116
FXUS63 KMQT 041946
AFDMQT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
345 PM EDT SUN JUN 21 2009
SYNOPSIS
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW LOWS OVER THE ST LAWRENCE
SEAWAY AND OVER NORTH CENTRAL ONTARIO. A BROAD RIDGE IS OVER
SOUTHWEST CANADA CAUSING A WEST NORTHWEST FLOW ACROSS THE NORTH
AMERICA. A RIDGE STRETCHES ACROSS THE EASTERN U.P. AND NORTHEAST
THROUGH EASTERN ONTARIO INTO JAMES BAY. A WEAK SHORTWAVE IS OVER
WEST CENTRAL ONTARIO...JUST NORTH OF THE MINNESOTA ARROWHEAD.
SURFACE ANALYSIS DEPICTS A COLD FRONT STRETCHING FROM A LOW OVER
NORTHERN MAINE NORTHWEST THROUGH NORTHERN LAKE SUPERIOR TO A LOW
OVER NORTHERN SASKATCHEWAN. ANOTHER FRONTAL SYSTEM STRETCHES LOW IS
OVER NORTHERN MISSOURI ACROSS THE SOUTHEASTERN STATES. A RIDGE IS
RUNS FROM A HIGH OVER SOUTHERN SASKATCHEWAN SOUTHEAST ACROSS THE
FORECAST AREA AND INTO SOUTHEAST ONTARIO.
SHORT TERM
THE MID LEVEL EASTERN CONUS LOW WILL RACE ACROSS NEW ENGLAND INTO
THE NORTHERN ATLANTIC TONIGHT...WHILE THE LOW OVER NORTHEASTERN
SASKATCHEWAN SLIDE DOWN THE LEE OF THE RIDGE AND INTO CENTRAL
ONTARIO. THIS LOW WILL PAUSE BRIEFLY OVER EASTERN ONTARIO AS IT
DEEPENS. SHORTWAVE ENERGY ACCOMPANYING THIS SYSTEM WILL SWEEP
THROUGH THE AREA TONIGHT. NAM TRIES TO BRING SHOWERS ISOLATED
SHOWERS TONIGHT...WHEREAS THE GFS KEEPING IT DRY. SINCE NAM HAS BEEN
ALSO CALLING FOR SHOWER TODAY WHERE THERE ISN'T ANY IN THE FORECAST
AREA...WILL FAVOR THE GFS. FORECAST SOUNDINGS SHOWING VERY DRY AT
THE LOW LEVELS...BELOW 5K FEET. THE INSTABILITY WITH THIS SYSTEM
WILL GENERATE SOME CUMULUS...BUT DO NOT EXPECT ANY OF THE RAINS TO
REACH THE GROUND. THE MAIN FORECAST CONCERNS WITH THIS PACKAGE
FOCUSES ON THE TEMPERATURES TONIGHT WITH THE DRY RIDGE LINGERING.
CLOUD COVER SHOULD HELP HOLD THE TEMPERATURES UP TONIGHT. SO WILL GO
WITH JUST A LITTLE UNDER THE GFS MOS.
THE SHORT WAVE TRACKING THROUGH LAKE SUPERIOR IS PROGGED TO SHARPEN
UPPER TROUGH OVER ONTARIO ON SUNDAY. COOLER AIR WILL SPILL INTO THE
UPPER GREAT LAKES. THE BOTH MODELS GENERATE A FEW SHOWERS OVER THE
SOUTHERN ZONE MAINLY IN THE AFTERNOON. ISENTROPIC ASCENT WITH THE
COLD FRONT TRACKING THROUGH THE AREA IN THE AFTERNOON AND THE
ADDITION OF A MOIST LEVEL AROUND 5K WILL KEEP SOME CLOUDS PRESENT SO
WILL LIMIT HEATING. CONDITIONS LOOK VERY DRY AT THE SURFACE...BUT
CAN NOT RULE OUT ISOLATED SHOWERS SO WILL CALL FOR SOME.
LONG TERM (SUN NIGHT THROUGH NEXT SATURDAY)
AS THE UPPER LOW OVER ONTARIO SHIFTS E-SE...SOME MINOR DIFFERENCES
OCCUR IN THE NAM AND GFS MONDAY INTO TUESDAY WHICH PLAY AN IMPORTANT
ROLE IN THE FCST. THE MODELS ARE IN SIMILAR AGREEMENT SUNDAY NIGHT
SHOWING POTENT SHORT WAVE ENERGY ROTATING INTO THE EASTERN HALF OF
THE FORECAST AREA. MID LEVEL LAPSE RATES WEAKEN OVERNIGHT WHICH
WOULD SUGGEST THAT SHOWER ACTIVITY WOULD BE LIMITED BUT WITH THE
BETTER MID LEVEL MOISTURE ACROSS THE EAST ASSOCIATED WITH THE UPPER
LOW AND THE MODEST MID LVL Q-VECTOR CONVERGENCE...HAVE OPTED TO KEEP
CHC POPS ACROSS THE EAST SUNDAY NIGHT. JUST TOO DRY OVER THE WEST
AND KEPT A DRY FCST. WILL BE ANOTHER CHILLY NIGHT WITH TEMPS ACROSS
MANY INLAND SPOTS IN THE MID-UPPER 40S.
AS THE UPPER LOW SLOWLY MOVES EAST ON MONDAY...ANOTHER UPPER
DISTURBANCE WILL DROP INTO THE UPPER LAKES. DESPITE COOL 500MB
TEMPS...MID LVL LAPSE RATES REMAIN QUITE WEAK...GENERALLY LESS THAN
5 C/KM. IN ADDITION...THE REGION WILL BE FAIRLY DRY WITH THE BETTER
MOISTURE LOCKED IN NEAR THE UPPER SYSTEM. ALL THESE NEGATIVE FACTORS
COMBINED WITH THE NEAR NEUTRAL OR SLIGHTLY ANTICYCLONIC LOW LEVEL
FLOW...ANY SHOWER ACTIVITY SHOULD BE MINIMAL OR NONE ON MONDAY AND
HAVE OPTED TO KEEP POPS OUT. TEMPS WILL BE COOL...WITH 850MB TEMPS
AROUND +6C ACROSS THE EAST. THE GFS IS COOLER AND SHARPER IN
DROPPING ENERGY INTO THE TROUGH...BUT THIS IS GENERALLY IN
DISAGREEMENT WITH THE OTHER OPERATIONAL MODELS. WILL THEREFORE GO
WITH TEMPS IN THE LOW-MID 60S EAST AND LOWER 70S WEST. THIS MAY BE A
LITTLE OPTIMISTIC AND MAY NEED TO BE ADJUSTED SLIGHTLY LOWER
ESPECIALLY IF THERE ARE MORE CLOUDS THAN FCST.
TUESDAY SHOULD BE QUIET AS HEIGHTS RISE ACROSS THE AREA. THE NAM
SUGGESTS THAT ANOTHER POCKET OF COLD AIR WILL DIVE INTO THE AREA
FROM NW ONTARIO BUT THIS IS ALSO AN OUTLIER COMPARED TO THE OTHER
OPNL MODELS. WITH THE HEIGHTS RISING ACROSS THE AREA...EXPECT TEMPS
TO WARM SLIGHTLY ON TUE...BUT STILL BE BELOW NORMAL GIVEN WITH HIGH
WILL BE OVERHEAD AND NE FLOW WILL CONTINUE ACROSS THE EAST.
MODELS BEGIN TO DIVERGE ON TUE NIGHT REGARDING THE STRENGTH AND
POSITION OF THE WARM ADVECTION PCPN TUE NIGHT. THE GFS SUGGESTS THAT
STRONG WARM ADVECTION PCPN WILL REMAIN SOUTH/WEST OF THE AREA WITH
THE WARM FRONT WHILE THE ECMWF AND GEM SUGGEST THAT THE BETTER LOW
LEVEL JET AND ASSOCIATED CONVERGENCE WILL BE OVER NRN MN INTO WRN
LAKE SUPERIOR AND EVEN WESTERN UPPER MI LATE TUE NIGHT INTO WED.
GIVEN THAT THE GFS IS HAVING SOME CHALLENGES WITH CONVECTIVE
PARAMETRIZATION...THE BAROCLINIC ZONE MAY ALSO BE A LITTLE TO FAR
SOUTH. THE EC AND THE GEM SHOW BETTER ISENTROPIC LIFT AND A STRONG
LLJ ACROSS THE NRN MN AND THE WESTERN LAKE LATE TUE NIGHT/WED AND
HAVE OPTED TO KEEP CHC POPS ACROSS THOSE AREAS/
NO MAJOR CHANGES PLANNED TO THE CURRENT EXTENDED FORECAST. THE 00Z
MODELS HAVE COME INTO BETTER AGREEMENT WITH THE MEAN PATTERN THROUGH
NEXT SATURDAY. ALTHOUGH RAIN/STORMS CANNOT BE TOTALLY RULED OUT ON
WEDNESDAY WITH WARM ADVECTION AND INCREASED MOISTURE ACROSS THE
WEST...THE ECMWF SUGGESTS THAT THE BETTER CHANCE FOR PCPN WILL BE
THU/THU NIGHT AS THE FRONT APPROACHES AND HAVE OPTED TO CONTINUE
WITH CHC POPS ACROSS THE ENTIRE REGION FOR THIS TIME. TEMPS AT 850MB
ARE SLIGHTLY LOWER WITH THIS RUN...NOW NOT REACHING +20C. HAVE
THEREFORE OPTED TO LOWER TEMPS SEVERAL DEGREES ACROSS THE ENTIRE
REGION. NOT SURE OF THE MOISTURE RETURN WITH THIS SYSTEM GIVEN ITS
PACIFIC ORIGIN AND LACK OF GULF MOISTURE. AFTER THE FRONT...HIGH
PRES BUILDS BACK OVER THE UPPER LAKES AND DRY WEATHER IS CURRENTLY
EXPECTED FOR NEXT SATURDAY WITH COOLER TEMPS.
AVIATION (FOR THE 18Z TAF ISSUANCE)
HIGH PRESSURE BUILDING IN WILL KEEP VFR CONDITIONS GOING AT
KCMX/KSAW THROUGH THE FORECAST PERIOD. WHILE WINDS WILL REMAIN
LIGHT...LAKE BREEZE DEVELOPS BY SUNDAY MORNING RESULTING IN WIND
SPEEDS OF UP TO 10 KNOTS AT KSAW. FORECAST SOUNDINGS INDICATE SOME
LOW CLOUDS DEVELOPING AROUND 05Z TONIGHT...HOWEVER...DUE TO DRYNESS
AT THE LOWEST LEVELS...DO NOT EXPECT ANY PRECIPITATION REACHING THE
GROUND.
MARINE (FOR THE 4 PM LAKE SUPERIOR ISSUANCE)
LIGHT ACCOMPANYING THE RIDGE OVER THE AREA WILL CONTINUE TONIGHT
THROUGH MONDAY. AS THE RIDGE SLOWLY DRIFT EAST AND A LOW PRESSURE
AREA APPROACHES LAKE SUPERIOR FROM THE WEST MID WEEK WINDS WILL PICK
UP TO 10 TO 20 KNOTS. UNDER THE INFLUENCE OF THE HIGH PRESSURE
SYSTEM...WINDS SHOULD REMAIN AT SPEEDS LESS THAN 20 KNOTS WITH WAVES
CALM TO THREE FEET THROUGH THE PERIOD.
MQT WATCHES/WARNINGS/ADVISORIES
NONE.
SYNOPSIS/SHORT TERM...DLG
LONG TERM...MRD
AVIATION...DLG
MARINE...DLG
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