Area Forecast Discussion
Issued by NWS Grand Rapids, MI

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
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 171135
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
735 AM EDT FRI OCT 17 2014

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 326 AM EDT FRI OCT 17 2014

WE GET A BRIEF WARM UP TODAY JUST AHEAD OF THE COLD FRONT THAT
COMES THROUGH BY MIDDAY. ONCE THE FRONT COMES THROUGH SHOWERS AND
ISOLATED THUNDERSTORMS ARE EXPECTED FROM MID AFTERNOON INTO MID
EVENING. OVERNIGHT INTO MID AFTERNOON SATURDAY SHOWERS WILL MOSTLY
BE NEAR AND WEST OF US-131 BUT IT WILL BE BREEZY AND MUCH COLDER.
TEMPERATURES STRUGGLE TO MAKE THE UPPER 40S DURING THE AFTERNOON.
SKIES SHOULD CLEAR SATURDAY NIGHT ALLOW FOR A WIDESPREAD FREEZE
ACROSS THE AREA. ANOTHER SYSTEM MOVING THROUGH THE GREAT LAKES
WILL BRING THE CHANCE OF SHOWERS BACK TO THE AREA MONDAY.

&&

.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 326 AM EDT FRI OCT 17 2014

THE BIG STORY IS THE COLD AIR COMING IN THIS EVENING WITH SHOWERS
AND ISOLATED THUNDERSTORMS. ONCE THE COLD AIR HAD BECOME
ENTRENCHED ACROSS THE ARE THE LAKE EFFECT SHOWERS ARE EXPECTED TO
BE CONFINED TO AREAS WEST OF US-131 LATER TONIGHT INTO SATURDAY
AFTERNOON. A FREEZE IS LIKELY SATURDAY NIGHT INTO SUNDAY MORNING
AS SKIES CLEAR AND WINDS BECOME LIGHT.

THE SYSTEM COMING THROUGH THE AREA THIS AFTERNOON INTO TONIGHT
LOOKS IMPRESSIVE ON THE WATER VAPOR LOOPS AND BASED ON ALL OF THE
MODES HAD STRONG DYNAMICS WITH A GOOD 500 MB COLD CORE TO HELP THE
CAUSE. IN FACT VERTICAL TOTAL REACH NEAR 27 DEGREES AS THE COLD
CORE UPPER LOW CROSSES THE AREA LATE THIS AFTERNOON INTO EARLY
THIS EVENING. 850 MB LI ARE NEAR ZERO AND THE TQ INDEX IS NEAR 18
DEGREES. THERE IS EVEN A LITTLE WEAK CAPE ON MODEL SOUNDING DURING
THAT TIME FRAME. THE 21Z SPC SREF THUNDERSTORM PROBABILITY
SUGGESTS THE GREATEST RISK OF THUNDERSTORMS THIS AFTERNOON IS
MOSTLY EAST OF LANSING. THE NAM12 THUNDERSTORM PROBABILITY REACHES
NEAR 50 PCT OVER BETWEEN 5 PM AND 8 PM MOVER MOST OF OUR SOUTHERN
AND CENTRAL CWA. AS A RESULT I ADDED ISOLATED THUNDERSTORMS TO THE
GRID FORECAST FROM LATE THIS AFTERNOON INTO THIS EVENING OVER THE
EASTERN CWA (WHERE THE INSTABILITY IS GREATEST.

OTHERWISE AS I SUGGESTED YESTERDAY WE HAVE DEEP MOISTURE ALONG THE
FRONTAL TROUGH SO THERE SHOULD BE WIDESPREAD SHOWERS AS THE COLD
AIR STARTS COMING IN LATER THIS AFTERNOON. AFTER 10 PM OR SO WINDS
IN THE BOUNDARY LAYER BECOME MORE NORTHERLY SO THE SHOWERS WILL
MOSTLY BE NEAR THE LAKE SHORE. WHILE THERE IS NOT MUCH LIFT IN
THE DGZ THERE IS CONSIDERABLE LIFT IN THE NEAR 0C LAYER WHICH IS
SATURATED. THAT IS MORE THAN ENOUGH TO SET UP SHOWERS AS IS
TYPICAL IN THIS SORT OF SET UP IN THE EARLY TO MID FALL. SO I HAVE
CONDITIONAL POPS NEAR THE LAKE SHORE INTO LATE MORNING SATURDAY.

SKIES SHOULD CLEAR AS MID LEVEL WARM AIR TRIES TO COME IN SATURDAY
NIGHT. THAT WILL ALLOW MOST LOCATIONS EXCEPT NEAR THE LAKE SHORE
TO SEE LOWS BELOW FREEZING.

.LONG TERM...(SUNDAY NIGHT THROUGH THURSDAY)
ISSUED AT 326 AM EDT FRI OCT 17 2014

THE WEATHER FOR THE LONG TERM CAN BE CATEGORIZED INTO TWO DIFFERENT
PERIODS. THE FIRST THREE OR FOUR PERIODS WILL BE A BIT UNSETTLED
ACROSS THE AREA AND TRENDING COOLER. THE UPPER TROUGH/LOW WILL
REMAIN IN CONTROL OF THE WX FOR THE AREA. WE WILL SEE ONE LAST SHORT
WAVE IN THE SERIES DROP SE ACROSS THE AREA. THIS WILL GIVE THE AREA
ONE MORE DECENT SHOT OF RAIN SHOWERS MAINLY ON MON AND INTO MON
NIGHT.

BEGINNING ON TUE...THROUGH THE REST OF THE PERIOD WILL FEATURE DRIER
CONDITIONS AND MILDER TEMPERATURES. THERE COULD BE A FEW LEFT OVER
SHOWERS ON TUE MORNING ACROSS THE SE PORTION OF THE FCST AREA. THESE
WILL MOVE OUT QUICKLY AND THEN THE AREA WILL COME UNDER CONTROL OF
HIGH PRESSURE. AN UPPER RIDGE WILL BUILD ACROSS THE ROCKIES THIS
COMING WEEKEND...AND WILL GRADUALLY BUILD EAST INTO EARLY NEXT WEEK.
WE SHOULD SEE THE EFFECTS FROM THIS RIDGE STARTING TUE AFTERNOON.

THIS RIDGE WILL REMAIN IN CONTROL AS THE PATTERN AMPLIFIES A BIT AND
ALMOST BECOMES AN OMEGA BLOCK STRETCHING FROM THE ERN PACIFIC TO THE
WRN ATLANTIC. WE WILL SEE A DRY PERIOD FROM TUE AFTERNOON THROUGH
THE END OF THE PERIOD AND LIKELY BEYOND. TEMPS WILL MODIFY...AND
SHOULD WARM BACK UP TO AROUND 60F TOWARD NEXT THU.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 735 AM EDT FRI OCT 17 2014

THERE IS A CLEARING LINE THAT IS JUST NOW MOVING NO SHORE. THIS
WILL MOVE EAST AND CLEAR ALL OF THE TAF SITES OUT BY 15Z. A HOLE
IN THE CLOUDS OVER GRR WILL BRIEFLY FILL IN AS ANOTHER BAND OF LOW
CLOUDS MOVES IN BUT THIS BAND IS NARROW AND IS ACTUALLY IS THE
BACK EDGE OF THE LOWER CLOUDS. BY 15Z THIS SHOULD BE EAST OF ALL
OF OUR TAF SITES. SO FROM 15Z TILL THE FRONTAL SHOWERS MOVE IN
AFTER 21Z... I EXPECT MOSTLY VFR CONDITIONS. IT WILL BE BREEZE
THOUGH. THE SHOWERS SHOULD GIVE ALL TAF SITES 3 TO 5 HOURS OF
SHOWERS...THEN IT WILL BECOME MOSTLY CLOUDY WITH MVFR CEILINGS.


&&

.MARINE...
ISSUED AT 326 AM EDT FRI OCT 17 2014

I CONTINUED THE SMALL CRAFT ADVISORY FOR THIS MORNING AND THIS
AFTERNOON AND I UPGRADED THE GALE WATCH TO A WARNING AND EXPANDED
IT SOUTH THROUGH THE ENTIRE NEAR SHORE.  I WILL ADMIT THE WINDS IN
THE BOUNDARY LAYER ARE MARGINAL FOR GALES TONIGHT INTO SATURDAY BUT
WITH THE STRENGTH OF THIS SYSTEM AND THE AMOUNT OF COLD AIR... IT
WOULD SEEM MORE THAN REASONABLE TO HAVE A GALE WARNING OVER THE
ENTIRE NEAR SHORE TONIGHT INTO SATURDAY EVEN SO.


&&

.HYDROLOGY...
ISSUED AT 326 AM EDT FRI OCT 17 2014

RIVERS ARE ON THE HIGH SIDE BUT EXPECTED PRECIPITATION THROUGH THE
WEEKEND IS MOSTLY UNDER A QUARTER INCH SO THERE SHOULD BE NO SIGNIFICANT
IMPACTS.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR LMZ844>849.

     GALE WARNING FROM 8 PM THIS EVENING TO NOON EDT SATURDAY FOR
     LMZ844>849.

&&

$$

SYNOPSIS...WDM
SHORT TERM...WDM
LONG TERM...NJJ
AVIATION...WDM
HYDROLOGY...WDM
MARINE...WDM





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