WILL RESULT IN
SHOWERS IN THE GRIDS TONIGHT AND SUNDAY MORNING. HIGH PRESSURE
BUILDS SOUTH BY AFTERNOON SETTING THE STAGE FOR GOOD RADIATIONAL
COOLING SUNDAY NIGHT. WE HAVE SOME PATCHY FROST IN THE GRIDS OVER
THE FAR NE CWA SUNDAY NIGHT WITH LOWS THERE IN THE MID 30S.

.LONG TERM...(TUESDAY THROUGH SATURDAY)
ISSUED AT 319 PM EDT SAT SEP 20 2014

QUIET WEATHER EXPECTED IN THE EXTENDED PERIOD AS THE GREAT LAKES
REGION IS DOMINATED BY STRONG RIDGING AT THE SFC AND ALOFT. WITH DRY
SOUNDINGS AND GENERAL SUBSIDENCE WE SHOULD SEE TEMPERATURE RANGES
GREATER THAN GUIDANCE...WITH MAXES A BIT WARMER AND MINS A BIT
COOLER. MADE SOME TWEAKS IN THAT DIRECTION.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 730 PM EDT SAT SEP 20 2014

SHOWERS STILL AFFECTING OUR EASTERNMOST TERMINALS KLAN AND KJXN WILL
MOVE OUT BY MID EVENING AND CONDITIONS WILL CONTINUE TO IMPROVE TO
VFR AT ALL THE TERMINALS THIS EVENING. HOWEVER THERE IS POTENTIAL
FOR SOME SHOWERS TO REDEVELOP LATE TONIGHT ALONG WITH POTENTIAL FOR
SOME LOW CLOUDS AND PATCHY FOG TO DEVELOP THAT MAY CAUSE CONDITIONS
TO DETERIORATE BACK TO MVFR/IFR DURING THE EARLY MORNING HOURS
SUNDAY. CONDITIONS SHOULD THEN STAY PRIMARILY MVFR THROUGH THE DAY
SUNDAY DUE TO LOW CLOUDS AND SCATTERED SHOWERS.


&&

.MARINE...
ISSUED AT 347 PM EDT SAT SEP 20 2014

CONTINUED WITH THE SCA THROUGH SUNDAY NIGHT. WINDS WILL INCREASE
SUNDAY BUT REMAIN JUST BELOW GALES.


&&

.HYDROLOGY...
ISSUED AT 319 PM EDT SAT SEP 20 2014

RIVER FLOODING IS UNLIKELY GIVEN QPF OVER THE NEXT 24-48 HOURS.
HOWEVER...ANY LOCALLY PERSISTENT CONVECTION MAY LEAD TO SMALL STREAM
AND POOR DRAINAGE ISSUES. PER NCRFC ENSEMBLE QPF RIVER
SCENARIOS...SOME OF THE SMALLER STREAMS AND RIVERS IN SOUTH CENTRAL
LOWER MI MAY APPROACH BANKFULL IF RAINFALL AMOUNTS ACHIEVE THE MAX
EXPECTED /95 PERCENT CONFIDENCE INTERVAL/ QPF THRESHOLD.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 8 AM EDT MONDAY FOR LMZ844>849.

&&

$$

UPDATE...MACZKO
SYNOPSIS...MACZKO
SHORT TERM...93
LONG TERM...OSTUNO
AVIATION...LAURENS
HYDROLOGY...CAS
MARINE...93







USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.