Area Forecast Discussion
Issued by NWS Marquette, MI

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000
FXUS63 KMQT 271937
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
337 PM EDT SAT JUN 27 2015

.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 308 PM EDT SAT JUN 27 2015

PERSISTENT NW FLOW PATTERN ALOFT HAS BEEN AT LEAST TEMPORARILY
INTERRUPTED OVER PARTS OF GREAT LAKES AS STRONGER SHORTWAVE IS
SLIDING OVER THE LOWER GREAT LAKES ALONG WITH SFC LOW NEAR 1000 MB
OVER NORTHERN OHIO. OTHER THAN DAYTIME CUMULUS...HIGH PRESSURE
REMAINS IN CONTROL OVER UPR MICHIGAN. DOES APPEAR THAT POCKET OF
HIGHER MID-LEVEL MOISTURE ALONG WITH DAYTIME HEATING WAS ENOUGH TO
KICK OFF ISOLD SHRA ALONG LAKE BREEZE OVER THE KEWEENAW IN THE LAST
HOUR /ZONE EAST OF KCMX TO NORTHEAST OF TWIN LAKES/. NORTHWEST FLOW
IS PRESENT UPSTREAM OVER SCNTRL CANADA AND THAT IS CARRYING ALONG
VIGOROUS SHORTWAVE AND SFC TROUGH DIGGING ACROSS SOUTHERN MANITOBA
PER 12Z RAOBS AND WV LOOP AND ALSO SEEN FM THE HIGHER COVERAGE TO
SHRA/TSRA JUST AHEAD OF THE WAVE/SFC TROUGH. ISOLD SHRA/TSRA AHEAD
OF THAT WAVE ARE OCCURING AS FAR EAST AS NORTHEAST MINNESOTA TO JUST
NW OF THUNDER BAY ONTARIO.

SHORTWAVE OVER MANITOBA IS FORECAST TO DIG SSE AND STAY WEST OF UPR
MICHIGAN THROUGH SUNDAY AS SHOWN WELL BY TRACK OF H7-H5 Q-VECTOR
CONVERGENCE. SFC TROUGH INTENSIFIES INTO MORE OF A CLOSED SFC LOW
DIVING ACROSS MINNESOTA AND THIS KEEPS HIGHER SFC-H85 THETA-E
WRAPPED UP INTO THE LOW INSTEAD OF ADVECTING TO THE EAST OVER UPR
MICHIGAN. SEEMS THAT RAIN CHANCES EVEN LATE TONIGHT OVER THE WEST
ARE MINIMAL. WILL GO WITH BIAS CORRECTED MIN TEMPS TONIGHT WITH
LIGHT WINDS AND MAINLY CLEAR SKIES. A FEW INLAND LOCALES WILL DROP
INTO THE 40S CNTRL AND EAST.

PER WV LOOP AND H5 RAOBS...THERE IS LIKELY ANOTHER SHORTWAVE OVER
NORTHERN MANITOBA TO NORTH OF THE STRONGER WAVE...AND THAT SECONDARY
WAVE SHOULD TRACK MORE TOWARD LK SUPERIOR AND UPR MICHIGAN ON SUNDAY
AFTN...THUS INCREASING FORCING FOR ASCENT DURING PEAK HEATING. BASED
ON MODEL TRENDS...COULD BE DECENT AMOUNT OF SUNSHINE AHEAD OF THIS
WAVE AND SFC WIND FIELDS APPEAR MORE LAKE BREEZE DRIVEN THAN
ANYTHING ELSE WITH POSSIBLE INTERACTION OF WEAK TROUGH EXTENDING TO
NORTHEAST OF SFC LOW OVER SOUTHEAST MINNESOTA SUNDAY AFTN. AS LONG
AS MID CLOUDS DO STAY WEST...H85 TEMPS ARE UP TO 15C ON THE NAM/GEM-
REGIONAL OVER INTERIOR WEST AT 18Z SUNDAY...SUGGESTING TEMPS MAY
REACH MID 80S THERE AND UPPER 70S TO NEAR 80 AWAY FM ANY LOCALIZED
LAKE BREEZE. MOSTLY EXPECT LOW-MID 50S DWPNTS BUT SEEMS REASONABLE
THAT DWPNTS WILL POOL TOWARD UPR 50S TO AROUND 60 DEGREES ALONG LAKE
BREEZE OVER NORTHWEST CWA IN THE AFTN. NAM AND GEM-REGIONAL SHOW
THIS IDEA. RESULT WILL BE MLCAPES MAINLY IN THE 500-800J/KG RANGE
WITH POCKETS OF NEAR 1000J/KG. GIVEN THE LARGER SCALE LIFT AND LOW-
LEVEL CONVERGENCE ALONG WITH CONVECTIVE TEMPS IN THE MID
70S...EXPECT SHRA/TSRA TO DEVELOP AFTER NOON AND INCREASE IN
COVERAGE BY MID AFTN. COVERAGE SHOULD STAY SCATTERED AT BEST AS
AIRMASS STILL ON THE DRY SIDE.

NOT EXPECTING STRONG STORMS AS DEEP LAYER SHEAR IS VERY WEAK WITH
ONLY 10-20 KTS FORECAST. H85 DWPNTS BARELY REACH 10C IN THE
WEST...SO EVEN THOUGH STORM MOTION WILL BE SLOW...HEAVY RAIN SHOULD
NOT BE AN ISSUE EITHER.

.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 334 PM EDT SAT JUN 27 2015

MAIN FCST CONCERNS IN THE MEDIUM/EXTENDED RANGE WL FOCUS ON
POTENTIAL FOR/STRENGTH OF TS ON MON AND POPS AGAIN LATE IN THE
COMING WEEK TOWARD JULY 4TH. AN UPR TROF OVER THE E HALF OF NAMERICA
DOWNSTREAM OF A HI AMPLITUDE RDG OVER THE ROCKIES WL BE THE
DOMINATING WX PATTERN THRU MOST OF THIS FCST PERIOD. ALTHOUGH THERE
ARE HINTS THE PATTERN MAY DEAMPLIFY A BIT LATER NEXT WEEK...TEMPS
OVERALL SHOULD RUN AOB NORMAL THRU THIS FCST PERIOD.

SUN NGT...SHRTWV RESPONSIBLE FOR POPS OVER MAINLY WRN UPR MI ON SUN
IS FCST TO DIG SSEWD INTO IL DURING THE NGT...LEAVING A WEAK SFC RDG
AXIS ACROSS THE UPR LKS. BEST CHC FOR SOME POPS WL BE OVER THE W
EARLY AND AGAIN LATER AT NGT WITH ARRIVAL OF SOME DPVA/DEEP LYR
QVECTOR CNVGC/DEEPER MSTR IN ADVANCE OF NEXT SHRTWV DIGGING SSEWD
TOWARD THE UPR LKS. EXPECT THE LOWER MIN TEMPS OVER THE E...CLOSER
TO LINGERING DRIER AIR/PWAT UNDER AN INCH.

MON/MON NGT...APRCH OF SHRTWV EMBEDDED IN NW FLOW ALF/POCKET OF
LOWER H5 TEMPS ARND -14C/ATTENDANT SFC COLD FNT AS WELL AS DPVA/SOME
DEEP LYR QVECTOR CNVGC/AREA OF DEEPER MSTR WITH H85-5 MEAN RH UP TO
80 PCT WL BRING THE BEST CHC FOR SHOWERS/TS IN THE MEDIUM RANGE...
ESPECIALLY DURING PEAK HEATING ON MON AFTN/EVNG. MAIN LIMITING
FACTOR FOR MORE WDSPRD POPS WL BE LACK OF DEEP MSTR INFLOW THAT WL
BE DISRUPTED BY CIRCULATION ARND DEPARTING SHRTWV/SFC LO TO THE S.
LOOKS LIKE THE BEST CHC FOR HIER POPS WL BE OVER THE W HALF UNDER
AXIS OF HIER H85 THETA E ALREADY IN PLACE NEARBY AT 12Z MON. MODELS
VARY ON THE POTENTIAL FOR STRONGER STORMS. THE 12Z GFS REMAINS THE
MODEL THAT SHOWS THE GREATEST DESTABILIZATION...WITH MUCAPE AS HI AS
2000-2500 J/KG NEAR THE WI BORDER IN THE AFTN UNDER STEEPER MID LVL
LAPSE RATES AS HI AS 6.5-6.8C/KM AND HIER H85 DEWPTS NEAR 10C. THE
MORE CONSERVATIVE 00Z/12Z ECMWF SHOWS MUCAPE NO HIER THAN ABOUT 1000
J/KG NEAR THE WI BORDER. FAIRLY LO WBZ HGT FCST ARND 9K FT AND
POTENTIAL FOR SOME LK BREEZE INTERACTION WITHIN WEAK SFC GRADIENT
FLOW AHEAD OF THE INCOMING COLD FNT INDICATE THE POTENTIAL FOR SOME
LARGE HAIL UNDER THE STRONGER STORMS...ESPECIALLY IF THE HIER CAPE
VALUES ARE CORRECT. LIMITING FACTORS FOR STRONG/SEVERE TS WL BE
DEGREE OF DESTABILIZATION RELATED TO MORE WIDESPREAD CLD COVER AND
WEAKER SFC-6KM SHEAR IN THE 10-20 KT RANGE TO THE E OF RIBBON OF
STRONGER NW FLOW ALOFT FCST OVER MN. SOME OF THE SLOWER MODELS SHOW
SFC COLD FNT NOT PASSING UNTIL CLOSE TO 12Z TUE...SO SOME POPS WL
LINGER THRU MON NGT DESPITE LOSS OF DAYTIME HEATING AND FCST ARRIVAL
OF LARGER SCALE QVECTOR DVGC/SUBSIDENCE BY THE FASTER MODEL RUNS THAT
SHOW QUICKER PASSAGE OF STRONGER SHRTWV.

TUE...THERE COULD STILL BE SOME SHOWERS IN THE MRNG IF THE MODELS
SHOWING THE SLOWER COLD FROPA ARE CORRECT. THEN STEADY NNE WIND
BEHIND DEPARTING COLD FNT AND IN ADVANCE OF SFC HI PRES SINKING INTO
NW ONTARIO IS LIKELY TO BRING SOME LO CLDS/SPRINKLES/DRIZZLE TO
MAINLY THE HIER TERRAIN OF THE NRN TIER INTO THE AFTN BEFORE THE
CLOSER APRCH OF THE SFC HI/EVENTUAL ARRIVAL OF DRIER AIR/DAYTIME
HEATING CAUSE A RETURN OF AT LEAST PARTIAL SUNSHINE BY LATER IN THE
AFTN. EXPECT WELL BLO NORMAL MAX TEMPS NO HIER THAN THE 50S NEAR LK
SUP.

TUE NGT INTO THU...HI PRES WITH PWAT FCST AS LO AS 0.25 INCH WL
BRING A PERIOD OF DRY WX TO UPR MI. FCST H85 TEMPS IN THE 8-10C
RANGE WL ALLOW HI TEMPS IN THE 70 TO 75 RANGE AWAY FM LK MODERATION.
WITH LGT WINDS/MOCLR SKIES UNDER THE SFC HI PRES/DRY AIRMASS...MIN
TEMPS WL FALL WELL INTO THE 40S AND PERHAPS EVEN INTO THE 30S AT
SOME OF THE INTERIOR COLD SPOTS ON TUE AND WED NGTS.

THU NGT INTO JULY 4TH...MOST OF THE LONGER RANGE MODELS SHOW ANOTHER
SHRTWV APRCHG THE UPR LKS LATE IN THE COMING WEEK...WITH PCPN IN
ADVANCE OF THIS DISTURBANCE ARRIVING AS EARLY AS LATE THU. MODEL
CONSENSUS HINTS ATTENDANT COLD FROPA WL OCCUR LATE FRI OR FRI
NGT...WITH COOLER AND DRIER AIR ARRIVING ON SAT/JULY 4TH. BUT
AGREEMENT IS NOT UNIVERSAL...SO WL RELY ON MODEL CONSENSUS FOR NOW.
&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 137 PM EDT SAT JUN 27 2015

VFR CONDITIONS AND LIGHT WINDS WILL CONTINUE INTO SUNDAY MORNING.
ISOLATED SHOWERS OR THUNDERSTORMS MAY DEVELOP AT ALL TAF SITES ON
SUNDAY AFTERNOON DUE TO DAYTIME HEATING/INSTABILITY AND APPROACH OF
AN UPPER LEVEL DISTURBANCE. EVEN WITH A SHRA OR TSRA...CONDITIONS ARE
EXPECTED TO REMAIN VFR AT ALL TAF SITES.
&&

.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 308 PM EDT SAT JUN 27 2015

HIGH PRESSURE WILL LEAD TO WINDS STAYING LESS THAN 20KTS REST OF THE
WEEKEND. A SERIES OF WEAK TROUGHS WILL DROP SOUTHEAST ACROSS LAKE
SUPERIOR SUNDAY NIGHT THROUGH EARLY NEXT WEEK BUT WINDS ARE STILL
EXPECTED TO STAY BELOW 20KTS. HIGH PRESSURE BUILDS BACK OVER THE
UPPER GREAT LAKES BY MID WEEK. PATCHY FOG WILL DISSIPATE THROUGH
TONIGHT.
&&

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

$$

SHORT TERM...JLA
LONG TERM...KC
AVIATION...JLA
MARINE...JLA


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