Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 011941
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
341 PM EDT WED JUL 1 2015

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 340 PM EDT WED JUL 1 2015

12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW A NW FLOW ALF INTO
THE GREAT LKS BTWN A TROF OVER ERN NAMERICA AND RDG OVER THE W. SFC
HI PRES RDG/DRY AND STABLE AIRMASS SHOWN ON THE 12Z INL RAOB
ASSOCIATED WITH SHRTWV RDG AXIS APRCHG FM THE NW IS BRINGING A
MOSUNNY DAY TO MOST OF UPR MI. THERE ARE SOME LINGERING CLDS OVER
THE ERN CWA ASSOCIATED WITH LLVL MSTR SHOWN ON THE 12Z APX RAOB...
BUT COMBINATION OF DAYTIME HEATING/DRY ADVCTN IS TENDING TO
DISSIPATE THE LINGERING CLDS. LOOKING UPSTREAM...THERE IS A SHRTWV
DIVING SEWD THRU MANITOBA INTO FAR NW ONTARIO. THERE IS QUITE A BIT
OF CLD COVER AND SOME SHOWERS IN ADVANCE OF THIS DISTURBANCE AS THE
DYNAMIC FORCING IS LIFTING A MORE MOIST ENVIRONMENT SHOWN ON THE 12Z
YPL RAOB.

MAIN FCST CONCERNS IN THE SHORT TERM INCLUDE LO TEMPS TNGT AND THEN
SHOWER CHCS ON THU ASSOCIATED WITH SHRTWV APRCHG FM THE NW.

TNGT...THE EVNG WL BE MOCLR WITH THE DRY HI PRES OVHD...BUT MODELS
SHOW INCRSG MID LVL MSTR IN ADVANCE OF APRCHG SHRTWV ARRIVING NW TO
SE TNGT. WITH LINGERING LLVL DRY AIR AND THE LARGE SCALE FORCING
REMAINING TO THE NW AND TENDING TO WEAKEN WITH TIME...SUSPECT ANY
ACCOMANYING SHOWERS WL BE CONFINED TO THE AREA NEAR ISLE ROYALE...
WHERE MODELS SHOW MORE VIBRANT H85 THETA E ADVECTION CLOSER TO THE
FADING DEEP LYR FORCING. EXPECT THE LOWEST MIN TEMPS OVER THE
INTERIOR E/SCENTRAL...WHERE THE CLDS WL ARRIVE LATEST AND SFC HI
PRES AXIS WL BE OVHD NEAR 12Z THU.

THU...SHRTWV RDG AXIS TRAILING THE WEAKENING SHRTWV IS FCST TO DROP
INTO THE UPR LKS. ALTHOUGH AXIS OF HIER MID LVL MSTR IS PROGGED TO
REMAIN...ABSENCE OF APPRECIABLE DYNAMIC FORCING ASSOCIATED WITH THE
INCOMING SHRTWV RDG WL LIMIT POPS TO THE FAR NW CWA CLOSER TO AXIS
OF HIER H85 THETA E AND WHERE ANOTHER SHRTWV/DEEP LYR QVECTOR CNVGC
WL APRCH LATE. DESPITE THE BKN CLDS...EXPECT MAX TEMPS TO REACH WELL
INTO THE 70S AWAY FM LK MODERATION WITH H85 TEMPS FCST TO REACH 13-
14C OVER THE W AT 00Z FRI.

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 340 PM EDT WED JUL 1 2015

EXTENDED PATTERN OVER THE UPPER GREAT LAKES REGION WILL BE
HIGHLIGHTED BY A NW FLOW SHORTWAVE TROUGH MOVING THROUGH LATE THU
NIGHT AND FRI...FOLLOWED BY A LONG WAVE RIDGE BUILDING IN FOR THE
4TH OF JULY WEEKEND...THEN ANOTHER STRONGER SHORTWAVE TROUGH AND
ASSOC COLD FROPA MOVING THROUGH LATE SUN NIGHT INTO MONDAY.

BEGINNING THU NIGHT AND FRI...MODELS SHOW NW FLOW SHORTWAVE DROPPING
SE FM MANITOBA AND NW ONTARIO INTO THE UPPER GREAT LAKES LATE THU
NIGHT INTO FRI. NOT EXPECTING WIDESPREAD PCPN FROM THIS SYSTEM AS
MODELS INDICATE BEST DEEP LAYER MOISTURE AND Q-VECT CONVERGENCE
ASSOC WITH THE SHORTWAVE STAYING NORTH AND EAST OF THE UPPER GREAT
LAKES AND ALSO WELL AHEAD OF ASSOC SFC TROUGH/FRONTAL BOUNDARY. MUCH
OF CONVECTION THAT FORMS WILL LIKELY BE TIED TO CONVERGENCE ALONG
PASSAGE OF TROUGH/FRONTAL BOUNDARY THAT MAY BE AIDED BY DEVELOPING
LAKE BREEZES FRI AFTERNOON INTO FRI EVENING. MODELS VARY GREATLY ON
FCST DIURNAL INSTABILITY AS ECMWF AND GEM-NH INDICATE MLCAPE OF A
FEW HUNDRED J/KG WHILE THE NAM SHOWS INLAND MLCAPES IN EXCESS OF
1500 J/KG AND THE GFS IS GENERALLY 500-1000 J/KG. WITHOUT REALLY A
GULF MOISTURE CONNECTION...SUSPECT NAM AND GFS SFC DEWPOINTS
REACHING INTO THE MID 60S ARE OVERDONE THUS LEADING TO INFLATED
INSTABILITY VALUES. GIVEN PATTERN...WOULD TEND TO TRUST LOWER GEM-NH
AND ECMWF VALUES MORE. NEVERTHELESS WITH GEM-NH AND ECMWF
SCENARIOS...COULD STILL SEE SOME ISOLD/SCT SHRA/TSRA DEVELOP WITH
CONVERGENCE ALONG FRONTAL BOUNDARY/LAKE BREEZES FRI AFTERNOON INTO
FRI EVENING ESEPCIALLY OVER CENTRAL UPPER MI. SO WILL CONTINUE TO
CARRY LOWER CHC POPS FOR THIS POSSIBILITY OVER THIS TIME FRAME.

FRI NIGHT INTO SUNDAY...AFTER ANY LINGERING FRI EVENING CONVECTION
ENDS WITH EXITING FRONTAL BOUNDARY...EXPECT GENERALLY DRY CONDITIONS
INTO THE HOLIDAY WEEKEND WITH CLOSER TO NEAR NORMAL TEMPS AS MODELS
INDICATE MID-UPPER LEVEL RIDGE BUILDING IN FM SCNTRL CANADA AND THE
NRN PLAINS. LAKE BREEZE CONVECTION ON SATURDAY WILL BE MININAL AND
CONFINED TO WI BORDER COUNTIES IF IT HAPPENS AT ALL AS MID-LVLS OFF
FCST SNDGS LOOK TOO DRY. NAM AND GFS MODELS GENERATING MODEST
INSTABILITY 500-1000 J/KG BUT THAT`S ONLY BECAUSE FCST DEWPOINTS ARE
IN THE LOWER TO MID 60S. AGAIN THESE DEWPOINTS LOOK TOO HIGH GIVEN
PATTERN WITH NO REAL SOUTHERLY FLOW OF MOISTURE INTO THE AREA.
SOUTHERLY FLOW DOES INCREASE SUNDAY AHEAD OF NEXT APPROACHING
SHORTWAVE/FRONTAL BOUNDARY WHICH MAY LEAD TO AN INCREASE IN
MOISTURE...BUT EXPECT MID-LVL RDGG AND LARGE SCALE ANTICYCLONIC FLOW
TO GENERALLY SUPPRESS CONVECTION AND KEEP CONDITIONS DRY ACROSS THE
AREA.

SUN NIGHT INTO MONDAY...APPROACH OF MORE PROMINENT SHORTWAVE AND
ASSOC COLD FROPA AS DEPICTED BY MODELS SHOULD LEAD TO A BETTER
CHANCE OF SHOWERS/THUNDERSTORMS LATE SUNDAY NIGHT INTO MONDAY
ESPECIALLY GIVEN FCST PWATS AROUND 1.75 INCHES OUT AHEAD OF THE
FRONTAL SYSTEM. WITH MODEL DIFFERENCES IN TIMING OF FRONTAL SYSTEM
WILL GENERALLY UTILIZE A CONSENSUS APPROACH FOR POP FCST. MOST OF
THE MODELS SUGGEST FRONTAL BOUNDARY EXITING EAST LATE MON EVENING OR
EARLY OVERNIGHT MON NIGHT SO EXPECT ANY LINGERING CONVECTION TO END
BY THIS TIME.

TUESDAY AND WEDNESDAY...DRIER CONDITIONS ARE EXPECTED AS SFC HIGH
PRES BUILDS IN FM THE PLAINS. SOME OF MODELS INDICATE PASSAGE OF
WEAK SHORTWAVES IN WNW FLOW BUT WITH LACK OF AVAILABLE MOISTURE NOT
EXPECTED ANY PCPN. TUESDAY COULD BE CHILLY WITH A NORTHERLY FLOW OFF
LAKE SUPERIOR AND PASSAGE OF 8H THERMAL TROUGH (WITH TEMPS 6-8C)
EXPECTED. WEDNESDAY/S TEMPS SHOULD REBOUND UNDER SUNNY SKIES AND
RETURN SSW FLOW ON BACKSIDE OF SFC RDG BUT MAY STILL BE SLIGHTLY BLO
NORMALS FOR THIS TIME OF THE YEAR.
&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 125 PM EDT WED JUL 1 2015

EXPECT VFR CONDITIONS THIS FCST PERIOD WITH DRY HI PRES DOMINATING.
THERE WL SCT-BKN MID CLDS AFTER THIS EVNG THRU THU AHEAD OF AN
APRCHG UPR DISTURBANCE...BUT THE LLVLS WL REMAIN TOO DRY FOR ANY
LOWER CIGS.
&&

.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 340 PM EDT WED JUL 1 2015

EXPECT LIGHT WINDS BELOW 20 KNOTS THROUGH THE FORECAST PERIOD WITH A
RELATIVELY WEAK PRES GRADIENT AND HI OVERWATER STABILITY TYPICAL FOR
EARLY SUMMER.
&&

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

$$

SHORT TERM...KC
LONG TERM...VOSS
AVIATION...KC
MARINE...KC



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