Area Forecast Discussion
Issued by NWS Gaylord, MI

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000
FXUS63 KAPX 212300
AFDAPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
700 PM EDT THU AUG 21 2014

.SYNOPSIS...
ISSUED AT 356 PM EDT THU AUG 21 2014

MAINLY DRY AND SEASONABLE CONDITIONS THIS AFTERNOON WILL GIVE WAY TO
A GRADUAL INCREASE IN SHOWER AND THUNDERSTORM CHANCES TONIGHT INTO FRIDAY.
ADDITIONAL SLIGHT CHANCES FOR ISOLATED SHOWERS AND THUNDERSTORMS WILL
CONTINUE OVER THE WEEKEND INTO EARLY NEXT WEEK...AS SEVERAL WEAK
SYSTEMS TRACK NEARBY.

&&

.SHORT TERM...(THIS EVENING THROUGH TONIGHT)
ISSUED AT 356 PM EDT THU AUG 21 2014

...SHOWER AND STORM CHANCES (FOR SOME)...

HIGH IMPACT WEATHER POTENTIAL: MINIMAL. TYPICAL NON-SEVERE THUNDER
CONCERNS TONIGHT (LIGHTNING AND LOCALLY HEAVY RAIN).

PATTERN SYNOPSIS/ANTICIPATED EVOLUTION: LARGER SCALE PATTERN
AMPLIFICATION CONTINUES...WITH DIGGING WESTERN TROUGHING FORCING
UPPER MISSISSIPPI VALLEY/WESTERN GREAT LAKES RIDGE AMPLIFICATION.
DOWNSTREAM QUEBEC BLOCK ONLY ADDING TO THIS AMPLIFICATION
PROCESS...WITH ABOVE WORKING IN TANDEM TO BUILD OVERHEAD HEAT DOME
THROUGH THIS WEEKEND. STRONG WARM/MOIST ADVECTION AND ATTENDANT
THERMAL/INSTABILITY GRADIENTS KICKING OFF AREAS OF SHOWERS AND
STORMS TO OUR WEST AND SOUTH...SOME OF WHICH HAVE BEEN RATHER
PROLIFIC RAINFALL PRODUCERS. MUCH QUIETER AND COOLER CLOSER TO
HOME...WITH AREA WELL REMOVED FROM QUASI-STATIONARY WARM FRONT
DRAPED OVER THE LOWER LAKES.

PRIMARY FORECAST CONCERNS/CHALLENGES: SHOWER/STORM EVOLUTION.

DETAILS: JUST ANOTHER NORTHERN MICHIGAN LOW CONFIDENCE SHOWER AND
STORM FORECAST. JUST UPSTREAM TIGHT MOISTURE/INSTABILITY GRADIENT
FORCES SUCH FORECAST UNPLEASANTRIES...AND THAT DOES NOT LOOK TO
CHANGE MUCH DURING THE OVERNIGHT. SOME SLOW EAST PROGRESSION FOR
SURE...BUT BY AND LARGE BETTER SHOWER AND STORM CHANCES LOOK TO
REMAIN OFF TO OUR WEST AND SOUTH...WITH THE LATTER AREAS ENHANCED BY
DEVELOPING AND STEADILY VEERING LOW LEVEL JET STRUCTURE. RAINS WILL
ONLY HELP TIGHTEN ALREADY WELL ESTABLISHED SOUTHWEST LAKES THERMAL
GRADIENT...WHICH IN TURN WILL ACT TO REINFORCE CURRENT LOWER LAKES
QUASI-STATIONARY FRONT. SIMPLY HAVE NO REASON NOT TO BELIEVE VAST
MAJORITY OF HIGH RESOLUTION MODEL GUIDANCE /STRONGLY SUPPORTED BY
SIMPLE PATTERN RECOGNITION/ THAT MOST OF THE HEAVIER RAIN PRODUCING
SHOWERS AND STORMS WILL PROPAGATE EAST/SOUTHEAST INTO AND THROUGH
THE LOWER LAKES. KEY FOR US FURTHER NORTH WILL BE INTERACTION OF
SUBTLE SHORTWAVE AND SUBSEQUENT UPTICK IN OFF THE DECK WAA REGIME.
BELIEVE THIS MAY PROVIDE THE SPARK TO KICK OFF SOME RAIN...
ESPECIALLY ACROSS FAR SOUTHWEST AREAS WHERE ABOVE INTERCEPTS
NORTHERN EXTENT OF POSSIBLE SOUTHWEST LAKES CONVECTIVE COMPLEX. WILL
LARGELY KEEP INHERITED FORECAST IN-TACT...TAILORING POPS RAPIDLY
FROM SOUTHWEST TO NORTHEAST...KEEPING EASTERN UPPER AND NORTHEAST
LOWER MOSTLY DRY OVERNIGHT. EXPECTING ANY SEVERE/HEAVY RAIN THREAT
TO REMAIN OUTSIDE OUR AREA.

.LONG TERM...(FRIDAY THROUGH THURSDAY)
ISSUED AT 356 PM EDT THU AUG 21 2014

...WARM AND HUMID THROUGH THE WEEKEND AND EARLY NEXT WEEK...

FOUR TO FIVE WAVE HEMISPHERIC PATTERN IN PLACE TO START THIS
FORECAST CYCLE WITH LONG WAVE TROUGHINESS ACROSS WESTERN NOAM AND
RIDGING BUILDING ACROSS THE SE STATES. SHORT WAVE RIDGING CONTINUES
TO BUILD ACROSS THE GULF COAST STATES WITH RIDGING/WARM AIR BUILDING
UP THROUGH THE MIDWEST AND FAR WESTERN GREAT LAKES...SETTING UP A
CLASSIC "RING OF FIRE" PATTERN. ONE ROUND OF DECAYING CONVECTION
ALONG/NORTH OF WARM FRONT DRAPED THROUGH THAT AREA. FURTHER
UPSTREAM...STRONG SHORT WAVE ENERGY OUT OF THE GULF OF ALASKA
DIGGING INTO THE PAC NW...THAT WILL CARVE OUT SUBSTANTIAL
TROUGHINESS ACROSS THE WESTERN CONUS BY THIS WEEKEND...LEADING TO
BUILDING HEIGHTS/WARMTH THROUGH THE GREAT LAKES. BUT WITH THE
BUILDING HEIGHTS/MOISTURE GRADIENT SITTING ACROSS THE GREAT LAKES
INTO THE MIDWEST...THE BIGGEST FORECAST CHALLENGE THROUGH THE
WEEKEND WILL CONTINUE TO BE DAILY PRECIP CHANCES.

FRIDAY AND FRIDAY NIGHT...SFC WARM FRONT WILL REMAIN DRAPED FROM THE
MIDWEST INTO THE OHIO VALLEY WITH THE GRADIENT OF MOISTURE/
INSTABILITY FROM WESTERN UPPER MICHIGAN DOWN THROUGH LOWER MICHIGAN.
WILL LIKELY BE ANOTHER ROUND OF CONVECTION ONGOING FRIDAY MORNING
ALONG THAT GRADIENT ALTHOUGH THE EXACT LOCATION OF DEVELOPMENT LATER
TONIGHT REMAINS UNCERTAIN AT THIS POINT...WHICH OF COURSE WILL
IMPACT WHERE IT ENDS UP. RIGHT NOW...BELIEVE MOST OF THE ACTIVE
WEATHER WILL OCCUR WEST AND SOUTH OF THIS CWA ALONG A LINE FROM NRN
WISCONSIN DOWN THROUGH CENTRAL AND SRN LOWER MICHIGAN...GRAZING OUR
SRN COUPLE TIER OF COUNTIES FRIDAY MORNING. BUT IT/S ALSO POSSIBLE
CONVECTION TAKES OFF FURTHER SOUTH FROM IOWA INTO THE OHIO VALLEY
PRETTY MUCH MISSING NRN MICHIGAN ALTOGETHER. WILL HOLD ON TO CHANCY
POPS FRIDAY MORNING ACROSS THE SW THIRD OF THE CWA. AFTER MORNING
CONVECTION...CLOUD COVER THINS OUT FOR THE AFTERNOON HOURS WITH
TEMPERATURES WARMING TO THE MID 70S TO LOWER 80S AND DEWPOINTS IN
THE MID TO UPPER 60S. MOISTURE POOLING/INSTABILITY AND LOW LEVEL
CONVERGENCE THIS GO AROUND LOOKING TO SET UP ACROSS THE SW COUNTIES
WHERE THERE MAY BE A FEW AFTERNOON/EARLY EVENING SHOWERS OR ROGUE
THUNDERSTORM. CHANCES ARE NOT GREAT...BUT ENOUGH TO RETAIN LOW POPS
IN THE FORECAST. DRY LATER FRIDAY NIGHT WITH PATCHY FOG A GOOD BET
ONCE AGAIN.

WEEKEND FORECAST...GUIDANCE CONSENSUS HAS PRETTY MUCH FALLEN IN LINE
WITH THE IDEA OF SHORT WAVE TROUGHINESS DEEPENING ACROSS THE NRN/
CENTRAL ROCKIES WHILE SHARP DOWNSTREAM RIDGE AXIS POKES UP INTO THE
GREAT LAKES...SATURDAY THROUGH SUNDAY. HAVE BECOME INCREASINGLY
CONVINCED THAT MUCH IF NOT ALL OF THE WEEKEND WILL TURN OUT WARM BUT
PRECIP-FREE AT LEAST FOR 95 PERCENT OF THE CWA...WHILE BULK OF THE
WEATHER "ACTION" GETS RE-FOCUSED FROM THE CENTRAL PLAINS INTO THE
UPPER MIDWEST AS ONE OR MORE WAVES RIDE UP THROUGH THAT REGION. BUT
WITH WARM AND RELATIVELY HUMID CONDITIONS ACROSS THE STATE...COULD
THERE BE A FEW POP-UP SHOWERS EITHER DAY...YES. BUT JUST NOT FEELING
GOOD ABOUT HAVING SUCH A WET LOOKING FORECAST WHEN I/M REASONABLY
CONVINCED THAT MOST LOCATIONS REMAIN DRY. SO...HAVE REDUCED POPS TO
JUST SLIGHT CHANCE (20) FOR BOTH SATURDAY AND SUNDAY WHICH DOES NOT
SHOW UP IN THE ZONE FORECAST PRODUCT BEYOND DAY 2. TEMPS...UPPER 70S
TO MIDDLE 80S BOTH DAYS BUT HIGHER DEWPOINTS IN THE 60S WILL MAKE
THINGS FEEL A BIT UNCOMFORTABLE.

MONDAY THROUGH THURSDAY...SHORT WAVE TROUGH IN THE ROCKIES LOOKING
TO DISLODGE AND ADVANCE INTO THE UPPER MIDWEST/GREAT LAKES
MIDWEEK...PUSHING A COLD FRONT THROUGH THE REGION AND KNOCKING
TEMPERATURES BACK DOWN TO AOB NORMAL READINGS. MEANWHILE...SHARP
UPPER RIDGING ACROSS THE GREAT LAKES SLIPS EAST OF THE STATE FOR
MONDAY AND TUESDAY AND WILL OPEN THE DOOR JUST A LITTLE BIT MORE TO
PRECIP CHANCES FOR BOTH MONDAY AND TUESDAY. GREATER PRECIP CHANCES
COME LATE TUESDAY THROUGH WEDNESDAY WITH FROPA BEFORE THINGS DRY OUT

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 700 PM EDT THU AUG 21 2014

CONDITIONS WILL AGAIN DETERIORATE TO MVFR/IFR LATER THIS EVENING
AND OVERNIGHT AS LOW STRATUS AND AREAS OF FOG DEVELOP AS THE
BOUNDARY LAYER COOLS. SCT/NMRS SHOWERS WILL IMPACT MAINLY SW
PORTIONS OF NRN LWR MICHIGAN AROUND TVC AND MBL LATER THIS EVENING
THRU EARLY FRIDAY ALONG THE NE EDGE OF MOISTURE AND INSTABILITY
ASSOCIATED WITH UPSTREAM LOW PRESSURE. AN ISOLD THUNDERSTORM IS
ALSO POSSIBLE IN THESE AREAS...BUT WILL LEAVE OUT OF THE TAF FOR
NOW. WINDS WILL REMAIN MOSTLY LIGHT/VARIABLE THRU THE 24 HR
FORECAST PERIOD.

&&

.MARINE...
ISSUED AT 356 PM EDT THU AUG 21 2014

MARINE...LIGHT EAST WIND REGIME TO CONTINUE INTO THIS WEEKEND. MAIN
FOCUS FOR SHOWERS AND STORMS EXPECTED TO STAY OFF TO OUR SOUTH AND
WEST FOR THE NEXT SEVERAL DAYS...WITH THE BEST CHANCE FOR ANY
SHOWERS AND STORMS ACROSS THE NORTHERN LAKES TONIGHT INTO FRIDAY
MORNING...ALTHOUGH NO SIGNIFICANT WIND GUSTS OR RAINS ARE EXPECTED.
WILL NEED TO WATCH FOG POTENTIAL HEADING INTO THIS WEEKEND AS WARM
AND INCREASINGLY MOIST AIR OVERSPREADS THE STILL COOL LAKE
WATERS.

&&

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

&&

$$

SYNOPSIS...MG
SHORT TERM...MSB
LONG TERM...ADAM
AVIATION...MR
MARINE...MSB





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