Area Forecast Discussion
Issued by NWS Gaylord, MI

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000
FXUS63 KAPX 311659
AFDAPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
1259 PM EDT FRI JUL 31 2015

.UPDATE...
ISSUED AT 1256 PM EDT FRI JUL 31 2015

SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS HAVE BEEN ABLE TO
FIRE OFF ALONG AND AHEAD OF THE SFC TROUGH. MOISTURE HAS POOLED
AHEAD OF THIS FEATURE WITH DEW POINTS HIGHER THAN ANTICIPATED AND
THE TEMPERATURES HAVE SPIKED A COUPLE OF DEGREES HIGHER. COMBINE
THOSE SMALL/FINITE ALTERATIONS WITH STEEPENING LAPSE RATES ON THE
TROUGH...AND THAT IS PLENTY ENOUGH. WILL SWEEP THESE SHOWERS EAST
THROUGH MID AFTERNOON...AND WILL BE KEEPING AN EYE ON UPSTREAM
AREAS OF CENTRAL UPPER AND NE WISCONSIN FOR THE POTENTIAL FOR
THEIR SHOWERS TO MAKE IT ACROSS LAKE MICHIGAN...WITH SOME ISOLATED
ACTIVITY AROUND NW LOWER.

UPDATE ISSUED AT 945 AM EDT FRI JUL 31 2015

IMPACT WEATHER: ELEVATED FIRE DANGER INTO EARLY THIS EVENING.

SYNOPTIC PATTERN/OBSERVATIONS/EXPECTATIONS:

MORNING ANALYSIS...DEEP LOW PRESSURE STILL SWIRLING OVER HUDSON BAY
WITH SEVERAL SHORTWAVE/VORTICITY MAXIMA ROTATING ALONG IT`S SRN
BASE. ONE OF THE ASSOCIATED SFC TROUGHS IS WORKING INTO EASTERN
UPPER RIGHT NOW (13Z)...SEEN ON AREA OBSERVATIONS AS WELL AS
SATELLITE AS A BAND OF CLOUDS. ANOTHER SFC TROUGH STRETCHED FROM SW
ONTARIO BACK THROUGH CENTRAL MANITOBA. ALTHOUGH THE PRESENCE OF EACH
TROUGH BRINGS WITH IT LOW LEVEL CONVERGENCE...IT`S REALLY NOT THE
DRIVING FORCE THAT PRODUCES SHOWERS AND POCKETS OF THUNDERSTORMS.
THAT PRECIPITATION NOW ALL RESIDES ACROSS ONTARIO...WITHIN A SWATH
OF SLIGHT INCREASE IN THETA-E...WEAK -DIVQ AND AXIS OF STEEPER LAPSE
RATES ALOFT. ALL MODEL DATA SUGGESTING SOME SORT OF LIGHT PRECIP
EXPECTED TO ROLL THROUGH BETWEEN 15-21Z...MAINLY ACROSS THE NRN HALF
OF THE CWA. HOWEVER...APPEARS AS THOUGH MODELS ARE LOCKING IN ON
DEVELOPING SHOWERS FROM OVERLAKE SBCAPE...AND THEN SHOVING THAT
CONVECTION INLAND. FIRST OF ALL...THERE IS NO CONVECTION LIKE MODELS
SAY THERE SHOULD BE...SECOND OF ALL...MOST MODELS HAVE TOO MUCH SFC
BASED MOISTURE IN GENERATING THAT SBCAPE. THUS...DO NOT EXPECT ANY
SHOWERS THROUGH THE DAY. WILL SEE SOME ADDED CLOUD ASSOCIATED WITH
THE SFC TROUGHING...AND WITH DIURNAL HEATING AND LIFTING OF OUR
SOMEWHAT LIMITED OVERALL MOISTURE. MOST AREAS WILL SEE PLENTY OF
SUN...WITH ANOTHER DAY OF FAIRLY DEEP MIXING. NOT AS WINDY TODAY (UP
TO 25 MPH...RATHER THAN YESTERDAYS 35 MPH)...BUT WILL STILL HAVE
ELEVATED FIRE DANGER DUE TO THE GUSTS AND WARM TEMPERATURES AND A
LACK OF RECENT RAINFALL.

WILL HAVE TO WATCH FOR A SMALL SHOWER POSSIBILITY TONIGHT...AS AN
ADDITIONAL WAVE WORKS DOWN THE BACKSIDE OF THE HUDSON BAY LOW
PRESSURE...CONTINUING A PROCESS OF LOWERING HEIGHTS AND STEEPENING
LAPSE RATES ALOFT. THIS MAY BRING THE SRN ONTARIO AXIS OF SLIGHTLY
HIGHER THETA-E DOWN INTO NRN MICHIGAN. AM NOT ENTIRELY CONFIDENT IN
THIS EITHER...AND AS OF NOW...ONLY SLIGHT CHANCES FOR A RAIN SHOWER
ARE FORESEEN. MORE ON THIS LATER THIS AFTERNOON.

&&

.NEAR TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 444 AM EDT FRI JUL 31 2015

...FEW SHOWERS POSSIBLE IN SPOTS TODAY/TONIGHT...

HIGH IMPACT WEATHER POTENTIAL: ELEVATED FIRE DANGER THIS AFTERNOON.

PATTERN SYNOPSIS/FORECAST: FAIRLY TIGHT PRESSURE GRADIENT REMAINS
ACROSS THE GREAT LAKES EARLY THIS MORNING...SURFACE TROUGH LIES
ACROSS NORTHWEST ONTARIO/NORTHERN MINNESOTA.  SEVERAL SHORT WAVE
TROUGHS WITHIN NORTHWEST FLOW ALOFT PER WATER VAPOR IMAGERY...ONE
LOCATED EAST OF GEORGIAN BAY WITH AN ASSOCIATED POTENTIAL VORTICITY
AXIS THAT EXTENDS BACK ACROSS LOWER MICHIGAN/WESTERN UPPER MICHIGAN/
NORTHWEST ONTARIO.  WITHIN THIS AXIS IS ANOTHER VORTICITY CENTER
CROSSING EASTERN UPPER MICHIGAN...AND A BETTER DEFINED SHORT WAVE
TROUGH MOVING INTO FAR NORTHWEST MINNESOTA.  THESE VARIOUS WAVES
RESULTING IN A BROKEN AREA OF (DIMINISHING) SHOWERS TRACKING
SOUTHEAST FROM NORTHWEST ONTARIO AND ACROSS LAKE SUPERIOR TOWARD THE
UPPER PENINSULA.  NOT MUCH CLOUD COVER ACROSS THE FORECAST AREA
EARLY THIS MORNING...BETTER CLOUD/SHOWER COVERAGE CLOSER TO THE
MINNESOTA SHORT WAVE TROUGH OVER NORTHEAST MINNESOTA/NORTHWEST
ONTARIO.

SHORT WAVE TROUGH MOVING THROUGH MINNESOTA EARLY THIS MORNING WILL
CROSS MICHIGAN DURING THE DAY TODAY BEFORE TRACKING INTO THE LOWER
GREAT LAKES TONIGHT.  THIS WILL BE FOLLOWED BY ANOTHER QUICK MOVING
SHORT WAVE/MID LEVEL JET STREAK OVERNIGHT.  WEST-NORTHWEST BOUNDARY
LAYER FLOW WILL PERSIST BETWEEN LOW PRESSURE OVER HUDSON BAY AND A
NARROW HIGH PRESSURE RIDGE OVER THE MIDWEST.

PRIMARY FORECAST CONCERNS: IMPACTS OF PASSING SHORT WAVE TROUGHS.
ELEVATED FIRE DANGER.

TODAY...WATER VAPOR IMAGERY TRENDS SUGGEST UPWARD MOTION FIELD
ASSOCIATED WITH APPROACHING SHORT WAVE TROUGH WILL BE SPREADING INTO
NORTHERN PORTIONS OF THE FORECAST AREA SHORTLY AFTER DAYBREAK...BUT
INITIALLY LOOKS LIKE THINGS MAY BE QUIET TO START THE DAY WITH SOME
MID CLOUDS HEADED TOWARD EASTERN UPPER.  SUSPECT LIKE YESTERDAY...
QUESTION FOR TODAY IS WHETHER ENOUGH DESTABILIZATION WILL TAKE PLACE
TO ALLOW FOR NEW CONVECTIVE DEVELOPMENT.  THINK THE IDEA OF SOME
DEVELOPMENT ACROSS THE NORTHERN THIRD OR SO OF THE FORECAST AREA IS
NOT UNREASONABLE...AT LEAST FROM A PROBABILISTIC STANDPOINT...
CLOSER TO THE TRACK OF THE PASSING SHORT WAVE TROUGH AND WHERE LOW
LEVEL MOISTURE LIKELY TO REMAIN A LITTLE HIGHER.  NOT CONVINCED YET
THAT THIS IS GOING TO BE A HUGE DEAL BUT THERE IS PROBABLY ENOUGH
POTENTIAL THERE TO JUSTIFY SOME MEASURABLE POPS.  WINDS WILL BE A
LITTLE GUSTY AGAIN WITH DEEP MIXING BUT NOT TO THE EXTENT OF
THURSDAY`S GUSTS (MORE IN THE 20-25MPH RANGE THIS AFTERNOON).  DEEP
MIXING SHOULD ALSO PUSH TEMPERATURES BACK INTO THE 80S ACROSS MUCH
OF NORTHERN LOWER THIS AFTERNOON.  LIKE THURSDAY...THE COMBINATION
OF WARM TEMPERATURES/GUSTY WINDS/RECENT DRYNESS WILL LEAD TO
ELEVATED FIRE DANGER ONCE AGAIN THIS AFTERNOON.

TONIGHT...SECONDARY SHORT WAVE TROUGH/JET STREAK FORECAST TO ARRIVE
LATER TONIGHT...CAN ENVISION THIS FEATURE DRAGGING IN AN AREA OF
SHOWERS ALONG WITH IT...AND THE POSSIBILITY THAT SOME NOCTURNAL
INSTABILITY OVER THE WARMING LAKES MICHIGAN/HURON (GETTING TO THAT
TIME OF YEAR) WILL CONTRIBUTE AS WELL IN GENERATING SHOWERS AND
PERHAPS A THUNDERSTORM.

&&

.SHORT TERM...(SATURDAY THROUGH SUNDAY NIGHT)
ISSUED AT 444 AM EDT FRI JUL 31 2015

PRIMARY FORECAST CHALLENGE: PERIODS OF LIGHT SHOWER POTENTIAL
THROUGH THE WEEKEND.

FORECAST DETAILS...USUALLY I BREAK THIS INTO THE SPECIFIC DAYS, BUT
FOR THE MOST PART, THE IDEA FOR SATURDAY AND SUNDAY ARE BASICALLY
THE SAME. AS THE HUDSON BAY 500 MB LOW SITS, WITH VARIOUS SPOKES OF
MOISTURE/ENERGY ROTATING AROUND THE LOW PRODUCING DIURNAL
CLOUDINESS, AND AT TIME DIURNAL SHOWERS. AS WAS SEEN YESTERDAY
(THURSDAY) THE SHOWERS FIRED UP IN THE DIURNAL CLOUDS, ONLY TO FADE
AWAY OVERNIGHT. BASED ON THE CURRENT MODEL OUTPUT, SATURDAY LOOKS
LESS SHOWERY THAN SUNDAY AS THE INITIAL IMPULSE (ON SATURDAY) TO
ROTATES INTO THE UPPER GREAT LAKES HAS LITTLE TO NO INSTABILITY WITH
THE ML AND SFC CAPES <100 J/KG. SO WILL EXPECT A DAY SIMILAR TO
THURSDAY AS THE CLOUD STREETS GENERATE DOWN LAKE WITH A FEW
CONGEALING INTO SOME MINOR SHOWERS.

FOR SUNDAY, A WEAK SFC TROUGH LOOKS TO BE SUPPORTING THE 500 MB
SHORTWAVE TROUGH, WHICH BEGINS TO PUSH THE WARM AIR NORTHEAST INTO
THE FORECAST AREA. MODEL ML CAPES LOOK TO BE AROUND 600 J/KG WITH A
MLCINH OF 40 J/KG. SO IF THE WARM FRONT CAN KICK SOMETHING OFF THERE
COULD BE THUNDER, BUT BASED ON THESE PROFILES WILL EXPECT A LITTLE
MORE ORGANIZED SHOWER ACTIVITY. CAN THERE BE THUNDER? SURE, BUT IT
WILL BE LESS LIKELY THAN THE RAIN SHOWERS.

&&

.LONG TERM...(MONDAY THROUGH THURSDAY)
ISSUED AT 444 AM EDT FRI JUL 31 2015

EXTENDED (MONDAY THROUGH THURSDAY)...IT`S BEGINNING TO LOOKS AS IF
THE TROUGH OVER HUDSON BAY MAY BREAKDOWN AFTER THURSDAY AS THE WHOLE
PATTERN WITH THE GULF OF ALASKA LOW BEGINNING TO BREAK INTO PIECES,
WITH ONE PIECE ENDING UP IN THE PAC NW. THIS LOOKS TO PUSH THE RIDGE
TO THE EAST, AND THE HUDSON BAY LOW BEGINS TO MOVE EAST INTO THE
CANADIAN MARITIMES. HOWEVER, FOR MONDAY THROUGH WEDNESDAY, THE
PATTERN IS A SLOW MOVING COOL, SOMEWHAT WET PATTERN. I SAY SOMEWHAT
WET, DUE TO THE FACT THAT IT LOOKS LIKE A MID FALL COOL RAIN SHOWER
PATTERN, WITH A LITTLE THROWN IN AT TIMES. THE CIPS ANALOGS SHOW
BELOW NORMAL TEMPERATURES THROUGH THE PERIOD, WITH THE THREE DAY
MEAN PRECIPITATION AMOUNTS OF 0.25". SO BASED ON THAT AND THE DRYNESS
OF THE ECMWF THROUGH MOST OF THE PERIOD, WE BARELY GET TO 30% CHANCE
FOR MEASURABLE RAIN ON ANY DAY.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 644 AM EDT FRI JUL 31 2015

MOSTLY PREVAILING VFR CONDITIONS TODAY...SOME GUSTY WINDS THROUGH
THE AFTERNOON HOURS ALONG WITH SCATTERED SHOWERS AROUND PLN/APN.


&&

.MARINE...
ISSUED AT 444 AM EDT FRI JUL 31 2015

TODAY/TONIGHT...MARGINAL FOR SMALL CRAFT CONDITIONS TODAY...WITH
HIGHER WIND GUSTS POSSIBLE FOR NEARSHORE ZONES IMPACTED BY AN
OFFSHORE WIND COMPONENT IN WEST-NORTHWEST WINDS.

OUTLOOK...LIGHTER WINDS ON TAP FOR SATURDAY WITH ADDITIONAL HAZARDS
NOT EXPECTED THROUGH SATURDAY NIGHT.


&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...NONE.
LM...NONE.
LS...NONE.
&&

$$

UPDATE...SMD
NEAR TERM...JPB
SHORT TERM...JSL
LONG TERM...JSL
MARINE...JPB



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