Area Forecast Discussion
Issued by NWS Gaylord, MI

Home | Current Version | Previous Version | Graphics & Text | 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 KAPX 250546
AFDAPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
146 AM EDT TUE AUG 25 2015

.UPDATE...
ISSUED AT 914 PM EDT MON AUG 24 2015

IT IS...AND WILL CONTINUE TO BE...A COOL/DAMP NIGHT. DEEP MOISTURE
AND CYCLONIC CURVATURE AROUND LOW PRESSURE NEARING JAMES BAY
SUPPORTS CONTINUED COOL ADVECTION. A COUPLE OF SMALL SHORTWAVES
CIRCULATING AROUND THE LOW ARE SUPPORTING AREAS OF COLDER CLOUD
TOPS AND ENHANCED PRECIP. ONE IS PREPARING TO EXIT NE LOWER MI.
ANOTHER IS OVER CENTRAL UPPER MI AND S CENTRAL SUPERIOR. WE/RE IN
SOMETHING OF A LULL BETWEEN THESE TWO AT THE MOMENT...AND EVEN SO
THERE ARE PLENTY OF SHRA OUT THERE. EXPECT PRECIP TO BECOME EVEN
MORE WIDESPREAD AGAIN IN NW AND N CENTRAL LOWER MI TOWARD
MIDNIGHT.

&&

.NEAR TERM...(THIS EVENING THROUGH TONIGHT)
ISSUED AT 335 PM EDT MON AUG 24 2015

HIGH IMPACT WEATHER: NONE.

FORECAST CHALLENGE: THE EVOLUTION OF THE LAKE EFFECT(!) RAIN.

OVERVIEW...A 500 MB LOW IS SPINNING JUST NE OF LAKE SUPERIOR AND ITS
ASSOCIATED SFC LOW IS NORTH OF THAT. THE 500 MB LOW HAS SEVERAL
SPOKES OF ENERGY ROTATING AROUND IT, PRODUCING INSTABILITY OVER THE
LAND AND GREAT LAKES. THE MOST EVIDENT IS IN MICHIGAN AS THE US AND
CANADA RADARS SHOW A RAIN SHOWERS ALONG THE CYCLONICALLY ORIENTED
WIND, AND USUALLY ENHANCED AS THE SHOWERS MOVE OVER LAKES MICHIGAN,
HURON, AND SUPERIOR. THE MAIN CHALLENGE WILL BE THE EVOLUTION OF
THESE CHALLENGES.

TONIGHT...IT LOOKS LIKE THE RAIN OVER IN WISCONSIN HAS A DIURNAL
COMPONENT TO IT, BUT ONCE IT HITS LAKE MICHIGAN BEGINS TO PICK UP
MOISTURE AND HEAT. COUPLE THAT WITH THE CURRENTLY +3C 850 MB
TEMPERATURE, AND THE 20C WATER TEMPERATURES, THE 17C DELTA T REALLY
GETS THINGS GOING. SFC BASED CAPES HAVE BEEN BETWEEN 100 AND 300
J/KG SO, THE RAIN SHOWERS HAVE BEEN OPEN CELLULAR RAIN SHOWERS, AS
OPPOSED TO DISCRETE BANDS. THIS IS LIKELY TO CONTINUE AS THE 500 MB
AND SFC LOWS SLOWLY MEANDER TO JUST NE OF ANJ. THE 850 MB
TEMPERATURES LOOK LIKE THEY WILL WARM A BIT OVERNIGHT AS SOME OF THE
WARMER AIR ROTATES AROUND THE SFC LOW AND BEGINS TO BUILD INTO THE
UPPER GREAT LAKES AGAIN. THIS WILL LOWER OUR INSTABILITY TO A DELTA T
OF 13C. SO WILL EXPECT THAT THE RAIN SHOWERS WILL CONTINUE THROUGH
THE NIGHT. WINDS WILL BEGIN TO TURN FROM THE CURRENT WSW PATTERN TO
W BY 00Z, AND WNW AROUND 03Z, AND NW BY 06Z, WHERE IT SHOULD
CONTINUE THROUGH THE REST OF THE NIGHT.

&&

.SHORT TERM...(TUESDAY THROUGH THURSDAY)
ISSUED AT 335 PM EDT MON AUG 24 2015

...CLOUDY/COOL TUESDAY BUT MODERATING TEMPERATURES TO END WEEK...

HIGH IMPACT WEATHER POTENTIAL: MINIMAL OUTSIDE OF ISOLATED
WATERSPOUT POTENTIAL MAINLY ON NORTHERN LAKE HURON.

PATTERN SYNOPSIS/FORECAST: LARGE SCALE PATTERN FEATURES BROAD
TROUGHING IN THE MEAN OVER WESTERN NORTH AMERICA/EASTERN
PACIFIC...WITH A COUPLE MAJOR SHORT WAVE TROUGH FEATURES ROLLING
THROUGH THE MEAN PATTERN.  ONE IS OVER THE NORTHEAST PACIFIC...AND
THE OTHER IS AN UPPER LOW IN THE VICINITY OF LAKE SUPERIOR.
ASSOCIATED 1000MB SURFACE LOW ALONG THE NORTH SHORE OF THE BIG LAKE
(RELATIVELY STRONG BY LATE AUGUST STANDARDS)...COOL AIR MASS OVER
MANITOBA/NORTHWEST ONTARIO GETTING PULLED INTO THE UPPER LAKES ALONG
WITH EXTENSIVE CLOUD COVER (12Z 850MB TEMPERATURES OF +6C/+7C AT
GRB/APX RESPECTIVELY).

LARGE SCALE PATTERN NOT EXPECTED TO CHANGE MUCH AS PACIFIC PATTERN
BECOMES MORE BLOCKED OVER TIME (PROBABLY HELPED ALONG BY REMNANTS OF
TROPICAL CYCLONE "ATSANI" PULLING AWAY FROM JAPAN)...KEEPING
NORTHEAST PACIFIC TROUGH AND RESULTANT -PNA PATTERN IN PLACE WITH
BROAD RIDING DOWNSTREAM ACROSS THE ROCKIES AND ADJACENT PLAINS
STATES.  SLOW MOVING UPPER LOW IMPACTING THE GREAT LAKES EXPECTED TO
OPEN UP BY MIDWEEK AND SHIFT INTO EASTERN CANADA...ALLOWING FLOW TO
FLATTEN AND BECOME MORE ZONAL ACROSS THE PRAIRIE PROVINCES/NORTHERN
PLAINS AND INTO THE GREAT LAKES FOR THE END OF THE WEEK.  CYCLONIC
FLOW WILL BEGIN TO RELAX BY WEDNESDAY AS HIGH PRESSURE BUILDS INTO
THE UPPER/MIDDLE MISSISSIPPI VALLEY.

PRIMARY FORECAST CONCERNS:  EVOLUTION OF SHOWER CHANCES THROUGH
MIDWEEK.

TUESDAY...DAY WILL START OUT WITH UPPER LOW STILL JUST TO THE EAST
OF LAKE SUPERIOR...SURFACE LOW IS EXPECTED TO HAVE LIFTED INTO
NORTHEAST ONTARIO AND DEEP LAYER THERMAL TROUGHING WILL BE JUST EAST
OF THE FORECAST AREA.  SHOWERS SHOULD BE ONGOING ACROSS EASTERN
UPPER AND NORTHWEST LOWER MICHIGAN TUESDAY MORNING...A COMBINATION
OF LAKE PROCESSES AND A SPOKE OF ENERGY ROTATING AROUND PARENT UPPER
LOW.  DIURNAL INFLUENCE EXPECTED TO ALLOW SHOWERS TO BUILD INLAND/
SOUTHEASTWARD AS THE DAY WEARS ON INTO NORTHERN LOWER...WHILE SHOWER
COVERAGE MAY TAPER OFF ACROSS EASTERN UPPER TOWARD MIDDAY.  ANOTHER
COOL AFTERNOON EXPECTED...HIGHS MOSTLY IN THE 55-65 DEGREE RANGE
WHICH IS AROUND 15 DEGREES BELOW AVERAGE.  SHOWER COVERAGE EXPECTED
TO DIMINISH WITH LOSS OF HEATING TUESDAY EVENING...ANTICIPATE
LINGERING SHOWERS (DRIZZLE?) DOWNWIND OF LAKE MICHIGAN OVERNIGHT.

WEDNESDAY...DEEP LAYER CYCLONIC FLOW RELAXES ITS GRIP ON THE UPPER
LAKES FOR MIDWEEK...WITH HIGH PRESSURE BUILDING EAST FROM THE UPPER
MIDWEST.  CLOUDS SHOULD STILL ABOUND WEDNESDAY MORNING...MAYBE SOME
LINGERING LAKE-AIDED DRIZZLE OVER NORTHWEST LOWER.  INCREASING
SUBSIDENCE AND SHRINKING MOIST LAYER SHOULD BRING AN END TO THE
PRECIPITATION THREAT...WITH MORE CLOUDS THAN SUN THOUGH SOME BREAKS
SHOULD DEVELOP.  COUPLE DEGREES WARMER WEDNESDAY BUT STILL LOTS OF
60S FOR HIGHS SO STILL WELL BELOW WHERE WE SHOULD BE.  IF CLOUDS CAN
CLEAR OUT WEDNESDAY NIGHT COULD BE IN FOR A COOL MORNING THURSDAY
WITH LOWS DROPPING INTO THE 40S WITH LIGHT WINDS.  IF THIS OCCURS
COULD ALSO SET UP SOME FOG DEVELOPMENT AS WELL.  WILL BE CAUTIOUSLY
OPTIMISTIC WITH RESPECT TO SKY COVER WEDNESDAY NIGHT AND TREND THE
FORECAST A LITTLE COOLER.

THURSDAY...RISING HEIGHTS AND SHORT WAVE RIDGING ACROSS THE UPPER
LAKES FOR THURSDAY WITH SURFACE HIGH PRESSURE ACROSS MICHIGAN AND
THE OHIO VALLEY.  SO WILL START TO RETURN TO SOMETHING MORE TYPICAL
FOR LATE SUMMER...HIGHS GETTING BACK INTO THE LOWER-MID 70S WITH
MORE SUN (POSSIBLY AFTER SOME EARLY FOG).

&&

.LONG TERM...(THURSDAY NIGHT THROUGH MONDAY)
ISSUED AT 335 PM EDT MON AUG 24 2015

LOOKING TO BE A FAIRLY QUIET EXTENDED PERIOD. AS MENTIONED IN
PREVIOUS DISCUSSION...MOISTURE SUPPORT FOR WEEKEND RAIN CHANCES IS A
LITTLE UNDERWHELMING...BUT WILL CONTINUE WITH THE LOW CHANCE POPS
FOR FRI/SAT. BETTER SUPPORT FOR SHOWERS LOOKS TO BE FOR THE NORTHERN
PORTIONS OF THE FORECAST AREA. NOT MUCH ACTIVITY AFTER SATURDAY
GOING INTO THE WORK WEEK...ALTHOUGH THERE IS A DECENT SHORTWAVE THAT
IS IN THE VICINITY LATE IN THE WEEKEND. RIGHT NOW THERE IS PRETTY
SOLID AGREEMENT OF THIS REMAINING TO OUR SOUTH...BUT SHOULD THAT
CHANGE WE COULD SEE SOME ADDITIONAL RAIN CHANCES. TEMPERATURES WILL
WARM STEADILY...FROM ABOUT NORMAL FRIDAY TO WELL ABOVE NORMAL BY
MONDAY.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 143 AM EDT TUE AUG 25 2015

...STILL GUSTY AND COOL WITH LAKE EFFECT RAINS...

DEEP LOW PRESSURE WILL DRIFT INTO WESTERN QUEBEC TODAY AND TONIGHT
WITH WESTERLY WINDS BRINGING CONTINUED LAKE EFFECT RAINS TO MAINLY
NW LOWER. THESE RAINS HAVE BEEN ABLE TO MAKE IT OVER INTO APN VIA
SFC TROUGHS ROTATING AROUND THE LOW PRESSURE. WE WILL HAVE ONE MORE
TROUGH TO SWING THROUGH AROUND MID DAY TODAY...ENHANCING THE
RAINS...AND ALSO SWINGING GUSTY WEST WINDS MORE OUT OF THE NW THIS
AFTERNOON. LIGHT LAKE EFFECT CONTINUES ACROSS NW LOWER TONIGHT.
MINIMAL RESTRICTIONS TO VSBY...ALTHOUGH RAINS SHOULD BE A BIT MORE
DRIZZLY IN NATURE...AND MINOR RESTRICTIONS ARE POSSIBLE. CIGS ARE
STARTING TO CRASH...AND WILL DO SO THROUGH THE MORNING. WILL BE
OVC MVFR FOR MOST...IF NOT ALL OF THE TAF PERIOD AFTER A FEW
HOURS/TOWARD DAYBREAK.

&&

.MARINE...
ISSUED AT 335 PM EDT MON AUG 24 2015

TONIGHT THROUGH WEDNESDAY...SMALL CRAFT ADVISORY CONDITIONS ARE
EXPECTED TO CONTINUE THROUGH TUESDAY, BEFORE GRADUALLY DIMINISHING
TUESDAY NIGHT AND INTO WEDNESDAY. THE SFC LOW PRODUCING THE WINDS
WILL MOVE FROM NORTH OF LAKE SUPERIOR TODAY, TO JUST NORTHEAST OF
SAULT STE. MARIE BY TUESDAY MORNING(12Z). AS THE LOW MOVES NE INTO
JUST SOUTH OF JAMES BAY, THE GRADIENT WILL REMAIN TIGHT, BUT THE
WIND DIRECTION WILL BE NORTHWEST OVER THE REGION. TUESDAY NIGHT,
HIGH PRESSURE SHOULD BUILD INTO THE REGION, BUT THE GRADIENT WILL
REMAIN TIGHT OVERNIGHT. THE WINDS ON WEDNESDAY WILL BEGIN TO COME
DOWN ON WEDNESDAY AS HIGH PRESSURE BUILDS IN. THE WAVES WILL SUBSIDE
AS WELL, BUT IT MAY TAKE A FEW HOURS MORE AFTER THE WIND DIMINISHES
THROUGH THE DAY.


&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...BEACH HAZARDS STATEMENT UNTIL 6 AM EDT EARLY THIS MORNING FOR
     MIZ016-019>021-025-031.

LH...SMALL CRAFT ADVISORY UNTIL 6 AM EDT EARLY THIS MORNING FOR
     LHZ345>349.

LM...SMALL CRAFT ADVISORY UNTIL 6 AM EDT EARLY THIS MORNING FOR
     LMZ323-341-346.

     SMALL CRAFT ADVISORY UNTIL 2 PM EDT THIS AFTERNOON FOR LMZ342-
     344-345.

LS...SMALL CRAFT ADVISORY UNTIL 6 AM EDT EARLY THIS MORNING FOR
     LSZ322.

     SMALL CRAFT ADVISORY UNTIL 2 PM EDT THIS AFTERNOON FOR LSZ321.

&&

$$

UPDATE...JAZ
NEAR TERM...JSL
SHORT TERM...JPB
LONG TERM...ALM
AVIATION...SMD
MARINE...JSL


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