Area Forecast Discussion
Issued by NWS Marquette, MI

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000
FXUS63 KMQT 310830
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
430 AM EDT MON AUG 31 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 422 AM EDT MON AUG 31 2015

RAP ANALYSIS AND WATER VAPOR IMAGERY SHOWS THE UPPER GREAT LAKES
REGION BEING JUST TO THE EAST OF AN UPPER RIDGE AXIS STRETCHING FROM
JUST WEST OF THUNDER BAY TO THE MID MISSISSIPPI VALLEY. TO THE
SOUTHEAST...A HIGH IS CENTERED NEAR THE CENTRAL APPALACHIANS AND
WILL REMAIN THAT WAY THROUGH MUCH OF THE WORK WEEK. THIS PLACES THE
CWA ON THE NORTHWESTERN EDGE OF A RIDGE ASSOCIATED WITH THE HIGH AND
UNDER ABUNDANT DRY AIR AS SEEN ON THE 00Z KGRB SOUNDING. OTHER THAN
A FEW HIGH CLOUDS ROUNDING THE UPPER RIDGE AND MOVING ACROSS THE
AREA...THAT DRY AIR AND AND GENERALLY LIGHT WINDS HAVE LEAD TO
RADIATIONAL COOLING OVER MUCH OF THE CWA AND LOWERED 3AM
TEMPERATURES TO THE LOWER 60S. WITH DEWPOINTS AROUND THOSE
VALUES...FOG HAS DEVELOPED OVERNIGHT OVER THE EAST AND WAS AIDED BY
THE SLIGHT MOISTENING OFF LAKE MICHIGAN. ADDITIONAL FOG AND STRATUS
HAS DEVELOPED IN NORTH CENTRAL WISCONSIN AND HAS BE NOSING NORTHEAST
ACROSS THE BORDER AT TIMES. EXPECT THE FOG TO GRADUALLY LIFT TO A
STRATUS DECK THROUGH THE MORNING HOURS...DUE TO THE 10-15KT
SOUTHWESTERLY FLOW JUST ABOVE THE SURFACE...AND EVENTUALLY SCATTER
OUT IN THE AFTERNOON.

FOR THE REST OF TODAY...THE UPPER RIDGE WILL MOVE EAST ACROSS THE
AREA WHILE A SURFACE LOW NEAR LAKE WINNIPEG WILL BEGIN TO LIFT
NORTHEAST INTO ONTARIO IN RESPONSE TO THE FAST MOVING SHORTWAVE
CURRENTLY IN MONTANA. OTHER THAN THE DIURNAL CLOUDS ASSOCIATED WITH
THE FOG BURNING OFF...ONLY EXPECT HIGH CLOUDS TO STREAM ACROSS THE
AREA THROUGH THE DAY TODAY. SOUTHWESTERLY FLOW WILL CONTINUE TODAY
AHEAD OF THE TRAILING/WEAKENING SURFACE TROUGH THAT IS MOVING EAST
ACROSS MINNESOTA. EXPECT WINDS TO STAY BELOW 15-17KTS FOR MOST OF
THE AREA...BUT THE INCREASING LOW LEVEL WINDS TOWARDS KIWD WILL
LIKELY PUSH GUSTS UP TO AROUND 20KTS IN THE AFTERNOON. HIGHS TODAY
LARGELY DEPEND ON THE AMOUNT OF MIXING...AS NAM/GFS DIFFER SOME DUE
TO THE FOG AND STRATUS THIS MORNING...ALTHOUGH STILL THINK THERE
SHOULD BE ENOUGH MIXING TO TAP INTO THE VERY WARM AIR ALOFT. GFS HAS
MIXING ALMOST TO 850MB (TEMPS THERE RIGHT AROUND 22C)...WHICH WOULD
LEAD TO HIGHS IN THE UPPER 80S. WITH DOWNSLOPING FLOW OVER THE NORTH
CENTRAL AND NEAR THE BARAGA PLAINS...WOULD EXPECT TO SEE A FEW SPOTS
REACHING 90 DEGREES THIS AFTERNOON.

THE SURFACE LOW WILL QUICKLY MOVE INTO SOUTHERN HUDSON BAY TONIGHT
AND DRAG A DECAYING TROUGH EAST ACROSS NORTHWESTERN LAKE SUPERIOR
OVERNIGHT. MODELS ARE SHOWING A THIN RIBBON OF MOISTURE ALONG THE
TRAILING/WEAKENING TROUGH...ESPECIALLY ABOVE 650MB...WHILE THERE ARE
SOME HINTS OF A POCKET OF 925-850MB MOISTURE PIVOTING NORTH-
NORTHEAST INTO THE AREA TONIGHT. LOOKING IN THAT AREA (MISSOURI)
RIGHT NOW...THERE ISN/T MUCH THERE FOR CLOUDS OR SHOWERS. IN
ADDITION...LATE TONIGHT AND INTO TUESDAY...A SHORTWAVE FROM WESTERN
COLORADO MOVES UP INTO THE AREA. DUE TO THE HEIGHT OF THE
MOISTURE...HAVE SOME CONCERN ON THE AMOUNT/COVERAGE OF SHOWERS OVER
WESTERN LAKE SUPERIOR OVERNIGHT...BUT FELT THE POSSIBILITY OF THE
SHORTWAVE...MOISTURE AND STEEPER 600-400MB LAPSE RATES WERE ENOUGH
TO SUPPORT SLIGHT CHANCES. THOSE STEEPER LAPSE RATES DO PRODUCE SOME
ELEVATED INSTABILITY AND AT THAT LEVEL THINK THUNDER POTENTIAL IS
PRETTY LOW. BUT THE STEEPER LAPSE RATES ARE ENOUGH TO MATCH THE
THUNDER TO THE POPS ALTHOUGH CONFIDENCE ON THUNDER IS VERY LOW.
FINALLY...CONTINUED TO MENTION PATCHY FOG OVER THE CENTRAL/EASTERN
CWA TONIGHT DUE TO THE CONTINUED INDICATION IN THE MODELS FOR ENOUGH
COOLING BELOW THE NOCTURNAL INVERSION TO SUPPORT LIGHT ENOUGH WINDS
AND FOG DEVELOPMENT. DO HAVE TO WONDER THOUGH IF WINDS WILL BE
STRONG ENOUGH TO LIMIT THE FOG TO ONLY THE SHELTERED AREAS.

.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 428 AM EDT MON AUG 31 2015

NO BIG CHANGES TO THE OVERALL IDEA OF LATE SUMMER RIDGING DOMINATING
INTO NEXT WEEKEND. TROUGHING ALOFT WITH MUCH COOLER CONDITIONS STILL
ON TRACK TO ARRIVE AROUND LABOR DAY.

RIDGE ALOFT FLATTENS OUT SLIGHTLY TUE INTO WED WHICH ALLOWS WEAK
SHORTWAVES TO CROSS THE REGION AND AT LEAST SOME CHANCES OF RAIN.
STRONGEST WAVE BY FAR STAYS OVER NORTHERN ONTARIO WITH ASSOCIATED
SFC LOW...BUT THERE IS STILL HINT FM MODELS THAT TAIL OF THAT
SHORTWAVE OR ADDITIONAL MINOR WAVES LIFTING IN FM THE
SOUTHWEST...AND ASSOCIATED SUBTLE H7-H5 Q-VECTOR CONVERGENCE WILL
COMBINE WITH WEAK SFC TROUGH AND LAKE BREEZES TO DEVELOP A FEW
SHRA/TSRA. WITH HEIGHTS LOWERING ALSO CANNOT DISCOUNT IDEA SHOWN BY
NAM/GEM-REGIONAL THAT ISOLD SHRA COULD WORK IN AS EARLY AS THE
MORNING AS WEAK SHORTWAVES SLIDING THROUGH COMBINE WITH MOISTURE
ADVECTION AT H85. GEM-REGIONAL SHOWS QPF OVER KEWEENAW 12Z-15Z WHICH
IS ALSO SUPPORTED BY LATEST NCAR ENSEMBLES. OVERALL THOUGH...LACKING
DEEPER MOISTURE AS SEEN IN FORECAST SOUNDINGS WILL BE LIMITING
FACTOR FOR MUCH PRECIP. TSRA CHANCES PROBABLY TOP OUT DURING PEAK
HEATING OF DAY...BUT WITH 1-6KM MUCAPE OVER 500J/KG POKING IN OVER
WESTERN CWA IN THE MORNING...CANNOT COMPLETELY RULE OUT. IF A TSRA
COULD FORM...ESPECIALLY DURING PEAK HEATING OF AFTN...COULD SEE AN
ISOLD STRONGER STORM WITH MLCAPES TO AROUND 1000J/KG AND DEEP LAYER
SHEAR 30+ KTS. SMALL DCAPES AND WBZERO HEIGHTS TO 12KFT WOULD SUPPORT
ONLY A MARGINAL HAIL RISK. LIGHTNING AND HEAVY DOWNPOURS WOULD BE
MAIN HAZARDS. STORM MOTION WOULD BE FM WEST TO EAST AT 25-30 KTS.
BASED ON H85 TEMPS AROUND 18C WILL GO FOR HIGHS IN THE MID 80S...DOWN
SOME FM THE LOW 90S FORECAST TODAY.

WEAKNESS IN RIDGE STILL THERE FOR WED AND WED NIGHT SO MAY SEE
ANOTHER OPPORTUNITY FOR SOME SHRA/TSRA. WEAK LARGE SCALE SUPPORT AND
MARGINAL MOISTURE WILL CONTINUE TO LIMIT COVERAGE. BEST CHANCE OF
SHRA/TSRA SHOULD BE DURING PEAK HEATING ON WED AFTN. THEN INTO WED
NIGHT...BASED ON ITS OWN FORECAST SOUDNINGS...LAST COUPLE RUNS OF
GFS SEEM TOO AMBITIOUS SHOWING WIDESPREAD LIGHT QPF IN ARC FM CNTRL
MANITOBA/NORTHWEST ONTARIO TO THE UPPER GREAT LAKES. SOUNDINGS SHOW
A LOT OF DRY AIR BLO H6 AND THE MID LEVEL RH SUGGESTS MAYBE BKN
CLOUDS BUT NOT A LOT OF PRECIP. WILL FOLLOW THE DRIER NAM/GEM-
NH/ECMWF WITH ONLY SCATTERED MID CLOUDS. HEAT CONTINUES WITH
READINGS ON WED REACHING BACK TOWARD 90 DEGREES OVER WEST AND MID-
UPR 80S ELSEWHERE AWAY FM LK MICHIGAN. DEVELOPING SSE WINDS WILL
KEEP IMMEDIATE LAKE SUPERIOR SHORE FM KEWEENAW TO BIG BAY/MARQUETTE
A SHADE COOLER.

SHORTWAVE WORKING ACROSS UPPER GREAT LAKES THURDAY APPEARS TO STAY
SOUTH OF UPR MICHIGAN AT LEAST RIGHT NOW. CHANCES OF SHRA/TSRA WILL
BE LOW...BUT WILL KEEP SLIGHT CHANCES DURING PEAK HEATING ON THU
AFTN. TEMPS ON THU MID 80S TO NEAR 90...SIMILAR TO READINGS ON WED
WITH MINIMAL CHANGE IN H85 TEMPS OF 18-20C. UPPER RIDGE BUILDS BACK
OVER GREAT LAKES ON FRIDAY SO ANY SHORTWAVES WORKING THROUGH BY THAT
TIME SHOULD BE WEAK. WITHOUT MUCH LARGE SCALE SUPPORT...SHRA/TSRA
SHOULD BE TIED TO EDGE OF STRONGEST INSTABILITY EXPANDING FM THE
PLAINS. REMNANTS OF THIS ACTIVITY MAY TRY TO MAKE IT OVER UPPER
GREAT LAKES LATER FRIDAY INTO SATURDAY. TIME FRAME SEEMS LIKE IT
WILL END UP MOSTLY DRY THOUGH. HIGH TEMPS SIMILAR TO WED AND THU.

GFS AND ECMWF/GEM-NH SHOW DIFFERENCES FOR THE UPCOMING WEEKEND.
MAIN ISSUE IS HOW QUICKLY COLD FRONT THAT USHERS IN MUCH COOLER
CONDITIONS WILL ARRIVE. AS THE FRONT DRAWS CLOSER MAY SEE BETTER
CHANCES OF SHRA/TSRA OVER AT LEAST WESTERN CWA ON SATURDAY. HEAT
CONTINUES WITH HIGHS AGAIN UPR 80S TO AROUND 90 DEGREES. GFS HAS
BACKED AWAY FM THE 22-24C H85 TEMPS IT SHOWED YDY...SO PROBABLY
LOOKING AT MAX TEMPS INTO THE LOWER 90S AT THE WARMEST. GFS MUCH
QUICKER SHOWING FRONT MOVING THROUGH ON SUNDAY WHILE ECMWF IS
STRONGER WITH UPPER RIDGE AND DOES NOT BRING THE FRONT THROUGH
UNTIL MONDAY. TYPICALLY THE STRONGER RIDGE WINS OUT. AT THIS POINT
WILL NOT STRAY FM MODEL CONSENSUS WHICH RESULTS IN LOW CHANCE POPS
FOR SUNDAY.
&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 119 AM EDT MON AUG 31 2015

A THIN LAYER OF SMOKE ALOFT IS TOO HIGH TO BE INCLUDED IN THE
TAFS...OTHERWISE VFR CEILINGS AND VIS SHOULD CONTINUE. THERE IS
AGAIN A SMALL CHANCE OF MAINLY MVFR VIS WITH FOG DEVELOPING AT IWD
AND MORE LIKELY SAW NEAR DAYBREAK MONDAY. ALTHROUGH THERE SHOULD BE
A LITTLE MORE WIND TO CONTEND WITH TONIGHT...FOG WILL STILL BE
POSSIBLE.
&&

.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 422 AM EDT MON AUG 31 2015

EXPECT SOUTH-SOUTHWESTERLY WINDS TO CONTINUE OVER LAKE SUPERIOR
THROUGH MUCH OF THE WORK WEEK...AS THE AREA IS ON THE NORTHWESTERN
EDGE OF A HIGH PRESSURE RIDGE CENTERED OVER THE CENTRAL
APPALACHIANS. THERE WILL BE A BRIEF INCREASE IN THE SOUTHWESTERLY
WINDS TONIGHT...UP TO 20KTS...AS A LOW PRESSURE SYSTEM MOVES FROM
LAKE WINNIPEG AND NORTH DAKOTA TO SOUTHERN HUDSON BAY BY TUESDAY
MORNING. AT THIS TIME...THE MARINE LAYER SHOULD KEEP THE WINDS IN
CHECK...BUT COULD SEE HIGHER GUSTS TO 25 OR EVEN 30KTS AT A FEW OF
THE HIGHER PLATFORMS TOWARDS ISLE ROYALE. OTHERWISE...EXPECT WINDS
TO BE BELOW 20KTS FOR THE REST OF THE PERIOD.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&

$$

SHORT TERM...SRF
LONG TERM...JLA
AVIATION...07
MARINE...SRF



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