Area Forecast Discussion
Issued by NWS Marquette, MI

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000
FXUS63 KMQT 181930
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
330 PM EDT THU SEP 18 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 506 AM EDT THU SEP 18 2014

WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL TROUGH FROM
NRN QUEBEC INTO THE ERN CONUS AND A RIDGE OVER THE ROCKIES RESULTING
IN NW FLOW THROUGH THE NRN GREAT LAKES. AT THE SFC...HIGH PRES WAS
CENTERED OVER NRN ONTARIO BRINGING LIGHT ENE ACROSS LAKE SUPERIOR
AND UPPER MI. THE SHALLOW INTRUSION OF COLD AIR BEHIND A COLD FRONT
INTO SRN WI HAS SHARPENED A 925 MB INVERSION AND TRAPPED ENOUGH LOW
LEVEL MOISTURE TO MAINTAIN EXTENSIVE CLOUD COVER ACROSS UPPER MI AND
NRN WI. IN ADDITION...MOISTENING FROM THE FLOW ACROSS LAKE
SUPERIOR... WITH SOME BANDING EVIDENT...HAS ALSO HELPED TO REINFORCE
THE CLOUDS. AS A RESULT...TEMPS ARE NOT EXPECTED TO DROP OFF ENOUGH
TO PRODUCE FROST OR FREEZING CONDITIONS.

TODAY...AS THE HIGH BUILDS TO THE SE AND WINDS VEER TO THE EAST
DAYTIME HEATING/MIXING WILL HELP ERODE THE LOW CLOUDS AND BRING
CLEARING BY THIS AFTERNOON. WITH 925 MB TEMPS REBOUNDING TO AROUND
6C...EXPECT MAX READINGS IN THE MID 50S EAST AND THE UPPER 50S SOUTH
AND WEST.

TONIGHT...SRLY FLOW WILL INCREASE FROM THE UPPER MS VALLEY TOWARD
THE WRN GREAT LAKES AS THE HIGH SHIFTS TO THE EAST AND LOW PRES
DEVELOPS FROM MANITOBA INTO THE PLAINS. ALTHOUGH THE STRONGER
MOISTURE INFLOW...ISENTROPIC LIFT AND RESULTING PCPN WILL REMAIN NW
OF THE CWA...MID/HIGH CLOUDS ARE EXPECTED TO INCREASE OVERNIGHT FROM
WEST TO EAST. TEMPERATURES WILL ALSO REMAIN STEADY OR SLOWLY RISE
LATE. HOWEVER...THERE STILL MAY BE SOME PATCHY FROST OVER THE EAST.

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 329 PM EDT THU SEP 18 2014

UPPER LEVEL PATTERN TRANSITIONS FROM NORTHWEST FLOW ON BACK SIDE OF
TROUGHING OVER EASTERN CANADA TO MORE ZONAL FLOW BY THIS WEEKEND.
MAIN REASON THIS OCCURS IS 125+ KT H25 JET STREAK PLOWING ACROSS
PACIFIC TOWARD BRITISH COLUMBIA AND PACIFIC NORTHWEST. AS THIS JET
ENERGY REACHES NORTHERN PLAINS ON FRIDAY IT WILL HELP DEVELOP TROUGH
ALOFT OVER NORTHERN ONTARIO AND THE LK SUPERIOR REGION. INITIAL WAVE
ON LEADING EDGE OF THIS TROUGH WORKS THROUGH FRIDAY NIGHT INTO
SATURDAY MORNING AND THIS SHOULD BE WHEN MAJORITY OF RAIN OCCURS.
AT THE SFC...A TROUGH WITH A WIND SHIFT AND LOW-LEVEL DRYING WILL
MOVE THROUGH. ANOTHER SHORTWAVE IS FORECAST TO SWING THROUGH
SATURDAY NIGHT INTO SUNDAY MORNING. A STRONGER SFC COLD FRONT
WILL ACCOMPANY THAT SHORTWAVE. WARMER THAN NORMAL TEMPS FRIDAY NIGHT
INTO SATURDAY...BEFORE TEMPERATURES FALL BACK BELOW NORMAL ON SUNDAY.
LOW TEMPS ON FRIDAY NIGHT MAY NOT FALL BLO 60 DEGREES IN SOME AREAS
AS THE WARM SOUTH/SOUTHWEST WINDS PERSIST. THOUGH THERE COULD BE LOW
CLOUDS AROUND TO START THE DAY ON SATURDAY...APPEARS THERE WILL BE
ENOUGH MIXING BY LATE MORNING/EARLY AFTN TO RESULT IN MIXING HEIGHTS
BUILDING TO AT LEAST TO H9/H875 WITH HIGHS POTENTIALLY WELL INTO THE
70S IF THERE IS AT LEAST PARTIAL SUNSHINE. MUCH DIFFERENT STORY ON
SUNDAY WITH HIGHS NEAR LK SUPERIOR BARELY REACHING ABOVE 50 DEGREES
AND ONLY INTO THE 50S FARTHER INLAND AND OVER SOUTHERN CWA AND NEAR
LK MICHIGAN. NOTHING TOO HIGH IMPACT IN TERMS OF NORTH TO NORTHWEST
WINDS IN WAKE OF THE COLD FRONT ON SUNDAY...WITH 20-30 MPH ON LK
SUPERIOR AND NEAR THE SHORE...NOTHING TOO ATYPICAL FOR SEPTEMBER.

BACK TO THE IMPACTS TIED TO SYSTEM MOVING THROUGH FRIDAY NIGHT
THROUGH SATURDAY. DOES NOT APPEAR THAT HEAVY RAIN WILL BE A LARGE
THREAT WITH THIS SYSTEM...MAINLY BECAUSE THE GREATEST SURGE OF H85
THETA-E ADVECTION AND PWATS NEAR 200 PCT OF NORMAL ONLY OCCURS FOR
BRIEF PERIOD ON FRIDAY NIGHT BEFORE THE H85 JET VEERS MORE WEST BY
12Z SATURDAY. SOUTH WINDS AHEAD THE INITIAL LOW PRESSURE SYSTEM AND
SFC TROUGH WILL BE STRONG AND GUSTY FRIDAY EVENING. SOUNDINGS SHOW
STABLE PROFILE BLO AN INVERSION AT H9-H85...BUT BLYR WINDS ARE STILL
IN THE 40-50 MPH RANGE. PRESSURE FALLS OVER EASTERN LK SUPERIOR TO
JAMES BAY WILL ENHANCE THE SOUTH WINDS. OVERALL...COULD SEE SOUTH
WINDS GUSTING OVER 35 MPH VCNTY OF EASTERN LK SUPERIOR AND NORTHERN
LK MICHIGAN WITH SOME GUSTS 30-35 MPH ON THE LAND AREAS OF THE
EASTERN CWA. ATTM THINK THE WIND GUSTS SHOULD STAY BELOW ADVY
CRITERIA OF 45 MPH.

ADDITIONAL IMPACT COULD BE STRONG OR POSSIBLE SEVERE STORMS ON
SATURDAY AFTN AS SFC TROUGH CROSSES THE AREA ALONG WITH SHORTWAVE
AND PUSH OF MID-LEVEL MOISTURE. MLCAPES UP OVER 1500J/KG AND WITH
THE UPPER TROUGH IN THE VCNTY...0-6KM SHEAR IS OVER 40 KTS. NAM
QUITE AGGRESSIVE DEPICTING BUILD UP OF INSTABILITY...WHILE THE GFS
AND ECMWF ARE NOT AS MUCH. SREF PROBABILITIES OF MUCAPE OVER
1000J/KG ALONG WITH SHEAR OVER 30 KTS SHOW SOME INCREASE 15-21Z
SATURDAY OVER MAINLY THE SCNTRL CWA...BUT STILL REMAIN MAINLY BLO 10
PCT. FREEZING LEVEL IS 9-11KFT AND HEIGHT THAT CORES ALOFT WOULD
HAVE TO REACH TO POSSIBLY PRODUCE SEVERE 1 INCH HAIL IS 27-30KFT...
SO LARGE HAIL IS A POSSIBILITY. LOW-LEVEL LAPSE RATES NOT THAT
STEEP...BUT WITH THE DRY AIR H9-H7 AND STRONG WINDS H7-H5...SUPPOSE
STRONG WIND GUSTS COULD MAKE IT TOO SFC. PRIMARY AREA HIGHLIGHTED IN
SPC DAY3 OUTLOOK IS FARTHER EAST AND SOUTH AHEAD OF COLD FRONT
WITHIN SW H85 JET AND WHERE THE SFC DWPNTS ARE WELL INTO THE 60S.
DOES SEEM IF TIMING WORKS OUT WHERE SOME INSTABILITY CAN BUILD OVER
CNTRL UPR MICHIGAN AHEAD OF THE SHORTWAVE...THERE IS ENOUGH OF A
RISK FOR SEVERE...SO WILL CONTINUE TO MENTION IN THE HWO.

INTO SATURDAY NIGHT...COULD STILL SEE SOME TSRA WITH COMBINATION OF
SHORTWAVE AND STEEP H7-H4 LAPSE RATES/COLD POCKET AT H5/. NO STRONG
STORMS EXPECTED THROUGH AS EFFECTIVE SHEAR DIMINISHES TO LESS THAN
20 KTS BY THIS TIME. BESIDES THE CHILL THAT WILL BE IN THE AIR ON
SUNDAY...ANOTHER SHORTWAVE DROPPING THROUGH IN NW FLOW ALOFT AND THE
H85-H5 THERMAL TROUGHING/EXTENSIVE MOISTURE WILL LIKELY BE ENOUGH TO
KICK OFF SOME SHOWERS OVER MAINLY INLAND AREAS. WATER TEMPS OVER
MUCH OF LK SUPERIOR ARE IN THE 6-8C RANGE BASED ON BUOYS AND SHIP
REPORTS. IMMEDIATE NSH AREAS OF SCNTRL LK SUPERIOR MAY BE OVER 10C
IN SOME SPOTS BUT THAT IS LOCALIZED. THEREFORE WITH H85 TEMPS STAYING
ABOVE 0C WILL NOT BE LOOKING AT MUCH LAKE ENHANCEMENT ESPECIALLY AS
LOW-LEVEL FLOW WILL BE TRENDING MORE ANTICYCLONIC THROUGH THE DAY
WITH SFC RIDGE EXPANDING EAST FM THE NORTHERN PLAINS.

EXTENDED...TROUGHING ALOFT DOMINATES EARLY NEXT WEEK. HINT OF
STRONGER SHORTWAVE AND RE-INFORCING SFC TROUGH DROPPING ACROSS
THE UPPER GREAT LAKES ON MONDAY. GFS FARTHER WEST WITH THE WAVE AND
WOULD INDICATE AT LEAST ISOLD SHRA ON MONDAY. ECMWF AND GEM-NH AND
PREVIOUS FORECASTS...KEEP BULK OF WAVE AND MOISTURE TOO FAR EAST TO
RESULT IN MUCH SHRA. SINCE GFS IS ALSO TRENDING THIS WAY WITH 12Z
RUN...WILL KEEP IT DRY ATTM. HIGH PRESSURE INITIALLY AT THE SFC THEN
ALOFT AS WELL BUILDS ACROSS REGION TUESDAY THROUGH THURSDAY. PWATS
LESS THAN 50 PCT OF NORMAL AND AFTN SFC DWPNTS IN THE 30S INDICATE
THERE COULD BE FROST TUESDAY NIGHT/WEDNESDAY NIGHT FOR ALL INLAND
AREAS AND MAYBE EVEN THURSDAY NIGHT FOR INLAND AREAS OF EASTERN CWA.
DAYTIME TEMPS WILL LIKELY BE AT OR ABOVE NORMAL...ESPECIALLY
WEDNESDAY INTO THURSDAY AS WARMER AIR WORKS IN ALOFT /H85 TEMPS OVER
10C/ WITH THE BUILDING UPPER RIDGE. SINCE IT LOOKS LIKE THERE WILL
BE LITTLE IN WAY OF CLOUD COVER EITHER DAY...TEMPS COULD EVEN REACH
THE 70S. NORMAL HIGHS FOR MID-LATE SEPTEMBER ARE IN THE MID TO UPPER
60S.
&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 146 PM EDT THU SEP 18 2014

LOW-LEVEL MOISTURE WRAPPING AROUND THE BACKSIDE OF HIGH PRESSURE
OVER THE REGION WILL CONTINUE WITH MVFR CIGS AT IWD...AND BRING MVFR
CIGS TO CMX AND SAW OVERNIGHT THROUGH MUCH OF FRIDAY. AN INCREASING
PRESSURE GRADIENT ACROSS THE REGION WILL ALLOW FOR GUSTY S TO SSW
WINDS AT ALL SITES BEGINNING FRIDAY MORNING...ESPECIALLY AT SAW.
EXPECT GUSTS AS HIGH AS 30KTS DURING THE AFTERNOON HOURS. AN
APPROACHING LOW-LEVEL TROUGH IS EXPECTED TO BRING -SHRA TO WESTERN
UPPER MI DURING THE AFTERNOON...BUT ANY PRECIP SHOULD HOLD OFF AT
IWD OR CMX UNTIL AFTER 18Z.
&&

.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 506 AM EDT THU SEP 18 2014

AS HIGH PRES OVER NRN ONTARIO SHIFTS TOWARD NEW ENGLAND TODAY INTO
TONIGHT...WINDS WILL VEER TO THE S AND THEN INCREASE THROUGH THE DAY
ON FRI AS THE PRES GRADIENT SHARPENS BETWEEN THE DEPARTING HIGH AND
A TROUGH MOVING THRU SCENTRAL CANADA/NORTHERN PLAINS. SSW WINDS
COULD REACH 30 KTS...BUT HIGHER STABILITY OVER THE COLD 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 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.
&&

$$

SHORT TERM...JLB
LONG TERM...JLA
AVIATION...KLUBER
MARINE...JLB







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