Area Forecast Discussion
Issued by NWS Gaylord, MI

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000
FXUS63 KAPX 241058
AFDAPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
658 AM EDT SUN AUG 24 2014

.SYNOPSIS...
ISSUED AT 308 AM EDT SUN AUG 24 2014

HIGH PRESSURE TO OUR EAST WILL PROVIDE FOR LIGHT SOUTHERLY
BREEZES...AND INCREASING WARMTH AND HUMIDITY THROUGH MONDAY. CHANCES
FOR SHOWERS AND THUNDERSTORMS WILL START TO INCREASE LATE
TONIGHT...AND PERSIST OFF AND ON THROUGH THE UPCOMING WORK WEEK.
MONDAY LOOKS TO BE THE WARMEST DAY OF THE WEEK...WITH COOLER WEATHER
TO FOLLOW.

&&

.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 308 AM EDT SUN AUG 24 2014

HIGH IMPACT WEATHER POTENTIAL: MINIMAL

PRIMARY FORECAST CHALLENGES: DO SHOWERS MOVE INTO NORTHERN MICHIGAN?

CURRENTLY, THERE IS A RIDGE AT 500 MB OVER THE UPPER GREAT LAKES
THIS HAS BEEN ABLE TO KEEP MOST OF THE PRECIPITATION OUT OF THE
REGION. THE ONLY EXCEPTION WAS THE MCS THAT MOVED THROUGH WISCONSIN
AND INTO INDIANA. THIS LEFT A MESOSCALE VORT OVER E WISCONSIN THAT
OVER THE LAST FEW HOURS HAS BEEN PRODUCING RAIN SHOWERS NEAR MKE.
HOWEVER, UNDER THE RIDGE THE FLOW HAS BEEN SUCH THAT MOST SHOWERS
HAVE NOT GONE ANYWHERE. OTHERWISE, THE MAIN CONCERN TO THE FORECAST
WILL BE THE SFC LOW IN THE DAKOTAS AND THE 500 MB TROUGH THAT IS
DIGGING JUST TO THE WEST OF IT, AND THE TIMING OF THE RAIN FROM IT.

TODAY...THE MCV NEAR MKE IS EXPECTED TO MOVE NE INTO W LOWER DURING
THE DAY AND BRING THE MOISTURE THAT IS RIDING ALONG IT AND THE 850
MB WARM FRONT THAT WILL MOVE THROUGH THE STATE TODAY. AS WE HAVE
SEEN WITH MOST PRECIPITATION OVER THE LAST FEW DAYS, THIS WILL MAKE
A LIMITED AMOUNT OF RAIN TO SUCH A SMALL AREA, THAT IS POSSIBLE THAT
THE ISOLATE TO SCATTERED RAIN WORDING ALONG THE M-55 CORRIDOR MAY BE
OVERDONE. HOWEVER, ALL OF THE MODELS TAKE THIS FEATURE AND MOVE IT
ACROSS THE STATE BY 00Z. THE GFS WHILE IT BRINGS RAIN ONSHORE, IS
THE ONLY ONE THAT WASHES OUT THE CHANCES FOR RAIN GOING INTO THE
AFTERNOON, WHILE THE NAM12 AND ECMWF CONTINUE TO HAVE CHANCES ALONG
AND SOUTH OF THE M-55.

NUMBERS SEEMED A LITTLE LOW BASED ON WHAT HAPPENED YESTERDAY FOR
TEMPERATURES. THINK THAT WITH THE 850 MB TEMPERATURES EXPECTED TO
WARM TO 16-17C BY THE AFTERNOON, AND WITH THE SUNSHINE FILTERED
THROUGH MOSTLY HIGH CLOUDS, THAT THE LOWER 80S ARE MORE LIKELY THAN
THE UPPER 70S. SO HAVE KEPT THE TEMPERATURES FROM THE PREVIOUS
FORECAST.

TONIGHT...THE MCV FROM THE DAY CONTINUES TO MOVE OFF THE LAKE HURON
SHORE, AND WILL BRING SOME SHOWERS ALONG THE M-55 CORRIDOR FOR THE
EVENING. THEN THE CONCERN SHIFTS BACK TO THE WEST. THE GFS HAS SOME
SORT OF LINE THAT IS ALMOST INTO NW LOWER BY 06Z. THINK THAT THE
ECMWF IS A LITTLE MORE REALISTIC AS THE 500 MB RIDGE IS STILL SLOW
TO ALLOW A WHOLE LOT OF RAIN TO GET THAT FAR EAST WITH THE MAJORITY
OF THE DYNAMIC FORCING STILL OVER MINNESOTA AND W WISCONSIN. THE NAM
IS EVEN MORE AGGRESSIVE WITH RAIN TO I-75 BY 12Z AND BRINGING THE
JET OVER THE UPPER GREAT LAKES BY THEN. SO AM GOING WITH THE SLOWER
ECMWF IDEA.

FOG WILL AGAIN BE PRESENT, ESPECIALLY IN THE EAST UNTIL THE GRADIENT
BEGINS TO TIGHTEN UP ENOUGH TO REALLY GET THE RETURN FLOW GOING.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 308 AM EDT SUN AUG 24 2014

...WARM AND STICKY MONDAY BEFORE COOLING OFF SOME...

A PERIOD OF INCREASINGLY ACTIVE WX LOOKS TO GET STARTED ON MONDAY.
PROBABLY. THE UPPER RIDGE NOW OVERHEAD WILL BE SUPPRESSED BY
EJECTING UPPER LOW...WHICH CROSSES FAR NORTHERN ONTARIO MONDAY
NIGHT. THAT FLATTENS OUT AND ACCELERATES THE 500MB FLOW ACROSS THE
NORTHERN LAKES. IT ALSO SLOWLY PUSHES A COLD FRONT ACROSS NORTHERN
MI LATE MONDAY NIGHT THRU TUESDAY. THIS FRONT WILL ALMOST EXIT THE
STATE TO THE SOUTH BY WED MORNING. PRECIP TRENDS ARE THE MAIN
FORECAST CHALLENGE.

THE NAM HAS ALL SORTS OF FEEDBACK ISSUES IN THE INITIAL 24-36
HOURS...AND HAS BEEN LARGELY IGNORED IN THE MAKING OF THIS FORECAST.

MONDAY...1001MB LOW MOVES FROM NE OF WINNIPEG TO W OF JAMES
BAY...WITH THE ASSOCIATED COLD FRONT ADVANCING ACROSS WI. WE NO
LONGER HAVE RIDGING POKING INTO THE REGION FROM THE EAST...AND OUR
SUB-850MB FLOW FINALLY GETS A CHANCE TO VEER SW. THESE WINDS ARE NOT
STRONG...15-20KT AT 950MB AND 850MB...BUT THEY WILL BRING IN A MORE
HUMID AND POTENTIALLY MORE UNSTABLE AIRMASS. SURFACE DEW POINTS
SHOULD CLIMB INTO THE MID 60S IN EASTERN UPPER...THE UPPER 60S IN
NORTHERN LOWER. STICKY.

A SUBSTANTIAL MID-LEVEL DRY SLOT ADVANCES ACROSS CENTRAL/SOUTHERN
MN...NORTHERN WI...AND UPPER MI AS THE DAY PROGRESSES. THIS WON/T
HAVE A LARGE IMPACT FOR US...OTHER THAN TO PERHAPS SHUT DOWN POPS IN
EASTERN UPPER AS THE AFTERNOON PROCEEDS. TO THE SOUTH OF THIS AND
AHEAD OF THE COLD FRONT...THE AIRMASS IS SLUDGY ENOUGH THAT THE
AMOUNT OF SUNSHINE WE SEE IS UNCERTAIN. DECAYING UPSTREAM CONVECTION
COULD RESULT IN SOME SHRA IN WESTERN/NORTHERN SECTIONS IN THE
MORNING...AND WILL RESULT IN A CONSIDERABLE AMOUNT OF CLOUD COVER.
BUT WE MIGHT BE ABOVE TO MUSTER ENOUGH HEATING IN THE AFTERNOON TO
ALLOW FOR SCT SHRA/TSRA TO REDEVELOP. AN 86/68 PARCEL HAS OVER
1500J/KG OF MLCAPE...BUT STILL 30-40J/KG OF CIN (THANKS TO 850MB
TEMPS OF 19C). THERE ARE NO OBVIOUS TRIGGERS...BUT DIFFERENTIAL
HEATING BOUNDARIES MAY BE LURKING AFTER ANY MORNING ACTIVITY...AND
LAKES BREEZES WILL TRY TO MAKE SOME INLAND PROGRESS WITH MARGINAL
950MB WINDS IN PLACE. IF WE DO FIRE ANYTHING...WIND FIELDS/SHEAR ARE
HIGHLY UNIMPRESSIVE...YOU HAVE TO GO ABOVE 500MB TO WINDS ABOVE
20KT. STILL...CAN/T RULE OUT A PULSE SVR THREAT GIVEN THE
INSTABILITY THAT IS POTENTIALLY AVAILABLE (PER SPC DAY 2 OUTLOOK).

HIGHS WILL REACH INTO THE 80S. NOT IMPOSSIBLE FOR A FEW SPOTS IN
NORTHERN LOWER TO TOUCH 90F...BUT IN GENERAL AM LEANING TOWARD THE
SLIGHTLY COOLER MAV GUIDANCE.

MON NIGHT/TUESDAY...CONTINUES TO LOOK AS THOUGH MONDAY NIGHT WILL BE
A RELATIVE LULL. SOME DIURNAL CONVECTION WILL LINGER INTO
EVENING...MAINLY IN EASTERN SECTIONS. ACTIVITY MAY ALSO ARRIVE FROM
THE WEST VERY LATE IN ASSOCIATION WITH THE SURFACE COLD FRONT. SAID
FRONT AND THE ADDITION OF DIURNAL HEATING WILL RESULT IN INCREASING
POPS AGAIN ON TUESDAY...ESPECIALLY IN THE SE HALF OF THE FORECAST
AREA. MIN TEMPS WILL BE IN THE 60S...THOUGH A FEW SPOTS IN NORTHERN
LOWER MAY HOVER AROUND 70F. MAX TEMPS WILL RANGE FROM 70-75 EASTERN
UPPER...TO THE MID 80S NEAR SAGINAW BAY.

REST OF THE FORECAST...THE ECMWF IS MORE AGGRESSIVE THAN THE GFS IN
DIGGING A LOW-AMPLITUDE NORTHERN STEAM SHORTWAVE INTO THE NORTHERN
LAKES ON WEDNESDAY. THOUGH THIS COULD CONTRIBUTE TO A SHRA THREAT
TUE NIGHT...IT ALSO DISPLACES THE FRONTAL ZONE FURTHER SOUTH...
LEAVING THE MID-WEEK COMPLETELY DRY. (IN CONTRAST...AT THIS TIME
YESTERDAY OUR ALL-MODEL BLEND WAS SPITTING OUT LIKELY POPS FOR
WEDNESDAY.) THIS ISN/T A UNANIMOUS OPINION...THE GFS REMAINS
LOWER-AMPLITUDE...LEAVES THE FRONT HUNG UP IN MI...AND WOULD PRODUCE
A RATHER WET WED AFTERNOON/WED NIGHT. FOR NOW...THIS PERIOD IS
UNCERTAIN ENOUGH TO WARRANT CHANCY POPS FOR MUCH OF IT...BUT IN
GENERAL WILL BE TRENDING POPS A LITTLE LOWER THAN THEY WERE
PREVIOUSLY.

TEMPS WILL CONTINUE TO HEAD DOWNHILL ON WED...THOUGH HOW MUCH IS
SOMEWHAT UNCERTAIN GIVEN THE MODEL DISAGREEMENTS. BUT IN
GENERAL...TEMPS SHOULD SETTLE IN A BIT BELOW CLIMO BY THU/FRI.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 657 AM EDT SUN AUG 24 2014

ANOTHER MORNING OF STRATUS AND SOME FOG.

ALL SITES NOW SEEING IFR CIGS IN STRATUS. MBL/TVC ARE ON THE EDGES
OF THE CLOUD DECK...AND WILL ONLY HAVE TO DEAL WITH IT INTO MID
MORNING. PLN AND ESPECIALLY APN WILL HAVE RESTRICTIONS FOR A
LONGER PERIOD OF TIME...INTO AFTERNOON AT APN. SHOULD NOT HAVE AS
MUCH OF THIS TONIGHT...WITH A BIT MORE IN THE WAY OF CLOUD COVER
AND LOW-LEVEL WINDS.

SURFACE WINDS WILL BE LIGHT E TO SE TODAY...LIGHT TONIGHT.

&&

.MARINE...
ISSUED AT 308 AM EDT SUN AUG 24 2014

WINDS WILL CONTINUE TO BE LIGHT AND OUT OF THE E OR SE
TODAY WITH THE WINDS BEGINNING TO PICK UP OVER THE LAKES, HOWEVER,
WILL CONTINUE TO BE UNDER SMALL CRAFT CONDITIONS. THE WINDS WILL
BEGIN TO VEER TO THE SOUTH TONIGHT, BUT NOT EXPECTING THE GRADIENT
TO TIGHTEN UP UNTIL MONDAY AS THE FRONT APPROACHES. HOWEVER, BY
MONDAY NIGHT, THE GRADIENT RELAXES AS THE FRONT MOVES THROUGH.


&&

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

&&

$$

SYNOPSIS...JZ
SHORT TERM...JL
LONG TERM...JZ
AVIATION...JZ
MARINE...JL






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