Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 162010
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
410 PM EDT TUE SEP 16 2014

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 409 PM EDT TUE SEP 16 2014

WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A RIDGE OVER WRN NAMERICA
AND A TROF OVER ERN NAMERICA. IN THE TROF...ONE SHORTWAVE IS MOVING
E OF JAMES BAY WITH SECOND JUST UPSTREAM IN FAR NRN ONTARIO. NW FLOW
ACROSS CNTRL CANADA IS SENDING THE NEXT SHORTWAVE SE INTO NRN
SASKATCHEWAN/NRN MANITOBA. AT THE SFC...COLD FRONT ASSOCIATED WITH
THE FIRST SHORTWAVE EXTENDS FROM SRN JAMES BAY TO JUST N OF LAKE
SUPERIOR TO FAR SRN MANITOBA. REGIONAL RADAR DISPLAY HAS SHOWN -SHRA
IN THE VCNTY OF THE COLD FRONT WITH PCPN AS FAR S AS NRN LAKE
SUPERIOR. PCPN HAS BEEN WEAKENING/DISSIPATING OVER THE LAST FEW HRS.
OVER UPPER MI...MOSTLY SUNNY SKIES HAVE ALLOWED TEMPS TO RISE TO 60
TO 70 THIS AFTN.

WHILE COLD FRONT TO THE N WILL CONTINUE TO DRIFT S AND THEN STALL
TONIGHT...IT WILL BE THE THIRD IN THE AFORMENTIONED TRIO OF
SHORTWAVES THAT WILL HELP PROPEL IT S THRU THE AREA ON WED. IN
RESPONSE TO THAT THIRD SHORTWAVE AND UNDER THE RIGHT ENTRANCE OF
UPPER JET OVER NRN ONTARIO/QUEBEC...A SUBTLE SFC WAVE IS ALSO
EXPECTED TO DEVELOP ALONG THE COLD FRONT AND TRACK ACROSS SOUTHERN
LAKE SUPERIOR OR UPPER MI VERY LATE TONIGHT THRU WED MORNING. A NICE
CORRESPONDING RIBBON OF LOW-LEVEL FRONTOGENESIS ALSO DEVELOPS.
SO...MODELS LOOK ON TRACK IN GENERATING A BAND OF -SHRA N OF COLD
FRONT AND PATH OF WEAK SFC WAVE TONIGHT/WED. UTILIZED A CONSENSUS OF
MODEL GUIDANCE IN PARTICULAR HIGHER RES MODELS TO CONSTRUCT PCPN
FCST FOR TONIGHT/WED IN ORDER TO MINIMIZE SLIGHT DIFFERENCES NOTED
IN COLD FRONT WHICH AFFECTS PCPN PLACEMENT. BASED ON LOCATION OF THE
STREAK OF FRONTOGENESIS...EXPECT MOST OF THE -SHRA TO PASS JUST N
AND E OF UPPER MI VERY LATE TONIGHT AND WED MORNING. SO...CHC POPS
WERE PAINTED ACROSS THE KEWEENAW AND ERN FCST AREA. OTHERWISE...
NOTHING MORE THAN SCHC POPS WERE USED.

TEMPS WED ARE TRICKY AS THERE WILL BE AN OPPORTUNITY FOR SOME
WARMING BEFORE FROPA. ACROSS THE N...FRONT SHOULD PASS EARLY ENOUGH
TO LIMIT MUCH WARMING. HIGHS OVER THE N SHOULD RANGE FROM THE UPPER
40S ACROSS THE TIP OF THE KEWEENAW TO MID 50S ELSEWHERE. AFTER
FROPA...TEMPS ACROSS THE N WILL LIKELY FALL INTO THE 40S IN THE
AFTN UNDER A BRISK NRLY WIND AND STRATUS DECK FOLLOWING FROPA.
ACROSS THE S...NUDGED HIGH TEMPS UP...TO AS HIGH AS THE UPPER 60S
FAR SCNTRL.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 333 PM EDT TUE SEP 16 2014

HIGH PRESSURE CURRENTLY OVER THE NORTHWEST TERRITORIES WILL DROP
SOUTHEAST AND OVER EASTERN LAKE SUPERIOR WEDNESDAY NIGHT BEHIND A
COLD FRONT THAT SLIDES ACROSS THE AREA WEDNESDAY. DRY AIR SURGING
IN BEHIND THIS FRONT SHOULD LEAD TO SKIES CLEARING ACROSS THE AREA
AROUND SUNSET AND SET THE U.P. UP FOR ANOTHER COLD NIGHT WITH
INLAND FROST. AS THE PREVIOUS SHIFT MENTIONED...THE FRONT SAGS A
LITTLE FARTHER SOUTH THAN SHOWN 24HRS AGO...WHICH WILL ALLOW MUCH OF
THE INTERIOR U.P. TO EXPERIENCE CLEAR SKIES. WITH PRECIPITABLE WATER
VALUES AROUND 30 PERCENT OF NORMAL AND GENERALLY LIGHT EASTERLY
FLOW...WILL CONTINUE TO HIGHLIGHT LOWS AROUND FREEZING OVER THE
INTERIOR (COLDEST EAST CLOSER TO THE HIGH CENTER). WITH THOSE LOW
TEMP VALUES...WILL CONTINUE TO SHOW AREAS OF FROST OVER MUCH OF THE
ARE AND MAY NEED FREEZE WARNINGS FOR SOME OF THE EASTERN AREAS.

DRY AIR WILL REMAIN IN PLACE FOR THURSDAY AS THE HIGH SHIFTS TO THE
EAST TOWARDS THE NEW ENGLAND STATES. EXPECT A MOSTLY SUNNY SKY OVER
THE AREA...ALTHOUGH SOME CLOUDS COULD IMPINGE ON THE SOUTHWEST CWA
WITH THE INCREASING SOUTH-SOUTHWESTERLY FLOW IN THE AFTERNOON.
HIGHS WILL REMAIN BELOW NORMAL AND IN THE 50S.

BEST CHANCES FOR PRECIPITATION DURING THE LONG TERM PERIOD WILL
COME FRIDAY THROUGH SATURDAY AS A SERIES OF SHORTWAVES DIVE ACROSS
THE AREA AND PUSH AN ASSOCIATED SURFACE TROUGH FROM THE CANADIAN
PRAIRIES AND CENTRAL U.S. EAST THROUGH THE GREAT LAKES REGION ON
SATURDAY. MODELS STILL DIFFERING ON SOME DETAILS (TO BE EXPECTED
WITH THE PHASING OF THREE WAVES JUST BEFORE REACHING THE
AREA)...BUT THE GENERAL IDEA OF BROAD WARM AIR ADVECTION
PRECIPITATION PUSHING EAST ACROSS THE AREA ON FRIDAY (ALONG WITH
BREEZY SOUTHERLY WINDS) AHEAD OF THE SURFACE TROUGH THAT WILL STALL
OVER THE AREA FRIDAY NIGHT AND SATURDAY MORNING BEFORE A MUCH
STRONGER SHORTWAVE DEVELOPS A SURFACE LOW IN THE DAKOTAS AND PUSHES
IT EAST ACROSS THE UPPER GREAT LAKES SATURDAY NIGHT INTO SUNDAY.
ALTHOUGH THE 12Z GEM DOESN/T AGREE WITH THIS IDEA...FEEL THAT IT IS
THE WAY TO TREND THE FORECAST SINCE THE 12Z GFS TRENDED TOWARDS THE
00Z ECMWF AND THE CONSISTENT IDEA IN THE ECMWF ENSEMBLE MEMBERS.
LATE ARRIVING 12Z ECMWF HAS SPED UP THE SYSTEM...WHICH LARGELY
AFFECTS THE SECOND HALF OF THE WEEKEND. WILL CONTINUE TO SHOW HIGH
END CHANCE AND LOW END LIKELY POPS (SHOWERS/THUNDERSTORMS) FOR THIS
PERIOD...ALTHOUGH THERE WILL LIKELY BE A BRIEF REPRIEVE LATE
SATURDAY NIGHT INTO SUNDAY MORNING BEHIND THE COLD FRONT THAT MOVES
THROUGH. THEN...AS COLDER AIR WRAPS SOUTH BEHIND THE LOW SUNDAY INTO
SUNDAY NIGHT...EXPECT ANOTHER PERIOD OF RAIN SHOWERS AND PROBABLY
SOME BREEZY WEST-NORTHWEST WINDS. DETERMINISTIC MODELS AND THEIR
ENSEMBLE MEMBERS CONTINUE TO TREND COOLER WITH 850MB TEMPS ON SUNDAY
INTO SUDNAY NIGHT (ANYWHERE FROM -1C TO 4C)...BUT WITH THE
WESTERN/CENTRAL LAKE SUPERIOR BUOYS ONLY SHOWING WATER TEMPS IN THE
MID 40S (AROUND 7-8C)...NOT SURE THE DELTA-T VALUE WILL BE COLD
ENOUGH FOR ENHANCEMENT. HIGH PRESSURE WILL BUILD IN BEHIND THE LOW
FOR MONDAY AND TUESDAY...LEADING TO MOSTLY CLEAR SKIES AND A TREND
BACK TOWARDS MORE NORMAL TEMPERATURES FOR LATE SEPTEMBER.
&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 118 PM EDT TUE SEP 16 2014

VFR CONDITIONS WILL PREVAIL AT KIWD/KCMX/KSAW THRU TONIGHT AS
LOW LEVELS REMAIN DRY. COLD FRONT CURRENTLY OVER NRN ONTARIO WILL
DROP S INTO PORTIONS OF NRN UPPER MI TONIGHT BEFORE STALLING AS
SUBTLE SFC LOW PRES DEVELOPS AND TRACKS ESE ALONG FRONT TOWARD THE
UPPER GREAT LAKES. IT IS EXPECTED THAT LOW CLOUDS AND BAND OF RAIN
THAT WILL DEVELOP N OF FRONT WILL PASS JUST N OF KCMX LATE TONIGHT.
AS THE VERY WEAK SFC LOW PASSES WED MORNING...COLD FRONT WILL PUSH
S...BRINGING LOW MVFR CIGS TO ALL TERMINALS. IFR NOT OUT OF THE
QUESTION AT KCMX AND ESPECIALLY KSAW WHICH WILL SEE A MORE DIRECT
UPSLOPE WIND AFTER FROPA.
&&

.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 409 PM EDT TUE SEP 16 2014

AHEAD OF AN APPROACHING COLD FRONT FROM THE N...SW WINDS AS HIGH AS
15-25KT THIS EVENING WILL FALL BACK TO GENERALLY 10-20KT TONIGHT AS
THE FRONT STALLS OVER THE AREA. FRONT WILL GET A PUSH S ON WED...AND
NE WINDS BEHIND THE FRONT WILL INCREASE TO 15-25KT FOR AT LEAST A
TIME. OVER FAR WRN LAKE SUPERIOR...COASTAL CONVERGENCE/FUNNELING
WILL PROBABLY RESULT IN WINDS AS HIGH AS 30KT LOCALLY. WINDS WILL
THEN DIMINISH TO UNDER 20KT WED NIGHT/THU AS HIGH PRES SETTLES OVER
NRN ONTARIO IN THE VCNTY OF LAKE SUPERIOR. AS THE HIGH THEN SHIFTS
TOWARD NEW ENGLAND AND A LOW PRES TROF APPROACHES FROM THE W...S
WINDS WILL INCREASE THU NIGHT/FRI. WITH S WINDS A MORE FAVORABLE
DIRECTION FOR STRONGER WINDS OVER ERN LAKE SUPERIOR THAN OVER THE
W...WINDS SHOULD REACH 20-30KT OVER THE ERN LAKE ON FRI. ALTHOUGH
WINDS WILL DIMINISH ON SAT AS THE TROF ARRIVES OVER THE UPPER
LAKES...W TO NW WINDS WILL AGAIN INCREASE TO AS HIGH AS 20-30KT
BEHIND THE TROF SAT NIGHT/SUN.
&&

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

$$

SHORT TERM...ROLFSON
LONG TERM...SRF
AVIATION...ROLFSON
MARINE...ROLFSON





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