Area Forecast Discussion
Issued by NWS Gaylord, MI

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000
FXUS63 KAPX 251357
AFDAPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
957 AM EDT FRI JUL 25 2014

.SYNOPSIS...
ISSUED AT 303 AM EDT FRI JUL 25 2014

HIGH PRESSURE WILL GIVE WAY TO A FAST MOVING SYSTEM TONIGHT AND
SATURDAY. CLOUDS WILL BE ON THE INCREASE TODAY...WITH A CHANCE FOR
SHOWERS AND A FEW THUNDERSTORMS TONIGHT INTO THE START OF THE
WEEKEND. A MUCH STRONGER SYSTEM WILL ARRIVE TO END THE WEEKEND...
BRINGING BETTER POTENTIAL FOR SHOWERS SUNDAY AND SUNDAY NIGHT. A
RETURN TO MUCH BELOW NORMAL TEMPERATURES ON MONDAY...WITH ONLY A
SLOW MODERATION EXPECTED THROUGH THE REMAINDER OF THE WEEK.

&&

.UPDATE...
ISSUED AT 948 AM EDT FRI JUL 25 2014

RAIN SHOWERS OVER WISCONSIN ARE TRYING TO MAKE THEIR WAY INTO N
LOWER FOR THE AFTERNOON. WILL BE WATCHING THESE AS THEY SEEMED TO
BE HIGH BASED SHOWERS (9000-10000FT BASES) WITH SCT DECKS DOWN
LOWER. KAPX 12Z SOUNDING SHOWED LOTS OF DRY AIR, BUT ACROSS THE
LAKE KGRB 12Z SOUNDING SHOWED SOME MOISTENING BETWEEN 925 MB AND
750 MB. HOWEVER, BOTH SOUNDINGS SHOWED PRONOUNCED CAPPING
INVERSION AROUND 750 MB. SO WE ARE IN A WAIT AND SEE GAME, GUT
FEELING IS THAT WE SEE SOME SPRINKLES IN THE AFTERNOON, BUT NO
MEASURABLE RAIN SHOWERS. MAY HAVE TO BUMP THE POPS UP TO ISOLATED
SHOWERS IN NW LOWER DEPENDING ON THE TRENDS.

&&

.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 303 AM EDT FRI JUL 25 2014

...MORE CLOUDS AND A SHADE WARMER WITH STORM CHANCES TONIGHT...

IMPACTS: LIGHTNING...BUT NO SEVERE WEATHER EXPECTED.

CURRENT WEATHER AND SYNOPTIC PATTERN:

BROAD UPPER RIDGING SEEN OVER THE SW PART OF THE COUNTRY WHILE
TROUGHING IS STILL THE THEME OVER THE EASTERN CONUS. THE RIDGING HAS
BEEN SQUASHED DUE TO A WRAPPED UP CLOSED LOW DRIFTS ACROSS SW
CANADA. THIS HAS INDUCED LOW PRESSURE OVER EASTERN CANADA AND THE
NRN PLAINS. AN AXIS OF DEEP THETA-E AIR...LEADING EDGE OF STEEP
LAPSE RATES ALOFT (6.5C/KM-7.5C/KM) AND LLJ (45-55KT) CONVERGENCE
AHEAD OF THE PLAINS SFC LOW HAS RESULTED IN POCKETS OF SHOWERS AND
STORMS IN THE DAKOTAS DOWN TO NE. CLOSER TO HOME...AREA VAD WIND
PROFILES AND RUC ANALYSIS SHOWING A TROUGH AXIS AND H8 MOISTURE
ADVECTION FROM THE ARROWHEAD OF MN DOWN THROUGH WISCONSIN. THERE
WERE A FEW ELEVATED RETURNS...BUT ONLY A FEW SPRINKLES HITTING
GROUND PER AREA OBS. OVER NRN MICHIGAN...WE ARE STILL UNDER THE
INFLUENCE OF SFC HIGH PRESSURE...BUT THOSE SAME VAD WIND PROFILES
SHOW THAT THIS HAS SHIFTED JUST EAST OF US WITH A RETURN TO A SW
WIND. AIR MASS IS STILL QUITE DRY WITH PWATS RELATIVELY LOWER THAN
ANYWHERE NEARBY. ONLY A BAND OF HIGHER LEVEL CLOUD STREAMING DOWN
THROUGH THE NW FLOW ALOFT. THE DRY AIR AND MOSTLY CLEAR SKIES HAVE
ALLOWED TEMPERATURES TO FALL INTO THE LOWER HALF OF THE 40S IN THE
LOW LYING AREAS...WHILE COASTAL AREAS AND SOME EXPOSED HIGHER
TERRAIN ARE IN THE LOWER HALF OF THE 50S.

SYNOPTIC PATTERN/WEATHER EVOLUTION:

THE SFC HIGH GRADUALLY SINKS OFF TO THE SE TODAY...WHILE THE
SOUTHERLY PRESSURE GRADIENT TIGHTENS AND DRAWS IN MORE LOW LEVEL
MOISTURE THROUGH THE DAY AND NIGHT. THE INITIAL H8 TROUGH AND
MOISTURE ADVECTION WILL DRIFT OVERHEAD TODAY...AND MAYBE SOME
SPRINKLES ARE POSSIBLE EARLY THIS MORNING...BUT DAYTIME MIXING AND
DRYING OF THE LOWER LEVELS WILL MOST LIKELY SEAL OFF ANY CHANCES FOR
SPRINKLES TO HIT GROUND. THE MOISTURE WILL REVEAL ITSELF IN A HIGHER
BASED CUMULUS FIELD...BUT ALSO MAY GET STUCK UNDERNEATH AN INVERSION
IN FCST BFR SOUNDINGS. THIS COULD LEAD TO A PERIOD OF MOSTLY CLOUDY
SKIES...BUT REALLY DOUBT THIS WILL HAVE MUCH AFFECT ON RISING TEMPS
REACHING THE MIDDLE 70S MOST AREAS. THIS INVERSION AND DRY SFC TDS
RESULT IN A PRETTY PRONOUNCED CAPPING FOR THE ENTIRE DAY...WITH
LITTLE TO NO CHANCE FOR AFTERNOON CONVECTION.

THERE ARE DIFFERENCES IN HOW THIS LID EVOLVES OVER THE NIGHT...BUT
WE WILL AT LEAST BE TRENDING TOWARD MORE UNSTABLE CONDITIONS. SOME
SHORTWAVE ENERGY/VORTICITY EJECTS FROM AFOREMENTIONED CLOSED LOW
DRIFTING THROUGH SRN CANADA. THIS FORCING ARRIVES LATE EVENING AND
OVERNIGHT. WEAK LOW PRESSURE AND A WARM FRONT LIFT UP TOWARD/INTO
NRN MICHIGAN. THE SAME FCST BFR SOUNDINGS...IN A SCENARIO LIKE
THIS...WOULD LIKELY ERODE/SUPPRESS THE CAP...UNLIKE THE GFS
SUGGESTION. RATHER...WILL GO WITH SHOWERS AND EMBEDDED
GARDEN-VARIETY THUNDERSTORMS DEVELOPING LATE EVENING/OVERNIGHT.
NOTHING SEVERE ANTICIPATED...AS OUR LAPSE RATES AND OVERALL
INSTABILITY WILL NOT MIRROR CURRENT ENVIRONMENT ACROSS THE NRN
PLAINS. WE WILL ONLY HAVE SEVERAL HUNDRED J/KG MUCAPE WITH LAPSE
RATES ALOFT 6-6.5C/KM. THE GREATEST MUCAPE LIKELY TO BE DOWN AROUND
THE MANISTEE/CADILLAC AREAS...ALSO WHERE SOME ADDITIONAL LIFT
ASSISTANCE WILL BE PROVIDED BY UPPER DIVERGENCE IN SOMEWHAT OF A
DOUBLE JET STRUCTURE. WOULD GO WITH LIKELY CHANCES FOR SEEING
PRECIPITATION...BUT BULK OF INSTABILITY AND LLJ FORCING WILL ONCE
AGAIN BE ACROSS SRN WI/NRN IL/SRN LAKE MICHIGAN. THIS COULD BLOCK US
FROM SEEING SOME OF THE ACTION. REGARDLESS...LIKELY TO BE SOME
PRECIPITATION...BEST DESCRIPTION OF WHICH CAN BE PROVIDED BY LATER
SHIFTS AS THE EVENT UNFOLDS.

LOWS TONIGHT WILL LIKELY BE MILD WITH THICKENING CLOUDS...LOWER HALF
OF THE 60S MOST AREAS.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 303 AM EDT FRI JUL 25 2014

...RAINY END TO THE WEEKEND/COOL TEMPERATURES ON THE WAY FOR THE
START OF NEXT WEEK...

HIGH IMPACT WEATHER POTENTIAL: NOT A BUNCH. CHANCES FOR A FEW
NON-SEVERE THUNDERSTORMS HEADING THROUGH THE WEEKEND.

PATTERN SYNOPSIS/ANTICIPATED EVOLUTION: WHILE STILL PLENTY OF THE
FINER DETAILS TO WORK OUT...MUCH TALKED ABOUT TRANSITION TO A MORE
MERIDIONAL NOAM UPPER FLOW PATTERN STILL ON TARGET TO DEVELOP HEADING
INTO AND THROUGH NEXT WEEK. NO LINGERING DOUBT MICHIGAN WILL BE
CENTERED IN UNSEASONABLY CHILL PRODUCING TROUGH AXIS...WHICH WILL BE
A SLOW ONE TO DEPART ONCE IT DEVELOPS. PLAYERS FOR SUCH UNUSUAL
DEVELOPMENTS ALREADY ON THE TABLE...WITH LARGE NORTHERN QUEBEC GYRE
SIMPLY STUCK IN PLACE...ALL THE WHILE STRONG PACIFIC SHORTWAVE MAKES
STEADY EAST PROGRESS ACROSS THE SOUTHERN CANADIAN ROCKIES. THE
LATTER WILL SIMPLY REINFORCE AND EXTEND THE FORMER AS IT
SLING-SHOTS AROUND IT THROUGH EARLY NEXT WEEK. COMBINE THAT WITH
DEVELOPMENT OF FULLY MATURE GULF OF ALASKA TROUGH/WEST NOAM RIDGE
COUPLET (NOT TO MENTION ONE REALLY AMPLIFIED ATLANTIC RIDGE)...AND
ONE CAN SEE WHY A PATTERN MUCH MORE RESEMBLING THE COOL SEASON IS
EXPECTED.

PRIMARY FORECAST CONCERNS/CHALLENGES: TEMPERATURE TRENDS THROUGHOUT
AND EVOLUTION OF PERIODIC RAIN CHANCES. THUNDERSTORM POTENTIAL AND
INTENSITY WILL ALSO NEED ADDRESSING THIS WEEKEND.

DETAILS: SATURDAY CONTINUES TO REMAIN A CHALLENGE...WITH TIGHT
THETA-E GRADIENT AND SURGE OF BEST UPPER JET FORCING EXITING STAGE
RIGHT RATHER QUICKLY DURING THE MORNING. LEFT BEHIND WILL BE A MUCH
MORE MOIST LOW LEVEL AIRMASS...WITH DEWPOINTS EXPECTED TO BE UP IN
THE MID AND PERHAPS UPPER 60S. KINDA EXPECT WHAT EVER PUNCHES
THROUGH HERE TONIGHT WILL LARGELY EXIT DURING THE MORNING
HOURS...LEAVING NEXT LOW AMP WAVE AND DIURNAL DRIVEN DESTABILIZATION
TO DRIVE ADDITIONAL SHOWER AND STORM DEVELOPMENT. MOISTURE CROSS
SECTIONS SHOW GOOD TO EXCELLENT MOISTURE DEPTH UP THROUGH H7...WITH
AGGRESSIVE DRYING ABOVE THIS LAYER. MANIPULATING MODEL DERIVED
SOUNDINGS WITH ANTICIPATED DEWPOINTS/TEMPERATURES DOES YIELD
DEVELOPMENT OF UPWARDS OF 1K-1.5K J/KG OF ML CAPE DURING THE
AFTERNOON. THINK THIS MIGHT BE A TOUCH AGGRESSIVE...EXPECTING LOW
LEVELS TO BE NOT QUITE AS SATURATED AS GUIDANCE WOULD SUGGEST. WHILE
BEST DYNAMICS WILL HAVE EXITED...NOT ALL IS LOST...WITH MID LEVEL
JET ROTATING THROUGH THE SOUTHWEST LAKES...COMBINING WITH LAKE
INDUCED LOW LEVEL CONVERGENCE /PARTICULARLY IN NORTHEAST LOWER AND
INTERIOR EASTERN UPPER MICHIGAN/ AND SAID WEAK WAVE. ABOVE
DEFINITELY SUPPORTS SOME ADDITIONAL CONVECTIVE POTENTIAL...
ESPECIALLY IN CLIMATOLOGICALLY FAVORED AREAS. INHERITED FORECAST
ALREADY WELL TRENDED IN THIS DIRECTION...WITH ONLY SOME MASSAGING
NEEDED TO POP/WEATHER GRID. DECENT DEEP LAYER SHEAR OF 30 TO 40
KNOTS LARGELY OFFSET BY LIMITED MID LEVEL LAPSE RATES AND SKINNY
CAPE PROFILE UP THROUGH HAIL GROWTH ZONE. SO...IF STORMS CAN DEVELOP
(A BIG IF)...WOULD EXPECT THEM TO REMAIN BELOW SEVERE LIMITS.

LOSS OF INSTABILITY AND RAPID APPROACH OF SHORTWAVE RIDGING EXPECTED
TO BRING A MOSTLY DRY SATURDAY NIGHT. RATHER VIGOROUS CURRENT
SOUTHERN CANADA WAVE QUICKLY FOLLOWS FOR SUNDAY...AND WHEN COMBINED
WITH GOOD SLUG OF LEFT EXIT REGION UPPER JET DYNAMICS...LOOKS TO
BRING A RATHER WIDESPREAD SHOWER EVENT SUNDAY INTO SUNDAY NIGHT.
SYSTEM EVEN LOOKS TO TAKE ON COLD SEASON CHARACTERISTICS...WITH MORE
STEADY RAIN POTENTIAL IN FAVORED NORTH SIDE DEFORMATION FIELD. SOME
THUNDER THREAT REMAINS SUNDAY WITH OPPORTUNITY FOR SOME
DESTABILIZATION BEFORE BETTER FORCING ARRIVES.

TROUGHING DIGS IN AND STAYS THERE-ON-AFTER...PERHAPS LASTING THROUGH
ALL OF NEXT WEEK. COLDEST ANOMALIES EXPECTED TO SLIDE JUST OFF TO
OUR NORTHEAST. THAT SAID...COLD AIR ADVECTION ON FRONT SIDE OF
SPRAWLING NORTHERN PLAINS HIGH WILL BE IMPRESSIVE INDEED...ONCE
AGAIN NOT ALLOWING TEMPERATURES TO GET OUT OF THE 60S ON MONDAY. A
VERY SLOW MODERATION TO FOLLOW...WITH HIGHS WARMING A FEW DEGREES
EACH DAY THROUGH THURSDAY (EVEN BY THURSDAY...HIGHS WILL STILL BE A
FEW DEGREES BELOW NORMAL). DESPITE TROUGHING...JUST NOT OVERLY
IMPRESSED WITH RAIN CHANCES AFTER SUNDAY NIGHTS WAVE PASSAGE. DEEP
LAYER FLOW WILL REMAIN NORTH TO NORTHWEST...AND MID LEVEL
TEMPERATURE REALLY NEVER GET TOO COLD...REACHING THE NEGATIVE UPPER
TEENS AT H5 LATER MONDAY INTO TUESDAY. OF COURSE...ANY WAVES
ROTATING THROUGH WILL ONLY HELP THE SHOWER CAUSE...BUT TIMING AND
MAGNITUDE OF SUCH NOT POSSIBLE TO DETERMINE JUST YET. NO REASON TO
CHANGE THAT WHICH WAS INHERITED...FEATURING JUST ISOLATED/LOW CHANCE
SHOWER POTENTIAL DURING THE DAYTIME HOURS. THIS WILL CHANGE...OF
COURSE...BUT PLENTY OF TIME TO FIGURE THOSE DETAILS OUT IN THE
COMING DAYS.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 609 AM EDT FRI JUL 25 2014

...MAINLY VFR WITH CHANCES FOR SHOWERS AND STORMS TONIGHT...

SFC HIGH PRESSURE HAS EXITED SOUTHEAST ALLOWING FOR A LIGHT SW
RETURN FLOW. THIS GRADIENT TIGHTENS A TOUCH TODAY WITH GUSTS UP TO
15-18KTS EXPECTED...MAINLY ACROSS NW LOWER. CUMULUS AND SOME
HIGHER CLOUD EXPECTED TO ROLL ON THROUGH TODAY AND POSSIBLY GET
STUCK UNDERNEATH AN INVERSION FOR A PERIOD OF MORE CLOUDY
CONDITIONS. WEAK LOW PRESSURE AND A WARM FRONT ARRIVE TONIGHT WITH
THE CHANCE FOR SHOWERS AND STORMS AHEAD OF IT. EXACT EVOLUTION OF
THE PRECIPITATION NEBULOUS RIGHT NOW...WILL INCLUDE A VCSH FOR THE
NIGHT.

NO SEVERE WEATHER ANTICIPATED. BRIEF HEAVY RAIN AND LIGHTNING
HOWEVER.


&&

.MARINE...
ISSUED AT 303 AM EDT FRI JUL 25 2014

SW WINDS WILL INCREASE HEADING THROUGH TONIGHT...AHEAD OF SFC LOW
PRESSURE AND A WARM FRONT...WHICH WILL BRING AREAS OF SHOWERS AND
GARDEN-VARIETY STORMS TO THE GREAT LAKES. NOTHING SEVERE....AND
WINDS TO REMAIN ABOVE ADVISORY LEVELS. EXPECTING NO MORE THAN
20KTS..WHICH WILL LARGELY RESIDE ACROSS LAKE MICHIGAN. WINDS REMAIN
UNDER ADVISORY LEVELS SATURDAY AND SUNDAY IN WEAK GRADIENT. ANOTHER
SFC LOW CROSSES SUNDAY MORNING WITH A BETTER CHANCE FOR SHOWERS AND
STORMS...AND MUCH COOLER AIR SET TO ARRIVE THROUGH THE DAY SUNDAY
AND SUNDAY NIGHT.


&&

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

&&

$$

UPDATE...JL
SYNOPSIS...MSB
SHORT TERM...SMD
LONG TERM...MSB
AVIATION...SMD
MARINE...SMD





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