Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 180900
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
500 AM EDT THU SEP 18 2014

.UPDATE...
ISSUED AT 1032 PM EDT WED SEP 17 2014

UPDATED FORECAST TO INCLUDE KEWEENAW COUNTY IN FROST ADVY OVERNIGHT.
THE KEWEENAW PENINSULA HAS HAD CLEAR SKIES MOST OF THE EVENING. IN
FACT...THE KEWEENAW HAS REALLY BEEN THE ONLY AREA TO SEE MAINLY
CLEAR SKIES SO FAR TONIGHT. ALTHOUGH COPPER HARBOR IS THE ONLY AVBL
OB IN KEWEENAW COUNTY...OBSERVATIONS JUST ACROSS THE COUNTY LINE IN
NRN HOUGHTON COUNTY SHOW TEMPS ALREADY DOWN INTO THE MID 30S.
THUS...A FROST ADVY IS WARRANTED FOR KEWEENAW COUNTY OVERNIGHT.

ELSEWHERE...CLOUDS HAVE HELD TOUGH THIS EVENING...AND GIVEN ANOTHER
BATCH OF CLOUDS DROPPING SSW ACROSS THE LAKE...CLEARING WILL LIKELY
BE A SLOW PROCESS IN MANY AREAS DURING THE NIGHT. BASED ON SATELLITE
TRENDS...IT APPEARS CLEARING WILL REALLY GET UNDERWAY AFTER THIS
LAST AREA OF CLOUDS/LOW-LEVEL MOISTURE PASSES ACROSS THE AREA.
CLOUDS WILL PROBABLY END UP LINGERING LONGEST TO THE SW AND W OF
MARQUETTE AS THERE MAY BE A LITTLE LAKE COMPONENT TO THE CLOUD
COVER. IN THE END...EVEN IF THERE ARE ONLY 2-3 HRS OF MOSTLY CLEAR
SKIES...TEMPS SHOULD HAVE NO PROBLEM FALLING TO OR BLO FREEZING
INLAND FROM LAKE SUPERIOR...SO FROST/FREEZE HEADLINES APPEAR ON
TRACK.
&&

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 320 PM EDT WED SEP 17 2014

THE PASSAGE OF THE SAGGING COLD FRONT EARLY THIS AFTERNOON HAS
RESULTED IN LOW CLOUDS...SOME FOG...AND SIGNIFICANT COOLING ALONG
THE LAKE SUPERIOR SHORELINES. PLENTY OF CLEARING IS JUST UPSTREAM
OVER CENTRAL LAKE SUPERIOR...THANKS TO THE LARGE AREA OF HIGH
PRESSURE SET UP ACROSS MUCH OF MANITOBA. LOOK FOR THE SFC LOW TO
DRIFT SE ACROSS LAKE SUPERIOR OVERNIGHT.

PW VALUES AROUND 30 PERCENT OF NORMAL /0.2IN/ OVER LAKE WINNIPEG
THIS AFTERNOON WILL BE ABLE TO SLIDE ACROSS THE W HALF OF UPPER MI
OVERNIGHT. FEW CHANGES WERE MADE TO THE EXPECTED TEMPS
OVERNIGHT...BOTTOMING OUT IN THE UPPER 20S TO MID 30S...EXCEPT NEAR
40F ALONG THE GREAT LAKES SHORELINES. ONGOING FROST/FREEZE HEADLINES
STILL LOOK GOOD FOR ALL AREAS BUT KEWEENAW COUNTY. THERE IS A VERY
SMALL CHANCE FOR FOG THE TYPICAL LOCATION OF E GOGEBIC AND MUCH OF
IRON COUNTY OVERNIGHT WITH VIS FALLING TO MVFR CATEGORY. LOOKS LIKE
THIS COULD BE A POSSIBILITY...BUT WILL NOT INCLUDE IT AT THIS TIME
DUE TO THE LOWER PROBABILITY WITH THE SIGNIFICANTLY DRY AIR MOVING
IN AND LIMITED IMPACT IF IT WERE TO OCCUR.

LOOKING AHEAD INTO THURSDAY...THE SFC HIGH SLOWLY EXITING TO THE E
/ALONG THE ONTARIO AND QUEBEC BORDER BY 00Z FRIDAY/...WHILE THE
500MB RIDGE BUILDS IN ALOFT. LIGHT WINDS AROUND 10KTS OR LESS WILL
BE THE RULE. HOWEVER...DESPITE SOME WAA AT 850MB WITH 850MB TEMPS
RISING TO A CWA AVERAGED 5C...HIGH TEMPS IN THE 50S STILL LOOK
REASONABLE. THIS IS APPROX 10F BELOW THE SEASONAL AVERAGE FOR THIS
TIME OF YEAR.

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 459 AM EDT THU SEP 18 2014

MAIN FCST CONCERN FOCUSES ON CHCS FOR SHRA FRI THRU SUN AS A SERIES
OF SHRTWVS IN A W-NW FLOW MOVE ACROSS THE UPPER GREAT LAKES REGION.

MODELS COMING INTO BETTER AGREEMENT SHOWING THE FIRST IN A SERIES OF
SHORTWAVES MOVING INTO THE NRN PLAINS ON FRI. STRENGTHENING WAA AND
INCREASINGLY MOIST SW FLOW AHEAD OF THIS SHORTWAVE AND ITS ASSOC
TROUGH/FRONTAL BOUNDARY OVER THE NRN PLAINS WILL INCREASE PWAT
VALUES TO 1.5 INCHES OR HIGHER (MORE THAN 180 PCT OF NORMAL) OVER
THE FCST AREA BY FRI AFTERNOON. MODEL SNDGS INDICATE 500-1000 J/KG
OF MUCAPE AND SHOWALTER INDICES DROPPING AS LOW AS -2 TO -4C BY FRI
AFTERNOON/FRI NIGHT SO WOULD EXPECT AN INCREASING POTENTIAL FOR
ELEVATED TSRA AS THE WARM FRONT APPROACHES LATE IN THE DAY. MODEL
CONSENSUS SUGGESTS THE BEST CHC FOR SHOWERS WL BE OVER THE W HALF
OF THE CWA FRI AFTERNOON AND OVER THE E HALF FRI EVNG...WHEN
ISENTROPIC ASCENT/H925-7 MSTR TRANSPORT AND DEEP LAYER Q-VECT CONV
WL BE MAXIMIZED OVER THOSE AREAS. AS FOR TEMPS...INCREASING CLD COVER
WL HOLD DOWN SFC HI TEMPS INTO THE 60S ON FRI DESPITE INFLUX OF MUCH
WARMER AIR. EXPECT RELATIVELY SMALL TEMP FALL ON FRI NGT WITH STRONG
SW FLOW AND INFLUX OF HIGHER PWAT.

SAT...ANOTHER STRONGER SHRTWV APPROACHING FROM SCNTRL CANADA AND THE
NRN PLAINS WILL PROPEL THE SFC LOW PRES TROUGH AND ASSOC COLD FNT
THRU THE UPR LAKES. THERE MAY BE A BETTER CHANCE OF SHOWERS/TS
AGAIN SAT AFTERNOON MAINLY OVER CENTRAL AND ERN COUNTIES AS DYNAMICS
WITH SHORTWAVE LOOK TO BE IN SYNC WITH DAYTIME HEATING AND TIMING OF
COLD FRONTAL PASSAGE. MLCAPES FCST IN EXCESS OF 1000 J/KG WOULD
SUPPORT THUNDER AND WITH DEEP LAYER SHEAR VALUES OF 45-50 KTS A FEW
STRONG TO POSSIBLY SVR STORMS WOULD NOT BE OUT OF THE QUESTION IF
INSTABILITY IS REALIZED. WILL MENTION THIS POTENTIAL IN HWO.
DEPENDING ON HOW QUICKLY THE SFC COLD FNT PASSES ON SAT AND
POTENTIAL BREAKS IN CLOUD COVER...SOME PLACES MAINLY OVER THE CNTRL
CWA COULD SEE TEMPS RISE WELL INTO THE 70S AS H85 TEMPS ARE FCST TO
PEAK AS HI AS 16-17C.

SAT NGT INTO SUN...ALTHOUGH MODELS SHOW TIMING DIFFERENCES...THEY
SEEM TO BE IN AGREEMENT THAT ADDITIONAL SHRTWVS WILL BE DROPPING
INTO THE GREAT LKS THAT ARE FCST TO DEEPEN AN UPR TROF OVER THE
REGION. THE RESULTING NW CYCLONIC FLOW OVER THE AREA ALONG WITH THE
PASSAGE OF A SECONDARY COLD FRONT SHOULD YIELD A GOOD DEAL OF CLD
COVER...PERIODS OF SHOWERS AND COOLER WX AS H85 TEMPS DROP FM AS HI
AS 15C ON SAT AFTN TO AS LO AS 2-4C BY LATE SUN. IT APPEARS
UNLIKELY THAT H85 TEMPS WL FALL ENOUGH TO REALIZE MUCH OF A LK
ENHANCED COMPONENT TO THE CLDS/SHOWERS SUN AND SUN NGT WITH WSHFT TO
THE N GIVEN FAIRLY CHILLY LAKE SUPERIOR TEMPS OF 8-9C.

EXTENDED...WITH HI PRES AND MUCH DRIER AIR MOVING INTO THE GREAT LKS
EARLY NEXT WEEK...EXPECT DRY WX TO PREVAIL FROM MON THRU WED. MON IS
LIKELY TO BE RATHER COOL...BUT RETURN SW FLOW ON THE NW FLANK OF THE
HI SHIFTING TOWARD THE LOWER LKS WL BRING A WARMING TREND TUE THRU
WED.
&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 124 AM EDT THU SEP 18 2014

LOW-LEVEL MOISTURE/CLOUDS BEHIND COLD FRONT THAT PASSED YESTERDAY
WILL CONTINUE TO BE AN ISSUE OVERNIGHT AT KSAW. WITH SOME MOISTURE
OFF LAKE SUPERIOR AND NORTHERLY UPSLOPE FLOW...EXPECT LOW CLOUDS TO
PERSIST UNTIL LATE IN THE NIGHT WHEN WINDS VEER MORE EASTERLY OFF
LAND. VFR CONDITIONS WILL THEN BE THE RULE AT KSAW TODAY UNDER A DRY
AIR MASS. AT KCMX...VFR CONDITIONS SHOULD PREVAIL OVERNIGHT...THOUGH
OCNL MVFR CIGS ARE NOT OUT OF THE QUESTION GIVEN SOME CLOUD COVER
STILL OVER LAKE SUPERIOR. A PERIOD OF MVFR CIGS IS MORE LIKELY
TOWARD DAYBREAK AND THRU MID MORNING AS WINDS VEER MORE EASTERLY AND
UPSLOPE OFF THE WARMER WATER OF KEWEENAW BAY. VFR CONDITIONS WILL
THEN PREVAIL LATE MORNING THRU AFTN AT KCMX. AT KIWD...MVFR CIGS
WILL SCATTER OUT OVERNIGHT AS WINDS VEER TO A DOWNSLOPE E TO SE
DIRECTION. VFR CONDITIONS WILL THEN PREVAIL FOR THE REMAINDER OF THE
FCST PERIOD.
&&

.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 406 PM EDT WED SEP 17 2014

ENE WINDS ON THE SOUTHERN FLANK OF HI PRES MOVING SEWARD THRU NW
ONTARIO AS HI AS 20-25 KTS THIS EVENING WILL TEND TO DIMINISH
TONIGHT EXCEPT OVER THE FAR W...WHERE FUNNELING OF THE FLOW MIGHT
MAINTAIN STRONGER WINDS UP TO 20 KTS. AS THE HI SHIFTS TOWARD NEW
ENGLAND TOMORROW...THE WINDS WL VEER TO THE S AND THEN INCREASE THRU
THE DAY ON FRI AS THE PRES GRADIENT SHARPENS BETWEEN THE DEPARTING
HI AND A COLD FRONT MOVING THRU SCENTRAL CANADA/NORTHERN PLAINS. SSW
WINDS COULD REACH 30 KTS...BUT HI STABILITY OVER THE UNUSUALLY
CHILLY LAKE WATERS WILL LIMIT THE POTENTIAL FOR ANY GALES DESPITE
THE STRENGTH OF THE EXPECTED WINDS NOT FAR ABOVE THE WATER. WINDS
WILL THEN DIMINISH TO AROUND 20 KTS AND GRADUALLY VEER TO THE W-NW
FOLLOWING A COLD FRONTAL PASSAGE ON SAT BEFORE VEERING FURTHER TO
THE N AND INCREASING UP TO 25 KTS ON SUN/MON FOLLOWING THE PASSAGE
OF A REINFORCING COLD FRONT.
&&

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

$$

UPDATE...ROLFSON
SHORT TERM...KF
LONG TERM...VOSS
AVIATION...ROLFSON
MARINE...KC





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