Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 040547
AFDAPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
147 AM EDT TUE AUG 4 2015

.UPDATE...
ISSUED AT 1022 PM EDT MON AUG 3 2015

SPOTTY SHOWERS CONTINUE TO DRIFT THRU OUR CWA LATE THIS EVENING...
DRIVEN BY DEEP CYCLONIC FLOW AND MODEST LOW LEVEL MOISTURE BEHIND
THE COLD FRONT THAT PUSHED THRU EARLY THIS MORNING. ANY ISOLD
THUNDER THAT DEVELOPED DURING LATE AFTERNOON/EARLY EVENING HAS
ENDED...AND IS UNLIKELY TO REDEVELOP OVERNIGHT WITH LOSS OF
DIURNAL INSTABILITY. HAVE REMOVED ISOLD THUNDER FROM THE OVERNIGHT
FORECAST...BUT LEFT SMALL CHANCES OF SHOWERS FOR THE BALANCE OF
THE NIGHT.

&&

.NEAR TERM...(THIS EVENING THROUGH TONIGHT)
ISSUED AT 345 PM EDT MON AUG 3 2015

HIGH IMPACT WEATHER: NONE

SHORTWAVE OVER SOUTHERN ONTARIO AND COLD FRONT DRAPED ACROSS
NORTHERN MICHIGAN THIS AFTERNOON HELPING TO DRIVE SOME SHOWER AND
THUNDERSTORM DEVELOPMENT. CAPE VALUES STARTED OUT AROUND 500J/KG AT
12Z BUT WILL DECREASE DURING THE DAY WITH COOLER DRIER AIR MOVING
IN. PRETTY SCATTERED AT THIS TIME AND DIURNALLY DRIVEN AND EXPECT
COVERAGE TO DECREASE WITH THE LOSS OF DAYTIME HEATING LATER THIS
EVENING. OTHERWISE...MASS OF CLOUDS IN UPPER COLD POOL WILL MOVE IN
TONIGHT. 850MB TEMPS DROP INTO THE SINGLE DIGITS OVERNIGHT...SO
COULD BE A LAKE EFFECT COMPONENT TO SHOWERS TOWARD MORNING.

&&

.SHORT TERM...(TUESDAY THROUGH THURSDAY)
ISSUED AT 345 PM EDT MON AUG 3 2015

PRIMARY FORECAST CHALLENGE: WATERSPOUTS ON TUESDAY.

(8/4)TUESDAY...MODELS PEG ANOTHER SFC TROUGH TO MOVE THROUGH THE
FORECAST AREA IN THE MORNING, TO BE CLEARING THE FORECAST AREA BY
00Z. THE COOLEST AIR LOOKS TO MOVE INTO THE FORECAST AREA (BASED ON
THE 850 MB TEMPERATURES) DURING THE AFTERNOON. THE 850 MB
TEMPERATURES FALL TO +5C ON THE GFS AND +7C ON THE ECMWF. THE WATER
TEMPERATURES IN N LAKE MICHIGAN ARE +20C, SO WE HAVE ENOUGH FOR LAKE
ENHANCED/EFFECT SHOWERS OVER THE NORTHERN PART OF LAKE MICHIGAN AND
NW LOWER. KEPT THE POPS IN THE CHANCE CATEGORY FOR THE AFTERNOON AS
THE SHOWERS ARE EXPECTED TO BE VERY LIGHT AND SCATTERED.

NOW FOR THE WATERSPOUTS...AM HIGHLY UNDERWHELMED BY THE 850 MB
TEMPERATURES. WE ARE JUST GETTING INTO THE NOMOGRAM WITH THE DELTA
TS AT THE MOST (THIS IS ON THE GFS) 15C WHICH THE LOWER BOUND, FOR
SOMETHING UNDER AN UPPER LOW SCENARIO. THE ECMWF AND NAM HAVE ABOUT
13C. SO AM NOT EXPECTING ANYTHING. IT WOULD PROBABLY BE A 1 OR 2 ON
THE SWI BY SZILAGYI. SO IT`S NOT OUT OF THE REALM OF POSSIBILITIES,
BUT AM NOT EXPECTING ANY REPORTS.

(8/5)WEDNESDAY...HEIGHTS BUILD AT 500 MB AND THE 850 MB TEMPERATURES
WARM TO AROUND 8C BY THE AFTERNOON, AND WITH THE SFC HIGH BUILDING
INTO THE REGION, IT LOOKS LIKE IT MAY BE PARTLY SUNNY AND DRY. THIS
WILL CONTINUE INTO THE NIGHT AS WELL, SORT OF. THE ECMWF AND THE GFS
ARE AT ODDS AS TO WHETHER A SFC LOW MAKES IT INTO THE FORECAST AREA.
THE ECMWF HAS IT IN THE BOUNDARY WATERS AT 12Z, WHILE THE GFS HAS IT
MOVING OUT OF THE IOWA WITH RAIN GETTING INTO THE SW COUNTIES. WILL
LEAVE THE NIGHT DRY FOR NOW.

(8/6)THURSDAY...THE GFS CONTINUES TO PUSH THE LOW ALONG THE
MICHIGAN/INDIANA BOARDER WITH THE RAIN AFFECTING AREAS SOUTH OF M-
32. THE ECMWF HAS LIGHT RAIN IN UPPER MICHIGAN AS THE SFC LOW MOVES
TO W UPPER. HAVE SOME SLIGHT CHANCE POPS FOR THE RAIN ALONG THE
SOUTHERN BORDER. WILL SEE HOW THIS WORKS.

&&

.LONG TERM...(THURSDAY NIGHT THROUGH MONDAY)
ISSUED AT 345 PM EDT MON AUG 3 2015

CHANCE POPS CONTINUE THROUGH THE WEEKEND WITH CONTINUED UNCERTAINTY
ON THE EVOLUTION OF H5 RIDGING AND WEAK SHORTWAVES MOVING THROUGH.
THE EASTERN EXTENT OF THE RIDGE WILL INFLUENCE WHERE THE SHORTWAVE
MOVES...AS WELL AS OUR PRECIP CHANCES. SHOULD BE ABLE TO GET A
BETTER HANDLE ON THE PATTERN EVOLUTION IN THE COMING DAYS.
TEMPERATURES WILL BE BELOW NORMAL TO START THE PERIOD...WARMING BACK
TO NORMAL BY THE WEEKEND.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 138 AM EDT TUE AUG 4 2015

...VFR...

DEEP LOW PRESSURE WILL SLOWLY DRIFT THROUGH QUEBEC TODAY AND
TONIGHT. SEVERAL DISTURBANCES ALOFT WILL PERIODICALLY DRIFT THROUGH
NRN MICHIGAN...WITH A SFC TROUGH CROSSING THE REGION. SCATTERED TO
NUMEROUS SHOWERS OUT AHEAD OF THIS TROUGH WILL AFFECT MAINLY
TVC/PLN/APN. THESE SHOWERS WILL BE ENHANCED THIS MORNING ACROSS
NW LOWER...DUE TO COLD AIR OVER RELATIVELY WARM LAKE MICHIGAN. NO
RESTRICTIONS TO VSBY EXPECTED...WITH JUST A SMALL CHANCE AT MVFR
CIGS AT PLN. WINDS WILL MAINLY BE WNW WITH AFTERNOON GUSTS
15-20KTS. THE ATMOSPHERE DRIES OUT TONIGHT WITH MINIMAL CHANCES
FOR ADDITIONAL SHOWERS.

&&

.MARINE...
ISSUED AT 138 AM EDT TUE AUG 4 2015

AN OVERALL WESTERLY WIND WILL BE COMMON ACROSS THE NEARSHORES AGAIN
TODAY WITH AFTERNOON GUSTS TO 20 KNOTS...LOW END ADVISORY GUSTS AT
WHITEFISH BAY AND AROUND PRESQUE ISLE LIGHT. CURRENT ADVISORY IN
THESE AREAS LOOKS FINE...BUT MAY HAVE TO BE EXTENDED INTO THE
EVENING. MORE DISTURBANCES ALOFT WILL BRING PERIODS OF LIGHT
RAIN SHOWERS TODAY AS WELL...ENHANCED BY OVERLAKE INSTABILITY
THIS MORNING. CHANCES FOR WATERSPOUTS INCREASE AS WELL OVER THIS
TIME...AS A SFC TROUGH SWINGS OVER LAKE MICHIGAN...BUT CONDITIONS
ARE NOT EXACTLY PRIME. HIGH PRESSURE THEN SLIDES IN FOR WEDNESDAY
AND THURSDAY...AND DESPITE ADDITIONAL DISTURBANCES...AIR MASS TOO
DRY FOR RAIN. WIND SPEEDS TO REMAIN BELOW ADVISORY CRITERIA FOR
THE NEXT SEVERAL DAYS.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...SMALL CRAFT ADVISORY FROM NOON TODAY TO 8 PM EDT THIS EVENING
     FOR LHZ347-348.

LM...NONE.
LS...SMALL CRAFT ADVISORY FROM NOON TODAY TO 8 PM EDT THIS EVENING
     FOR LSZ321-322.

&&

$$

UPDATE...MLR
NEAR TERM...KJF
SHORT TERM...JSL
LONG TERM...ALM
AVIATION...SMD
MARINE...SMD


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