Area Forecast Discussion
Issued by NWS Marquette, MI

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS63 KMQT 312021
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
421 PM EDT MON AUG 31 2015

.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 418 PM EDT MON AUG 31 2015

WV IMAGERY AND RAP ANALYSIS INDICATED A PROMINENT MID/UPEPR LEVEL
RIDGE FROM NM INTO THE GREAT LAKES RESULSTING IN SW FLOW FROM THE
CNTRL ROCKIES INTO THE UPPER MS VALLEY. A WELL-DEFINED SHORTWAVE
TROUGH OVER SRN MANITOBA WAS LIFTING TO THE NE. AT THE SFC...SSW
FLOW PREAVILED ACROSS THE UPPER MS VALLEY AND WRN ALKES BETWEEN HIGH
PRES OVER THE CNTRL LAKES AND A COLD FRONT EXTENDING FROM THE SE
CORNER OF MANITOBA INTO ERN SD. MOST OF THE FOG FROM EARLIER TODAY
HAS BURNED OFF EXCEPT OVER THE FAR SE ALONG LAKE MI NEAR KISQ.
OTHERWISE...MOSTLY SUNNY SKIES PREVAILED WITH TEMPS AWAY FROM LAKE
MI INTO THE MID TO UPPER 80S.

TONIGHT...SEVERAL MODELS SUGGEST SOME SHRA/TSRA MAY DEVELOP FROM MN
INTO NW WI OR WRN LAKE SUPEROR AS AN AXIS OF HIGHER MOISTURE AND THE
TAIL OF THE MANITOBA SHRTWV SLIDES TO THE EAST. HOWEVER...THE AMOUNT
OF CAPPING AND ONLY WEAK MID LEVEL QVECTOR CONV...EXPECT ANY
COVERAGE TO BE MINIMAL AND REMAIN TO THE WEST OF THE CWA. ALTHOUGH
BNDRY LAYER WINDS WILL BE HIGHER THAN LAST NIGHT...EXPECT PATCHY/AREAS
TO REDEVELOP OVER MAINLY THE SE HALF.

TUE...PCPN CHANCES WILL INCREASE AS THE MOISTURE AXIS AND WEAK
TROUGH SAG INTO UPPER MICHIGAN. ALTHOUGH SOME PCPN MAY BE POSSIBLE
IN THE MORNING...EXPECT BETTER SHRA/TSRA CHANCES BY AFTERNOON WITH
INCREASED DAYTIME HEATING AND SUPPORT FROM DEVELOPING LAKE BREEZE
BOUNDARIES. TSRA WILL BE POSSIBLE WITH MLCAPE VALUES INTO THE 1K-2K
J/KG RANGE. HOWEVER WITH 0-6KM SHEAR VALUES ONLY AROUND 25-30 KNOTS
AND WITH WBZ HEGHTS NEAR 13K FT...SEVERE TS CHANCES WILL BE MINIMAL.
THE MAIN HAZARDS WILL BE BRIEF HEAVY RAIN AND GUSTY WINDS. EVEN WITH
INCREASED CLOUD COVER...TEMPS SHOULD AGAIN CLIMB INTO THE MID TO
UPPER 80S.

.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 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 741 AM EDT MON AUG 31 2015

PATCHY GROUND FOG IS AFFECTING KSAW/KCMX AT THE START OF THE TAF
PERIOD...BUT STRONGER WINDS ALOFT AND DIURNAL HEATING SHOULD
QUICKLY DISSIPATE THE FOG THIS MORNING. OTHERWISE...EXPECT VFR
CONDITIONS TO PREVAIL AT THE SITES THROUGH MUCH OF THE REST OF THE
PERIOD. A WEAK TROUGH WILL NEAR THE WESTERN SITES LATE TONIGHT AND
COULD PRODUCE SOME SPRINKLES...WITH KSAW ONCE AGAIN SEEING THE
POTENTIAL FOR PATCHY GROUND FOG (ALTHOUGH WINDS ABOVE THE SURFACE
WILL BE A TOUCH STRONGER).
&&

.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 418 PM EDT MON AUG 31 2015
EXPECT SOUTH-SOUTHWESTERLY WINDS TO CONTINUE OVER LAKE SUPERIOR
THROUGH MUCH OF THE 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 THROUGH NW
ONTARIO TO SOUTHERN HUDSON BAY BY TUE 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...JLB
LONG TERM...JLA
AVIATION...SRF
MARINE...JLB


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.