Area Forecast Discussion
Issued by NWS Gaylord, MI

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000
FXUS63 KAPX 200127
AFDAPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
927 PM EDT TUE AUG 19 2014

.SYNOPSIS...
ISSUED AT 428 PM EDT TUE AUG 19 2014

UNSETTLED WEATHER WILL REMAIN ACROSS NORTHERN MICHIGAN INTO
WEDNESDAY...AS UPPER LEVEL LOW PRESSURE SPINS OVERHEAD. THIS SYSTEM
WILL SLOWLY DEPART WEDNESDAY NIGHT...JUST IN TIME FOR A WARM FRONT
TO SLOWLY INCH NORTH THROUGH THE GREAT LAKES FOR LATE WEEK. THAT
FEATURE WILL DELIVER ADDITIONAL CHANCES FOR SHOWERS AND
THUNDERSTORMS RIGHT ON THROUGH THE WEEKEND.

&&

.UPDATE...
ISSUED AT 927 PM EDT TUE AUG 19 2014

IT TOOK TIL ALMOST 8 PM...BUT CONVECTION FINALLY DEVELOPED
SOUTHWARD ALONG THE LEADING EDGE OF THE HIGHER TERRAIN IN NW
LOWER...ALMOST TO KALKASKA. 00Z APX SOUNDING HAD ABOUT 700J/KG OF
SKINNY SBCAPE. HOWEVER...THIS ACTIVITY SEEMS TO HAVE ALREADY
PEAKED AS THAT INSTABILITY STARTS TO WANE.

EARLIER ORGANIZED LINE OF CONVECTION UPSTREAM...ALMOST COINCIDENT
WITH THE 500MB LOW...IS ALSO SUBSTANTIALLY WEAKENING. THE UPPER
LOW WILL DRIFT ACROSS CENTRAL AND APPROACH EASTERN UPPER MI
TONIGHT. THERE IS NOT A TREMENDOUS POCKET OF COLD AIR ALOFT
ASSOCIATED WITH THE UPPER LOW...500MB TEMPS WILL ONLY LOWER 1C.
THERE IS A SHORTWAVE BACK IN WESTERN UPPER THAT WILL ROTATE AROUND
THE LOW...BRINGING A SHOT OF DPVA INTO WESTERN SECTIONS
(ESPECIALLY NW LOWER) OVERNIGHT. WITH THE LOW LEVELS REMAINING
MOIST AND THE MID LEVELS SEEING A NEAR MOIST-ADIABATIC LAPSE
RATE...THE WINDOW IS OPEN FOR SCT SHRA TO DEVELOP JUST ABOUT ANY
TIME...ANYWHERE. BUT THE MODELS ARE GENERALLY NOT ENTHUSIASTIC
ABOUT PRECIP CHANCES OVERNIGHT.

CURRENT EXPECTATIONS ARE TO LET ONGOING CONVECTION PLAY OUT OVER
THE NEXT 2-3 HOURS. THEN WE SHOULD ONLY NEED RELATIVELY SMALL
CHANCE POPS (30-40) FOR THE OVERNIGHT.

LOW STRATUS IS ALREADY EXTENSIVE FROM THE STRAITS AREA NORTH.
WON/T TAKE MUCH LOWERING TO RESULT IN FOG. MEANWHILE...PARTIAL
CLEARING NOW IN NW/N CENTRAL LOWER WILL MAKE EASTWARD PROGRESS.
THAT WILL ALSO RESULT IN FOG DEVELOPMENT IN NORTHERN LOWER.

&&

.SHORT TERM...(THIS EVENING THROUGH TONIGHT)
ISSUED AT 428 PM EDT TUE AUG 19 2014

THIS EVENING AND INTO TONIGHT...MAIN CONCERN IS VERY LOCALIZED HEAVY
RAINFALL. NEARLY STATIONARY UPPER LEVEL LOW PRESSURE SYSTEM STILL
REMAINS OVER THE GREAT LAKES REGION. MAIN AREA OF RAINFALL/STORMS
HAVE BEEN CONFINED TO SOUTHERN LOWER MICHIGAN...WITH SOME REPORTS OF
DOWNED TREES...2.50 INCHES OF RAINFALL IN LESS THAN AN HOUR...AND
SMALL HAIL. AFTER WAITING ALL DAY...BREAKS IN THE CLOUD COVER OVER
OUR NECK OF THE WOODS HAS FINALLY ALLOWED DIURNAL HEATING ALONG WITH
AN AREA OF LOW LEVEL CONVERGENCE OVER NORTHEAST LOWER AND EASTERN
UPPER TO DESTABILIZE THE ATMOSPHERE JUST ENOUGH TO FIRE OFF SOME
SHOWERS. THESE SHOWERS WILL NOT BECOME WIDESPREAD...BUT STAY RATHER
SPORADIC THROUGH SUNSET. ANY STRONGER RAIN SHOWERS AND/OR EVEN A
THUNDERSTORM THAT MAY DEVELOP...WILL PRODUCE...ALBEIT VERY
LOCALIZED...HEAVY RAINFALL. PWATS ARE STILL IN EXCESS OF 1.50 INCHES
WITH SKINNY CAPE PROFILES ON FORECAST SOUNDINGS OF 700 J/KG CAPE
WITH MINIMAL CIN. OTHERWISE...MOSTLY CLOUDY TO OVERCAST SKY COVER
AND MILD TEMPERATURES WILL PROVIDE A DESCENT NORTHERN MICHIGAN
EVENING OUTSIDE OF ANY RAIN SHOWERS/THUNDERSTORMS. ONCE THIS WAVE
PASSES THROUGH NORTHERN MICHIGAN LATER THIS EVENING...ANOTHER
WAVE...CURRENTLY OVER WESTERN UPPER/NORTHEASTERN WISCONSIN...WILL
PRODUCE ANOTHER ROUND OF HIT AND MISS LIGHT RAIN SHOWERS DURING THE
OVERNIGHT HOURS ALONG WITH ABUNDANT LOW-LEVEL MOISTURE TRAPPED BELOW
AN INVERSION THAT WILL SET UP LATE TONIGHT AND PRODUCE WIDESPREAD
STRATUS THROUGHOUT THE FORECAST AREA ALONG WITH AREAS OF MORNING
FOG. OVERNIGHT TEMPERATURES OF THE UPPER 50S AND LOW 60S STILL LOOK
TO BE ON TRACK. SOUTHERLY WINDS WILL REMAIN FAIRLY LIGHT AND
DIMINISH EVEN MORE AFTER SUNSET.

.LONG TERM...(WEDNESDAY THROUGH TUESDAY)
ISSUED AT 428 PM EDT TUE AUG 19 2014

FOUR-WAVE LONG WAVE PATTERN IN PLACE TO START THIS FORECAST CYCLE
WITH ONE LONG WAVE TROUGH THROUGH THE CENTRAL CONUS AND BROAD
RIDGING IN THE EASTERN PACIFIC AND WESTERN ATLANTIC. PATTERN IS NOT
EXPECTED TO CHANGE MUCH OVER THE COURSE OF THE NEXT SEVEN DAYS...
ALTHOUGH TROUGHINESS ACROSS THE CONUS IS STILL FORECAST TO
RETROGRADE WESTWARD INTO THE ROCKIES LATE THIS WEEK AND INTO THE
WEEKEND AS RIDGING/WARM AIR BUILDS OVER THE GULF COAST AND SE STATES
UP INTO THE GREAT LAKES. STILL LOOKING LIKE A PERIOD OF RELATIVE
WARMTH THROUGH THE WEEKEND ALTHOUGH TEMPS MAY BE TEMPERED BY PRECIP
CHANCES ALONG THE NRN FRINGE OF THE RIDGE/WARM AIR. COLD FROPA AND
UPPER HEIGHTS BREAK DOWN EARLY NEXT WEEK KNOCKING OUR TEMPS BACK
DOWN.

WEDNESDAY/WEDNESDAY NIGHT...PSEUDO CUTOFF LOW SPINNING INTO
THE WESTERN GREAT LAKES TODAY WILL TAKE THE NEXT DAY OR TWO TO WORK
THROUGH THE REGION...PRESENTING VARYING PRECIP CHANCES. CLOSED UPPER
LOW AMD WEAK QG-FORCING REGIME SETTLES OVER THE STATE FOR WEDNESDAY.
AND WITH COOL-ISH AIR ALOFT...FORECAST SOUNDINGS REVEAL SOME MODEST
SKINNY +CAPE THROUGH THE AFTERNOON HOURS AND SUGGESTS CONVECTION
WILL BECOME MORE PREDOMINANT DURING THE AFTERNOON HOURS AND
PARTICULARLY OVER NE LOWER MICHIGAN WHERE INSTABILITY/CONVERGENCE
WILL BE GREATEST.

HEAVY RAIN THREAT...CERTAINLY A MOIST AIRMASS WILL REMAIN IN PLACE
THROUGH WEDNESDAY WITH PWAT VALUES UP AROUND 1.5 INCHES. IF WE GET
CONVECTION TO DEVELOP...WEAK/VARIABLE WIND FIELDS AROUND THE STACKED
LOW PRESSURE SYSTEM COULD LEAD TO SLOW MOVING HEAVY RAIN PRODUCING
SHOWERS/STORMS WEDNESDAY AFTERNOON INTO THE EVENING. WILL CONTINUE
TO MENTION HEAVY RAIN POTENTIAL IN THE HAZARDOUS WEATHER OUTLOOK
THROUGH WEDNESDAY NIGHT.

BY THURSDAY...UPPER LOW FILLS AND SLIPS OFF THROUGH NEW YORK STATE
DURING THE DAY WHILE UPPER RIDGING AND WARMER AIR AGAIN STARTS TO
NOSE INTO THE GREAT LAKES FROM THE SW. ISOLATED HEATING INDUCED
SHOWERS AGAIN NOT OUT OF THE QUESTION THURSDAY AFTERNOON ALTHOUGH
CHANCES LOOK MUCH LOWER AS UPPER LEVELS WARM AND WE DEVELOP SOME
CAPPING. BUT MEANWHILE...NARROW AXIS OF WARM FRONTAL PRECIP DEVELOPS
ACROSS THE FAR WESTERN GREAT LAKES INTO THE MIDWEST ALONG A RENEWED
PUSH OF WARM/MOIST AIR INTO THE REGION WITH SOME OF THAT ACTIVITY
POSSIBLY SKIRTING INTO THE SW PART OF THE CWA BY LATE AFTERNOON AND
THURSDAY NIGHT.

FRIDAY THROUGH SUNDAY...UPPER LEVEL HEIGHTS BUILD THROUGH THE
WEEKEND WITH H5 HEIGHTS PUSHING 588 DM ACROSS SRN LOWER MICHIGAN...
SUGGESTING THE POTENTIAL FOR A WARM STRETCH OF WEATHER ACROSS THE
GREAT LAKES. HOWEVER...PRECIP CHANCES REMAIN THE EXTENDED FORECAST
PROBLEM OF THE DAY. EURO/GFS BOTH SUGGEST SOME CONFIGURATION OF A
SFC LOW LIFTING INTO THE UPPER MIDWEST WITH ATTENDING WARM FRONT
EDGING ITS WAY NORTHWARD INTO OR THROUGH THE STATE...ALTHOUGH JUST
HOW FAR NORTH THESE FEATURES ACTUALLY GET IS STILL HIGHLY UNCERTAIN.
REGARDLESS...WITH ANOTHER COUPLE OF SURGES OF WARM/MOIST (HIGH
THETA-E) AIR INTO NRN MICHIGAN...UNFORTUNATELY FOR NOW WE HAVE TO
KEEP SHOWER/STORM CHANCES GOING FRIDAY AND THROUGH MUCH OF THE
UPCOMING WEEKEND. BUT HOPEFULLY WE CAN BETTER REFINE THOSE CHANCES
AS WE GET CLOSER TO THE WEEKEND. OTHERWISE...POTENTIAL IS THERE FOR
SOME REALLY WARM TEMPS FRIDAY THROUGH SUNDAY PROVIDED CLOUDS/PRECIP
DON/T MESS THINGS UP. CURRENTLY HAVE HIGHS IN THE MID 70S TO LOWER
80S BUT WARMER READINGS ARE POSSIBLE.

MONDAY AND TUESDAY (LATER PERIODS)...STRONG PIECE OF SHORT WAVE
ENERGY EXPECTED TO EJECT OUT OF THE ROCKIES AND INTO THE NRN GREAT
LAKES/ONTARIO REGION BY TUESDAY...DRIVING A COLD FRONT DOWN INTO THE
GREAT LAKES DURING THIS TIME...ALTHOUGH TIMING AGAIN REMAINS
PROBLEMATIC. WILL TRY TO SQUEEZE OUT A DRY FORECAST FOR MONDAY (TO
BREAK UP THE MONOTONY) BUT BRING PRECIP CHANCES BACK IN FOR TUESDAY
AS THE FRONT SWINGS THROUGH.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 754 PM EDT TUE AUG 19 2014

CONDITIONS DETERIORATING TO IFR TONIGHT...SLOWLY IMPROVING TO MVFR
WEDNESDAY.

LOW PRESSURE WILL WEAKEN AS IT DRIFTS EAST FROM NORTHERN LAKE MI
TO EASTERN LOWER MI DURING THE TAF PERIOD. THE WX WILL REMAIN
UNSETTLED...WITH PERIODIC CHANCES FOR SHRA AND PERHAPS A TSRA. THE
MAIN STORY FOR TONIGHT IS AN INTRUSION OF DRY AIR ALOFT...ALLOWING
FOR A PERIOD OF PARTIAL CLEARING. THE LOW LEVELS REMAIN
MOIST...AND FOG/STATUS IS STILL EXPECTED LATE TONIGHT. A LENGTHY
PERIOD OF IFR CONDITIONS IS FORECAST AT ALL TAF SITES.

LIGHT WINDS THRU THE FORECAST.


&&

.MARINE...
ISSUED AT 439 PM EDT TUE AUG 19 2014

CANCELLED THE SMALL CRAFT ADVISORY DUE TO THE WINDS NEVER REACHING
CRITERIA AS ANTICIPATED. AS AN UPPER LEVEL LOW PRESSURE SYSTEM SPINS
NEARLY STATIONARY OVER THE GREAT LAKES...PRESSURE GRADIENTS SHOULD
REMAIN FAIRLY RELAXED AND WINDS/WAVES UNDER SMALL CRAFT CRITERIA.
HEAVY RAINFALL IS POSSIBLE OVER THE NEARSHORE WATERS OF LAKE HURON
AND THE SAINT MARY/S RIVER SYSTEM AS SHOWERS AND POSSIBLY EVEN A
THUNDERSTORM MAY STILL DEVELOP DURING THE REST OF THE AFTERNOON AND
INTO THE EVENING HOURS. FOG IS ALSO A POSSIBILITY DURING THE
OVERNIGHT HOURS AND INTO THE EARLY MORNING HOURS WEDNESDAY. SHOWERS
AND STORMS ARE POSSIBLE ONCE AGAIN WEDNESDAY AFTERNOON OVER ALL OF
THE NEARSHORE WATERS OF NORTHERN LOWER AND EASTERN UPPER
MICHIGAN...WITH HEAVY RAINFALL BEING THE MAIN CONCERN ONCE AGAIN.
THE UPPER LEVEL LOW PRESSURE DEPARTS EAST BY THURSDAY AND HIGH
PRESSURE BUILDS INTO THE FORECAST AREA...PRODUCING PRECIPITATION-
FREE WEATHER.


&&

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

&&

$$

UPDATE...JZ
SYNOPSIS...KB
SHORT TERM...TL
LONG TERM...ADAM
AVIATION...JZ
MARINE...TL





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