Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 231958
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
358 PM EDT WED JUL 23 2014

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 357 PM EDT WED JUL 23 2014

A 500MB RIDGE EXTENDS FROM THE SOUTHWESTERN UNITED STATES INTO THE
CANADIAN PRAIRIES THIS AFTERNOON. LOW PRESSURE DROPPING INTO THE
NORTHWESTERN UNITED STATES FROM THE GULF OF ALASKA TONIGHT WILL
SWEEP INTO ALBERTA BY THURSDAY NIGHT. THIS WILL BREAK DOWN THE RIDGE
AND ALLOW LOW PRESSURE OVER QUEBEC TO SINK SLIGHTLY INTO JAMES BAY.
AT THE SURFACE...HIGH PRESSURE CENTERED OVER MN AND THE UPPER GREAT
LAKES WILL SINK SOUTH-SOUTHEAST INTO THE OHIO RIVER VALLEY BY
THURSDAY EVENING.

EXPECTING A PRETTY QUIET SHORT TERM FORECAST. WINDS WILL BE LIGHT
WITH THE HIGH PRESSURE CENTER OVERHEAD TONIGHT. LOW TEMPERATURES
WILL BE ON THE COOLER SIDE FOR THIS TIME OF YEAR. LIGHT WINDS AND
MOSTLY CLEAR SKIES TONIGHT WILL DROP LOWS INTO THE UPPER
30S-40S...WITH THE COLDEST TEMPERATURES INLAND WEST. PATCHY FROST IS
POSSIBLE IN THESE COLDER LOCATIONS. AS ALWAYS...THERE IS A SLIGHT
WRENCH IN THE FORECAST. WILL WE SEE CLOUD COVER CLEARING THIS
EVENING OUT WEST...HENCE THE COOLER TEMPERATURES AND PATCHY
FROST...OR WILL WE SEE LINGERING CLOUD COVER/MOISTURE...WARMER
TEMPERATURES...AND SOME FOG DEVELOPMENT?

WHILE OTHER MODELS HAVE US CLEAR AND DRY...THE NAM HANGS ONTO THIS
CLOUD COVER/MOISTURE IN THE WEST...AND THEN BRINGS A QUICK BATCH OF
SECONDARY LOW LEVEL MOISTURE ACROSS THE KEWEENAW AND THE EASTERN CWA
LATE TONIGHT. WITH SUBSIDENCE BRINGING INVERSION HEIGHTS DOWN...
THINKING THIS COULD SPUR OFF SOME PATCHY FOG. NORMALLY WOULD THINK
THE NAM IS OVERDOING THE MOISTURE AGAIN...BUT WHEN OTHER MODELS WERE
COMPLETELY CLEARED OUT THIS MORNING/AFTERNOON...THE NAM CAUGHT ON TO
SOME FOG THAT HAD DEVELOPED NEAR MUNISING/GRAND MARAIS...AND SOME
LINGERING MOISTURE/DAYTIME HEATING CLOUD COVER IN THE WEST THIS
AFTERNOON.

STILL NOT COMPLETELY CONVINCED WITH THE NAMS EXTENSIVE CLOUD COVER
FOR THE WEST TONIGHT GIVEN THE INCOMING HIGH...AND I THINK THE CU
FIELD WILL DIMINISH WITH DAYTIME HEATING. HOWEVER IT COULD BE
CATCHING ONTO SOME FOG DEVELOPMENT. OVERALL...PLAYED IT SAFE AND
KEPT MOSTLY CLEAR TO PARTLY CLOUDY SKIES THROUGH MORNING...AND HAVE
PATCHY FOG DEVELOPING ALONG THE WI BORDER...EAST...AND OVER THE
KEWEENAW.


HIGH TEMPERATURES WILL BE A BIT WARMER ON THURSDAY AS THE AIRMASS
MODIFIES AND MOSTLY SUNNY SKIES ABOUND. 850MB TEMPS OF 8C TO 11C
WOULD PUT HIGHS IN THE UPPER 60S NEAR THE LAKE SHORE AND THE
MID/UPPER 70S INLAND. THOUGH IT WILL BE DRY /RH IN SOME LOCATIONS IN
THE UPPER 20-30 PERCENT RANGE/ LIGHT WINDS WILL KEEP ANY FIRE WX
CONCERNS AT BAY. SOME OF THE MODELS ARE GENERATING PRECIPITATION
CHANCES OVER LAKE SUPERIOR THURSDAY AFTERNOON WITH A WEAK SHORTWAVE
ASSOCIATED WITH THE LOW OVER QUEBEC. THOUGH THERE IS WEAK LIFT
ASSOCIATED WITH THE WAVE THINK IT IS TOO DRY FOR ANY PRECIPITATION
TO DEVELOP...SO HAVE LEFT ANY CHANCES OUT.

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 357 PM EDT WED JUL 23 2014

SFC HI PRES UNDER UPR RDG WL BRING DRY WX INTO AT LEAST EARLY FRI...
THEN SHOWER/TS CHCS WL BE INCRSG BY LATE FRI THRU THE WEEKEND AS SW
FLOW AHEAD OF CLOSED LO NOW OFF THE PAC NW AND MOVING ACRS SRN
CANADA BRINGS A RETURN OF MORE HUMID AIR. MUCH COOLER AIR WL INVADE
THE UPR LKS SUN THRU NEXT WEEK ONCE THE DIGGING SHRTWV SLIDES
ESEWD THRU THE GREAT LKS AND OPENS THE DOOR TO COOLER CNDN AIR UNDER
DEEPENING UPR TROF.

THU NGT...SFC HI PRES IS FCST TO MOVE INTO THE MID ATLANTIC STATES
BY FRI MRNG. RETURN SW FLOW BTWN THIS HI AND LO PRES DVLPG IN THE
NRN PLAINS IN ADVANCE OF CLOSED LO MOVING INTO SCENTRAL CANADA IS
FCST TO ADVECT MOISTER AIR BACK INTO THE AREA WITH PWAT RISING
TOWARD 1.25 INCH OVER THE W BY 12Z FRI. COMBINATION OF THIS
RETURNING MSTR/AT LEAST PTCHY CLDS AND SW FLOW WL LIMIT THE DIURNAL
FALL OF TEMP...ESPECIALLY OVER THE W. EXPECT THE COOLEST MIN TEMPS
IN THE UPR 40S OVER THE INTERIOR E UNDER THE LINGERING DRY AIR.

FRI...AS CLOSED LO DRIFTS INTO SRN SASKATCHEWAN AND SFC HI PRES
DRIFTS OFF THE E COAST...SW FLOW WL PUMP PWAT BACK TO ARND 1.5
INCHES...RESULTING IN MORE WAD CLDS. MODELS DO DIFFER ON MAGNITUDE
OF DEEP LYR QVECTOR CNVGC/EXTENT OF DEEP MOISTENING/QPF. ALTHOUGH
THE 06Z AND 12Z GFS GENERATE PCPN OVER MAINLY THE W HALF OF THE
CWA...FCST SDNGS SHOW SHARP CAPPING INVRN THAT WOULD INHIBIT
SHOWERS. WHILE THE 00Z ECWMF/12Z NAM ARE DRY...THE 12Z CNDN MODEL IS
VERY AGGRESSIVE AT GENERATING PCPN...WITH AS MUCH AS 0.50-0.75 INCH
FCST OVER THE W THRU THE DAY WITH PWAT FCST AS HI AS 1.75 INCH AND
DEEP SATURATION SHOWN ON FCST SDNGS. LOCATION OF SHARPER WARM FNT
WELL TO THE SW THAT WOULD BE FOCUS FOR MORE SGNFT MSTR CNVGC WL
RESTRICT POPS. SINCE UPR MI IS FCST TO BE UNDER SFC-H85 RDG
AXIS/ACYC FLOW BTWN THAT WARM FNT AND ANOTHER FNT OVER ONTARIO THAT
WL BE INFLUENCED BY UPR DVGC IN THE RRQ OF AN H3 JET MAX PASSING
THRU ONTARIO...SUSPECT THE DRIER MODELS ARE ON THE RIGHT TRACK. BUT
OPTED TO INCLUDE SOME LO CHC POPS TO ACCOUNT FOR THE CONSIDERABLE
UNCERTAINTY IN THE MODEL FCSTS.

FRI NGT THRU SUN...CLOSED LO OVER SE SASKATCHEWAN ON FRI NGT IS FCST
TO SLIDE SE AND THRU WI ON SUN. THERE IS MUCH UNCERTAINTY AMONG THE
GUIDANCE ON QPF OVER UPR MI DURING THE FRI NGT INTO SAT NGT TIME
WHEN THE SHRTWV/SHARPER DYNAMIC FORCING IS STILL FARTHER TO THE W
BUT WHEN HIER PWAT REMAINS OVHD IN THE GENERAL SW FLOW AHEAD OF THE
SHRTWV. THERE APPEARS TO A BETTER CONSENSUS AMONG THE MODELS SHOWING
AN AXIS OF SOME DEEP LYR QVECTOR CNVGC PASSING W-E ARND 12Z SAT...
SO SOME HIER CHC POPS ARE WARRANTED ATTM. BEST CHC FOR SHOWERS LOOKS
TO BE LATE SAT NGT INTO SUN WHEN UPR MI IS CLOSER TO AND ON THE CYC
SIDE OF THE SHRTWV TRACK AND ACCOMPANYING DPVA/UPR DVGC/DEEP LYR
QVECTOR CNVGC WOULD IMPACT THE AREA. AS THE SHRTWV DIGS TO THE SE ON
SUN AND SFC LO TAKES SHAPE OVER SRN LOWER MI TO THE E OF TRAILING
SFC HI PRES MOVING INTO THE NRN PLAINS...A STRENGTHENING N WIND WL
DVLP OVER THE UPR LKS AND ADVECT MUCH COOLER AIR INTO THE UPR LKS.
IN FACT...TEMPS MAY REMAIN NEARLY STEADY/SLOWLY FALL THRU THE 50S ON
SUN NEAR LK SUP WITH SHARP UPSLOPE N WIND OFF THE CHILLY LK WATERS.

EXTENDED...MODELS FCST H85 TEMPS AS LO AS 3-5C ON MON UNDER
DEEPENING UPR TROF/STRENGTHENING NLY FLOW BTWN LO PRES OVER THE SE
GREAT LKS AND HI PRES MOVING INTO THE PLAINS. THESE TEMPS ARE FCST
TO MODERATE TO 10-13C BY NEXT WED...SO TEMPS SHOULD RECOVER A BIT BY
MID WEEK FM THE WELL BLO NORMAL VALUES ON MON. ALTHOUGH SHARP CYC
FLOW ON MON IS FCST TO SLOWLY WEAKEN THRU WED AS SFC LO PRES LIFTS
NWD THRU QUEBEC...LINGERING THERMAL TROF/CYC NATURE OF THE FLOW/
SHRTWVS ROTATING ARND THE UPR TROF AXIS TO THE E OF THE CWA MAY
SUPPORT SOME DIURNAL SHOWERS...MAINLY AWAY FM THE STABILIZING
INFLUENCE OF THE LKS EARLY IN THE WEEK WHEN HEIGHTS ARE LOWER CLOSER
TO THE SLOWLY DEPARTING SFC LO. RIGHT NOW...THE UPR TROF/AXIS OF
LOWER HGTS IS FCST TO BE FAR ENUF TO THE E TO LIMIT THESE POPS.
&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 136 PM EDT WED JUL 23 2014

WITH HIGH PRESSURE MOVING INTO UPPER MI...PRIMARILY VFR CONDITIONS
ARE EXPECTED AT ALL SITES THROUGH THE FORECAST PERIOD. KCMX MAY SEE
SOME FOG DEVELOP LATE TONIGHT AFTER 6Z WITH LOW LEVEL MOISTURE
TRAPPED BENEATH THE INVERSION...THOUGH CONFIDENCE IS NOT VERY HIGH.
FOR NOW...DROPPED VISIBILITY DOWN TO 3 MILES DURING THIS TIME. LATER
SHIFTS MAY ADJUST ONCE THEY OBSERVE FOG DEVELOPING.
&&

.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 357 PM EDT WED JUL 23 2014

EXPECT WINDS UNDER 20 KTS THRU SAT NGT WITH RELATIVELY WEAK PRES
GRADIENT DOMINATING THE UPPER LAKES. STRONGER N WINDS UP TO 25 KTS
ARE POSSIBLE ON SUN INTO MON AS COOLER AIR INVADES THE AREA UNDER
TIGHTER GRADIENT BETWEEN HI PRES MOVING INTO THE NORTHERN PLAINS AND
LO PRES OVER THE SE GREAT LAKES.
&&

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

$$

SHORT TERM...MCD
LONG TERM...KC
AVIATION...MCD
MARINE...KC



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