Area Forecast Discussion
Issued by NWS Gaylord, MI

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000
FXUS63 KAPX 261441
AFDAPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
1041 AM EDT TUE MAY 26 2015

.UPDATE...
ISSUED AT 1028 AM EDT TUE MAY 26 2015

STILL LOTS OF UNCERTAINTY OVER CONVECTIVE TIMING/STRENGTH TODAY
WITH MIXED SIGNALS IN THIS REGARD. WIND FIELDS ALOFT ARE
ROBUST...WITH 0-6KM BULK SHEAR OF 40 TO 50 KNOTS. HOWEVER...LOTS
OF LOW CLOUDS ACROSS SOUTHERN LOWER MICHIGAN STREAMING NORTHWARD
(BUT THE NORTHERN EDGE IS ERODING/MIXING OUT). CURRENT AIRMASS IS
RATHER STEAMY WITH PRECIPITABLE WATERS SHOWN TO INCREASE FROM
AROUND AN INCH (12Z APX SOUNDING 1.05 INCHES) TO BETWEEN 1.5 AND
1.75 INCHES TONIGHT (NICE THETA-E RIDGE BUILDING IN). SO THERE
IS PLENTY OF MOISTURE FOR SHOWERS BUT THE QUESTION IS WHETHER OR
NOT WE CAN GET INTO ANY STRONG OR SEVERE STORMS. MODELS HAVE
BETWEEN 1000-1500 J/KG OF MIXED LAYER CAPE...WHICH WILL BE
PREDICATED ON THE AMOUNT OF DAYTIME HEATING. AT THIS POINT LIKELY
POPS LOOK GOOD AFTER 18Z BUT WILL HAVE TO WAIT AND SEE ABOUT
ANYTHING SEVERE (DAMAGING WIND THREAT). GUT FEELING IS FOR AN AREA
OF SHOWERS WITH EMBEDDED THUNDER LATER THIS AFTERNOON INTO TONIGHT
OUT AHEAD OF AN INCOMING COLD FRONT. WILL CONTINUE TO MONITOR FOR
DEVELOPMENT. MEANWHILE...LOWERED CHANCES FOR SHOWERS THROUGH 18Z
AS NOT EXPECTING MUCH IF ANYTHING TO GO ON BEFORE THEN.

&&

.NEAR TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 323 AM EDT TUE MAY 26 2015

...MORE INSTABILITY FOR THUNDERSTORMS (SEVERE?)...

SYNOPTIC PATTERN AND OBSERVATIONS:

EARLY THIS MORNING...SW FLOW ALOFT WITH SHORTWAVE TROUGHING OVER THE
CENTRAL PLAINS. WEAK VORTICITY IS CURRENTLY LIFTING INTO THE WESTERN
GREAT LAKES...ALIGNED WITH SLIGHTLY STEEPENING MID LEVEL LAPSE RATES
IN DEEPER MOISTURE/PWAT REGIME...AHEAD OF SFC TROUGHING TO OUR NORTH
AND WEST. A RELATIVE MAX IN WAA IS SEEN ACROSS NRN LAKE MICHIGAN AND
NW LOWER/EASTERN UPPER ALONG AND LEFT OF A LLJ. THIS IS WHERE THERE
HAS BEEN A BETTER COVERAGE OF SHOWERS. WHILE INSTABILITY ISN`T ALL
THAT GREAT...500 J/KG MUCAPE IS SEEN ACROSS WISCONSIN. THIS IS
DESPITE SHALLOW MID LEVEL RIDGING...AND ISOLATED SHOWERS CONTINUE TO
FIRE. A BETTER COVERAGE OF SHOWERS AND STORMS WAS NOT SURPRISINGLY
SEEN CLOSER TO THE PARENT UPPER TROUGH AND DECENT POCKET OF UPPER
DIVERGENCE NEAR DOUBLE UPPER JET STRUCTURE.

SYNOPTIC PATTERN EVOLUTION AND ASSOCIATED WEATHER:

A DEPARTING/NE LIFTING LLJ...ARRIVAL OF SHALLOW RIDGING TOWARD
DAYBREAK...AND SLOWLY DYING OFF INSTABILITY WILL LIKELY RESULT IN A
DOWNWARD TREND/LESS COVERAGE OF SHOWERS. THIS SUPPORTED BY WARMING
CLOUD TOP TREND OVER THE LAST SEVERAL HOURS. CAN FORESEE SOME
ISOLATED SHOWERS INTO THE DAYLIGHT HOURS ACROSS THE AFOREMENTIONED
FORCING IN EASTERN UPPER/NRN LAKE MI/NW LOWER...BUT AN INCREASE IN
ACTIVITY LATER THIS AFTERNOON AS THE SHORTWAVE TROUGH AND DYNAMICAL
FORCING BECOME MUCH MORE PRONE TO SPARKING A GOOD COVERAGE OF
SHOWERS. WHILE THE GREATEST FORCING WILL BE JUST WEST...THE UPPER
DIVERGENCE IN THE DOUBLE JET STRUCTURE INCREASES...ALONG WITH DPVA
AND REVAMPED LLJ CONVERGENCE AND AXIS OF HIGHER PWATS AHEAD OF SFC
LOW PRESSURE LIFTING INTO NE WI. ACROSS NRN LOWER...THINGS LOOK TO
BE MORE DIURNALLY FORCED IN CONJUNCTION WITH THE LLJ. THIS
CONVECTION WILL UNDOUBTEDLY CONTINUE THROUGH THE NIGHT AS THE SFC
LOW AND ASSOCIATED COLD FRONT CROSS INTO THE REGION. COVERAGE
UNDERGOING IT`S TYPICAL NOCTURNAL DIMINISHMENT AS THE STRONGEST
OVERALL DEEP LAYER -DIVQ DEPARTS AND INSTABILITY DWINDLES.

AS FAR AS SEVERE CHANCES GO...WE DO ACTUALLY LOOK IMPRESSIVE FOR NRN
MICHIGAN DURING PEAK HEATING/INSTABILITY FOR LATE THIS AFTERNOON AND
INTO THE EVENING AS BACKED FLOW AND A WARM FRONT LIFT THROUGH. AFTER
MODIFICATION OF SOUNDINGS...THE POTENTIAL FOR 1500-2500 J/KG OF
MLCAPE IS THERE WITH INCREASED HELICITIES TO 200 M2/S2 AND 0-6KM
BULK SHEAR OF 30-40KTS WITH A 40-50KT 500MB SPEED MAX. COULD BE A
SNEAKY SEVERE SCENARIO FOR US. WIND AND HAIL THE MAIN PLAYERS (MAX
CAPE WITHIN THE 0 TO -20C RANGE)...BUT BACKED LOW LEVEL FLOW/WARM
FRONT...CAN`T RULE OUT A TORNADO. COORDINATION WITH THE STORM
PREDICTION CENTER LEADING TO A SLIGHT RISK ACROSS NRN MICHIGAN.

&&

.SHORT TERM...(WEDNESDAY THROUGH THURSDAY NIGHT)
ISSUED AT 323 AM EDT TUE MAY 26 2015

HIGH IMPACT WEATHER POTENTIAL: NOTHING MUCH. PERHAPS A ROGUE RUMBLE
ON WEDNESDAY BUT THAT`S ABOUT IT.

A FAIRLY BASIC UPPER AIR REGIME GOING FORWARD INTO MIDWEEK AS THE
OVERALL PATTERN FLATTENS OUT ACROSS THE LOWER 48...AND HIGH PRESSURE
MAKES AT LEAST A BRIEF RUN TOWARD THE AREA. PER RECENT GUIDANCE AND
CURRENT WATER VAPOR IMAGERY TRENDS...WE WILL HAVE ONE SHORTWAVE
TROUGH AXIS TO CONTEND WITH AS IT LIFTS OUT OF THE CENTRAL PLAINS
AND TOWARD THE NORTHERN LAKES ON WEDNESDAY. THAT FEATURE WILL
PRESENT US WITH RESIDUAL CHANCES FOR SOME SHOWERS BEFORE FLATTER MID
LEVEL RIDGING ROLLS IN OVERHEAD WEDNESDAY NIGHT INTO THURSDAY...
COINCIDENT WITH THE ARRIVAL OF LOW LEVEL RIDGING EXTENDING INTO THE
REGION FROM JAMES BAY.

BY FAR THE BIGGEST FORECAST CHALLENGE WILL BE PRECIP COVERAGE ON
WEDNESDAY...WITH INCREASING HINTS OF A PERIOD OF BETTER FGEN/
DEFORMATION DRIVEN RAINS WRAPPING INTO WESTERN PORTIONS OF CHIPPEWA
AND MACKINAC COUNTIES FOR A TIME DURING THE MORNING. THE BETTER
COVERAGE OF THAT ACTIVITY...HOWEVER...LOOKS LIKE IT MAY SCRAPE BY
JUST TO THE WEST OF OUR CWA. MEANWHILE...PRONOUNCED MID LEVEL DRY
SLOTTING WILL BE FULLY IN PLACE ACROSS NORTHERN LOWER THROUGH
MIDDAY...THOUGH WITH THE POSSIBILITY FOR A LITTLE LIGHT RAIN OR SOME
SHOWERS TO SPREAD BACK INTO NORTHWEST LOWER WITH A BRIEF UPTICK IN
DEEPER MOISTURE RIGHT ALONG AND BEHIND A SURFACE TROUGH AXIS
SWINGING THROUGH. SOME ADDITIONAL ACTIVITY MAY GET SPUN UP ACROSS
WISCONSIN AND THE ARROWHEAD OF MINNESOTA INTO THE AFTERNOON BENEATH
AN AXIS OF QUITE STEEP LOW/MID LEVEL LAPSE RATES...THOUGH WITH
FAIRLY ROBUST DRYING BEHIND THE TROUGH AXIS INTO NORTHERN MICHIGAN
FOR THE AFTERNOON...NOT REALLY THINKING THIS STUFF WILL MAKE MUCH
EASTWARD PROGRESS AS THE SUN SETS.

INSTEAD...MUCH OF THE PERIOD FROM WEDNESDAY NIGHT INTO THURSDAY
NIGHT SHOULD BE RATHER QUIET AS HIGH PRESSURE RIDGES SOUTH INTO THE
AREA...WITH DEEPER MOISTURE AND HIGHER DEW POINTS INCREASINGLY
CONFINED TO OUR SOUTH THROUGH THE PERIOD. MODEST MIXING ON THURSDAY
SHOULD PROMOTE MIXING OUT OF DEW POINTS FURTHER...WITH A QUITE
COMFORTABLE DAY AS HIGHS SOAR THROUGH THE 70S TO LOW 80S BUT DEW
POINTS END UP IN THE 50S. NO CHANCE FOR ANY DIURNAL CONVECTION WITH
NOTABLE CAPPING ALOFT...THOUGH A TOUCH OF CU CERTAINLY POSSIBLE
WHERE LAKE BREEZE HELPED CONVERGENCE WILL BE STRONGEST.

&&

.LONG TERM...(FRIDAY THROUGH MONDAY)
ISSUED AT 323 AM EDT TUE MAY 26 2015

CERTAINLY ANOTHER PERIOD OF MORE ACTIVE WEATHER INTO LATE WEEK AND
AT LEAST THE FIRST PART OF THE WEEKEND...BUT WITH A NOTABLE TREND
TOWARD COOLER CONDITIONS AS WELL. STILL A FEW TIMING DIFFERENCES TO
WORK OUT AMONG GUIDANCE...BUT THE BASIC GIST IS FOR THE APPROACH OF
A STRONGER UPPER TROUGH AXIS TOWARD FRIDAY...GRADUALLY HELPING OOZE
A RATHER ROBUST FRONTAL BOUNDARY SOUTHWARD INTO THE REGION. THAT
FEATURE WILL BE DROPPING HEADLONG INTO RATHER PARALLEL FLOW
ALOFT...SUGGESTING ITS SOUTHWARD PROGRESS WILL BE SLOW AND LIKELY
DRIVEN LOCALLY BY ANY CONVECTION ALONG IT. SPEAKING OF SUCH
THINGS...MOISTURE LOOKS TO RAMP BACK UP AHEAD OF THE FRONT...WITH
INCREASING CHANCES FOR SHOWERS AND THUNDERSTORMS AREAWIDE BY FRIDAY
AND FRIDAY NIGHT. STILL QUITE A FEW QUESTIONS ABOUT JUST HOW FAST
RAIN CHANCES WILL DECLINE ON SATURDAY...BUT HAVE TO BELIEVE SLOWER
IS BETTER GIVEN THE SETUP...ESPECIALLY WITH QUITE THE AXIS OF
FRONTOGENESIS LIKELY TO SET UP NEARBY GIVEN ANOTHER INFLUX OF RATHER
CHILLY AIR JUST TO OUR NORTH. AS SUCH...IT`S NOT IMPOSSIBLE WE COULD
DEAL WITH SEVERAL ROUNDS OF RAIN ACROSS AT LEAST A PORTION OF THE
AREA RIGHT ON THROUGH THE WEEKEND...WITH TEMPS HIGHLY DEPENDENT ON
CLOUD COVER AND PRECIP COVERAGE. ALL OF THAT ASIDE...THE OVERALL
TREND WILL BE FOR MUCH COOLER READINGS...WITH THE POSSIBILITY SOME
SPOTS COULD BE QUITE CHILLY FOR A WHILE IF RAIN ENDS UP MORE
WIDESPREAD FOR LONGER.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 656 AM EDT TUE MAY 26 2015

...STORMS FOR THE AFTERNOON AND EVENING...

AS FIGURED...BAND OF SHOWERS FLOATING IN AND OUT OF PLN HAVE
DWINDLED. WE START OUT WARM WITH DECENT SFC MOISTURE. FEELING IS
THAT SCATTERED SHOWERS MAY BE ABLE TO DEVELOP RATHER
QUICKLY...MAYBE EVEN BY LATE MORNING. HOWEVER...FORCING AND
STRONGER INSTABILITY STILL PINNED FOR THIS AFTERNOON AND
EVENING...MAINLY 2 PM AND 10PM. THIS IS WHEN SFC LOW PRESSURE AND
A WARM FRONT SETTLE INTO THE REGION WITH SCATTERED THUNDERSTORMS
DEVELOPING.

INGREDIENTS AND FORCING ARE ALL THERE...AND ANTICIPATION IS THAT
ALL AIRPORTS WILL SEE SOME SORT OF RAINFALL TODAY. THERE IS A
CHANCE THAT THE INGREDIENTS ARE ENOUGH TO SUPPORT A FEW SEVERE
STORMS AS WELL. HAIL AND DAMAGING WINDS ARE THE MAIN THREAT...BUT
AN ISOLATED TORNADO CANNOT BE RULED OUT.

A COLD FRONT APPROACHES LATE TONIGHT NEAR PLN...AND ACROSS THE
REGION WEDNESDAY FOR THE REMAINDER OF THE AIRPORTS. MORE SHOWERS
AND STORMS ON TAP.


&&

.MARINE...
ISSUED AT 323 AM EDT TUE MAY 26 2015

AN AREA OF LOW PRESSURE AND WARM FRONT WILL LIFT UP THROUGH THE
GREAT LAKES TODAY AND INTO THIS EVENING. A SYSTEM COLD FRONT WILL
FOLLOW LATE TONIGHT INTO WEDNESDAY. WINDS WILL REMAIN OUT OF THE SW
BUT NOT AS GUSTY AS IT GOT AT TIMES YESTERDAY. SMALL CRAFT
ADVISORIES WILL REMAIN IN EFFECT FOR THE COASTAL CONVERGENCE REGIONS
OF NW LOWER MICHIGAN. FURTHER ADVISORY NEEDS MAY BE NEEDED LATE
TONIGHT AND INTO WEDNESDAY MORNING AHEAD AND JUST BEHIND THE COLD
FRONT.

SCATTERED SHOWERS WILL CONTINUE ACROSS NRN LAKE MI/STRAITS REGION
THIS MORNING...WHILE A MUCH GREATER COVERAGE OF SHOWERS AND
THUNDERSTORMS DEVELOPS THIS AFTERNOON AND EVENING. A FEW SEVERE
STORMS WILL BE POSSIBLE...WITH ERRATIC AND GUSTY WINDS. THE STABLE
CONDITIONS OVER THE COLDER WATERS WILL HELP HOWEVER.

CALMER CONDITIONS EXPECTED WEDNESDAY NIGHT AND INTO THURSDAY.


&&

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

$$

UPDATE...SULLIVAN
NEAR TERM...SMD
SHORT TERM...LAWRENCE
LONG TERM...LAWRENCE
AVIATION...SMD
MARINE...SMD



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