Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 010857
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
457 AM EDT TUE SEP 1 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 414 AM EDT TUE SEP 1 2015

MUCH OF THE FOCUS ON THE SHORT TERM WILL BE WITH THE WEAK SURFACE
TROUGH DECAYING AS IT MOVES EAST ACROSS THE AREA TODAY AND TONIGHT
AND THE POTENTIAL FOR A FEW SHOWERS/THUNDERSTORMS ALONG IT. WATER
VAPOR IMAGERY AND RAP ANALYSIS SHOW THE UPPER RIDGE AXIS IS SHIFTING
EAST ACROSS LAKE HURON EARLY THIS MORNING...WHICH IS ALLOWING A
PLUME OF MOISTURE STRETCHING FROM NORTHWEST MEXICO TO JAMES BAY TO
SLOWLY MOVE EAST TOWARDS THE AREA. DID SEE A FEW SHOWERS ALONG THE
SURFACE TROUGH AND MOISTURE PLUME EARLIER IN THE NIGHT IN NORTHERN
MINNESOTA BUT THEY HAVE SINCE DISSIPATED. OUT AHEAD OF THE
TROUGH...THE COMBINATION OF VERY RADIATIONAL COOLING AND
SOUTHWESTERLY WINDS PULLING MOIST AIR ACROSS LAKE MICHIGAN HAS
PRODUCED FOG ONCE AGAIN OVER EASTERN UPPER MICHIGAN. THE LOWEST
VISIBILITIES HAVE BEEN RIGHT ALONG THE LAKE MICHIGAN
SHORELINE...WITH VISIBILITIES AT 1/4MI AT TIMES. DID ISSUE A MARINE
DENSE FOG ADVISORY EARLIER IN THE NIGHT BASED OFF THE SATELLITE
COVERAGE OF THE FOG ON LAKE MICHIGAN AND THE VISIBILITY RAPIDLY
FALLING ONCE IT REACHED KISQ. THE REST OF THE AREA HAS SEEN MOSTLY
CLEAR SKIES AND AREAS WHERE THE WINDS HAVE DECOUPLED HAVE SEEN
PATCHY GROUND FOG. EXPECT THAT TO CONTINUE INTO THE FIRST PART OF
THE MORNING HOURS BEFORE LIFTING TO A BRIEF STRATUS DECK AND THEN
DISSIPATING. ON FINAL ITEM TO NOTE FOR THIS MORNING IS THE SCATTERED
BORDERLINE MVFR/VFR CLOUDS IN WESTERN WISCONSIN. THESE HAVE BEEN
SHIFTING TO THE NORTH THIS MORNING AND WILL AID SOME DIURNAL CLOUDS
OVER PORTIONS OF THE AREA TODAY.

PRECIPITATION POTENTIAL IS A LITTLE MORE UP IN THE AIR FOR TODAY AND
LARGELY TIED TO SEVERAL FEATURES COMING TOGETHER IN A NARROW
CORRIDOR THIS AFTERNOON. FIRST...THE MOISTURE PLUME TO THE WEST OF
THE AREA ON WATER VAPOR WILL SHIFT TO THE EAST AND ACROSS THE
WEST/CENTRAL CWA THIS AFTERNOON. WHILE IT LOOKS FAIRLY IMPRESSIVE ON
WV IMAGERY...IT APPEARS THAT THE MODELS ARE DOING FAIRLY WELL ON THE
VERY THIN POCKETS OF MOISTURE WITHIN THAT AREA. SECOND...SOME OF THE
MODELS HAVE HINTS OF A WEAK SHORTWAVE IN EASTERN SOUTH DAKOTA THAT
WILL LIFT TO THE NORTHEAST AND ONLY BRUSH THE WEST/CENTRAL U.P. THIS
AFTERNOON. WHILE MOST OF IT WILL STAY NORTHWEST OF THE LAND
CWA...THERE ARE SOME HINTS AT A SOUTHERN APPENDAGE TO THE SHORTWAVE
THAT MAY WORK WITH THE SURFACE TROUGH AND POCKETS OF MOISTURE AROUND
850MB TO DEVELOP SOME SHOWERS/THUNDERSTORMS THIS AFTERNOON. COARSE
MODELS ARE SHOWING LIMITED DEVELOPMENT...WHILE THE HIGHER RESOLUTION
MODELS (INCLUDING 14KM ECMWF) ARE SHOWING SOME ISOLATED SHOWER
DEVELOPMENT BETWEEN 19-22Z OVER WEST-CENTRAL UPPER MICHIGAN
(GENERALLY FROM KIWD THROUGH BARAGA COUNTY AND INTO NORTHERN
MARQUETTE COUNTY). NCAR WRF ENSEMBLES FOCUS ON THAT AREA TOO FOR
INITIAL DEVELOPMENT BUT THEN EXPAND IT EAST-SOUTHEAST INTO THE
CENTRAL U.P. THIS EVENING (MARQUETTE/ALGER/DELTA AND NRN MENOMINEE).
HAVE KEPT THE POPS CONFINED TO THE AREA IMMEDIATELY AHEAD OF THE
WEAK TROUGH AND OVER THE LAND AREAS OF WEST/CENTRAL UPPER MICHIGAN.
WILL CONTINUE TO SHOW SLIGHT CHANCES BASED OFF THE UNCERTAINTY OF
THE SHORTWAVE BEING CLOSE/STRONG ENOUGH TO HELP THE SHOWERS AND ALSO
THE MARGINAL MOISTURE...ALTHOUGH DID INCLUDE A FEW CHANCES FOR THE
SOUTHERN HOUGHTON AND BARAGA COUNTY AREA DUE TO THE CONSISTENCY IN
THE MODELS ON SOMETHING OCCURRING IN THAT AREA. IN ADDITION...THERE
ARE INDICATIONS OF A VERY NARROW CORRIDOR OF STRONGER 0-6KM BULK
SHEAR (30-35KTS) OVER NORTH CENTRAL UPPER MICHIGAN ALTHOUGH MOST
AREAS WILL BE IN THE 20-25KT RANGE. COMBINING THAT WITH MLCAPE
VALUES OF 1-2K J/KG THIS AFTERNOON...THERE IS THE POTENTIAL FOR A
STRONGER STORM IF ALL OF THE PIECES COME TOGETHER.

THE TROUGH WILL CONTINUE SOUTHEAST AND WEAKEN THROUGH THE NIGHT
TONIGHT...LEADING TO A SUBTLE WIND SHIFT TO THE WEST-NORTHWEST.
SHOWERS SHOULD DISSIPATE THROUGH THE EVENING HOURS OVER THE
NORTHEASTERN PART OF THE CWA AND LEAD TO A PARTLY CLOUDY TO MOSTLY
CLEAR NIGHT. WILL HAVE TO WATCH FOR FOG DEVELOPMENT AGAIN
TONIGHT...ALTHOUGH THE MODELS ARE SHOWING SLIGHTLY DRIER LOW LEVEL
AIR. HAVE INCLUDED PATCHY TO AREAS OF FOG FOR NOW AND A LOT WILL
DEPEND ON THE DRYING BEHIND THE WEAK TROUGH.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 456 AM EDT TUE SEP 1 2015

UPPER LEVEL RIDGE TO START ON WEDNESDAY FM SOUTHWEST CONUS TO THE
NORTHEAST CONUS ALLOWS FOR POSSIBLE AFTN/EVENING SHRA/TSRA WED AND
THU. EXPECT THE RIDGE TO BUILD BACK FM SOUTHERN PLAINS TO THE UPPER
GREAT LAKES/NORTHERN ONTARIO BY LATE THIS WEEK IN RESPONSE TO STRONG
UPPER TROUGH DIGGING FM WESTERN CANADA DOWN THE WESTERN CONUS COAST.
TROUGH WILL CONTINUE DIGGING SOUTH...POSSIBLY AS FAR AS CALIFORNIA
BY THIS WEEKEND WHILE RIDGE EXPANDS OVER REST OF GREAT LAKES AND
NORTHEAST CONUS. AT THE SFC...SLOW MOVING COLD FRONT WILL BE STUCK
OVER THE PLAINS IN BETWEEN THE UPPER TROUGH AND UPPER RIDGE. SINCE
UPPER PATTERN CHANGES LITTLE THIS WEEKEND AND FRONT WILL BE PARALLEL
TO FLOW ALOFT...FRONT WILL STRUGGLE EASTWARD SATURDAY INTO SUNDAY.

SHORTWAVE CURRENTLY OVER CO/NEB/KS INTERSECTION IS FORECAST TO LIFT
NORTHEAST TO UPPER MISSISSIPPI RIVER VALLEY BY 12Z WED AND THEN TO
MOVE OVER WI/UPR MICHIGAN WED AFTN INTO WED NIGHT. MLCAPES FOCUSED
MORE FM DAKOTAS/NORTHERN MN ESE ACROSS WI AND LOWER MICHIGAN. MEAN
LAYER WINDS WNW-W...SO PREFER THE ECMWF/NAM/GEM-REGIONAL SHOWING
MAJORITY OF QPF OVER NORTHERN WI WITH THE SHRA/TSRA. ALSO NORTHERLY
GRADIENT/LAKE BREEZE ENHANCED WINDS OFF LK SUPERIOR WILL STABILIZE
LOW-LEVELS CLOSER TO LK SUPERIOR AND OVER EASTERN CWA. CHANCE POPS
HIGHEST TOWARD WI BORDER. FOR TEMPS...STUCK TOWARD PREVIOUS FORECAST
WITH MID 80S INLAND WEST HALF. COOLER MID-UPR 70S NEAR LK SUPERIOR
WITH ONSHORE WINDS. IF THOSE ONSHORE WINDS START UP QUICKER...COULD
SEE READINGS ENDING UP COOLER THAN FORECAST CURRENTLY SHOWS. KEPT
LINGERING POPS MAINLY SCNTRL AS THE SHORTWAVE DRIFTS ACROSS AND
SINCE SCNTRL WILL BE ON NORTHERN EDGE OF H85 CONVERGENCE ZONE AND
IN A POTENTIAL MID-LEVEL FGEN AREA WITH THE SHORTWAVE.

SUBSIDENCE INCREASES IN WAKE OF SHORTWAVE FOR FRIDAY...SO THINK IT
WILL BE MAINLY A DRY DAY. WINDS TURN BACK TO SSE-S WHICH RESULTS IN
BETTER CHANCE OF WARMING FOR ALL AREAS AWAY FM LK MICHIGAN. H85
TEMPS BUMP UP A COUPLE DEGREES AS WELL SO SHOULD SEE AT LEAST UPR
80S FOR WEST CWA ON FRIDAY AFTN. LOW-MID 80S ELSEWHERE...EXPECT UPR
70S NEAR LK MICHIGAN. NO CHANGE AT ALL THE HUMID CONDITIONS THAT
REALLY START UP TODAY...WITH DWPNTS SOLIDLY IN THE 60S. THOUGH NOT
IN THE FORECAST THE ENTIRE TIME...CANNOT RULE OUT FOG JUST ABOUT
ANYTIME WEDNESDAY THROUGH FRIDAY ESPECIALLY NEAR THE GREAT LAKES
SHORES WHERE THERE IS SOME ONSHORE WIND COMPONENT. HAVE SEEN THIS
LAST FEW DAYS AND NO REASON TO BELIEVE IT WILL NOT CONTINUE IN AT
LEAST SOME SHAPE OR FORM.

INTO THIS WEEKEND. EVENTUALLY...STRONGER SHORTWAVE TROUGH FORECAST
TO MOVE INTO WESTERN CANADA WILL ACT AS KICKER TO THE TROUGH OVER
THE NORTHWEST CONUS AND PUSH THE COLD FRONT TO THE EAST WHILE
DEVELOPING A SFC LOW ON ITS NORTHERN EDGE AT THE FOREFRONT OF THE
INITIAL UPPER LEVEL TROUGH. ENTIRE SYSTEM MOVES ACROSS UPPER GREAT
LAKES SUNDAY INTO MONDAY. ECMWF IN 3 OF ITS RUNS OVER LAST FEW DAYS
HAS HINTED THAT SHRA/TSRA MAY BREAK OUT WELL AHEAD OF MAIN FRONT
DOWNSTREAM OF SURGE OF 2000 J/KG MUCAPE FM NORTHERN PLAINS TO
NORTHWEST ONTARIO EITHER SATURDAY OR SUNDAY. 850-300MB THICKNESS
LINES WOULD SUPPORT THAT POTENTIAL SHOWING NW-SE FLOW SATURDAY AND W-
E FLOW ON SUNDAY. LATEST ECMWF NOW BUILDS UPPER RIDGE MORE AND HAS
H85 THETA-E RIDGE AS FAR NORTH AS SOUTHERN MANITOBA AND NORTHWEST
ONTARIO FRIDAY NIGHT INTO SATURDAY. IF THIS OCCURRS IT WOULD LIKELY
STAY DRY OVER UPR MICHIGAN FRIDAY NIGHT INTO SATURDAY AS SHORTWAVES
AND ASSOCIATED SHRA/TSRA WOULD STAY WELL TO THE NORTHWEST OF UPR
MICHIGAN/LK SUPERIOR. THEN...ONCE THE SHORTWAVE TROUGH OVER THE
NORTHWEST CONUS MOVES EASTWARD...THERE WOULD BE INCREASING CHANCES
OF SHRA/TSRA AS THE WEEKEND CONCLUDES AND ON INTO LABOR DAY. KEPT
POPS AT SLIGHT CHANCE OVER SOUTH AND EAST FRIDAY NIGHT INTO SATURDAY
NIGHT WITH CHANCE POPS OVER FAR NW CWA. BY SUNDAY...BROUGHT CHANCE
POPS OVER MORE OF THE NORTH CWA BUT STILL KEPT POPS SLIGHT CHANCE AT
BEST OVER SCNTRL FARTHER AWAY FM THE THETA-E RIDGE AND MORE INTO THE
LARGER SCALE RIDGE.

GFS BLOWS COLD FRONT THROUGH QUICKLY SUNDAY NIGHT INTO MONDAY WHILE
ECMWF IS SLOWER MAINLY DUE TO SHOWING MORE OF A CUTOFF UPPER LOW
OVER THE WESTERN CONUS SATURDAY NIGHT INTO SUNDAY. WILL CONTINUE TO
USE CONSENSUS POPS FOR FORECAST WHICH ARE HIGHEST FOR SUN NIGHT INTO
LABOR DAY. STILL LOOKS COOLER FOR SUNDAY AND LABOR DAY...AT LEAST
COMPARED TO WARMTH THIS WEEK. BASED ON TRENDS FM LATEST MODELS...
CONFIDENCE IS LESSENING IN A SIGNIFICANT COOL DOWN NEXT WEEK. STAY
TUNED.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 121 AM EDT TUE SEP 1 2015

EXPECT VFR CONDITIONS TO PREVAIL AT THE SITES THROUGH MUCH OF THE
REST OF THE PERIOD. KSAW AND CMX WILL SEE THE POTENTIAL FOR PATCHY
GROUND FOG LATE TONIGHT.
&&

.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 414 AM EDT TUE SEP 1 2015

SOUTHWESTERLY WINDS WILL WEAKEN THROUGH THE DAY TODAY AS A WEAK
SURFACE TROUGH SLOWLY DROPS SOUTHEAST ACROSS LAKE SUPERIOR TODAY
AND TONIGHT. THIS WILL LEAD TO WINDS FALLING BELOW 15KTS THIS
AFTERNOON AND REMAIN THAT WAY INTO THURSDAY AS A HIGH PRESSURE
RIDGE NOSES BACK NORTHWEST INTO THE UPPER GREAT LAKES REGION.
SOUTHERLY FLOW WILL STRENGTHEN FRIDAY INTO THE WEEKEND AHEAD OF A
BROAD LOW PRESSURE TROUGH STRETCHING FROM CENTRAL CANADA TO THE
CENTRAL PLAINS THAT WILL MOVE EAST INTO THE UPPER MISSISSIPPI
VALLEY. FINALLY...EXPECT PATCHY TO AREAS OF FOG TO OCCUR OVER LAKE
SUPERIOR INTO THURSDAY.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
  DENSE FOG ADVISORY UNTIL NOON EDT TODAY FOR LMZ248-250.

&&

$$

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


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