Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 231118
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
718 AM EDT THU OCT 23 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 410 AM EDT THU OCT 23 2014

SEVERAL ITEMS OF NOTE THIS MORNING...LEADING TO AN ACTIVE SHORT
TERM FORECAST. HEADING FROM EAST TO WEST...A DEPARTING HIGH
PRESSURE RIDGE CONTINUES TO PRODUCE CLEAR SKIES OVER THE EASTERN
HALF OF UPPER MICHIGAN EARLY THIS MORNING. WITH RETURN SOUTHERLY
FLOW DEVELOPING OVER THE AREA...RADIATIONAL COOLING HAS BE LIMITED
AND KEPT LOWS FROM BRING AS COLD AS YESTERDAY. STILL...HAVE SEEN
SOME LOWS FALLING INTO THE LOWER 30S TO MID 20S OVER MUCH OF
THAT AREA. IN THE CENTRAL U.P. STRATUS AND FOG HAS AGAIN DEVELOPED
AND IS COVERING A GOOD PORTION OF IRON...MARQUETTE...AND DICKINSON
COUNTIES. VISIBILITY HAS BEEN A LITTLE MORE VARIABLE THAN LAST
NIGHT AND GENERALLY BOUNCING BETWEEN 1/2 AND 6 MILES. EXPECT THESE
LOW CLOUDS AND OCCASIONAL FOG TO CONTINUE INTO THE MORNING HOURS.
GOES CLOUD THICKNESS AROUND 1.1KFT WHICH WOULD INDICATE DISSIPATION
2.5-3HRS AFTER SUNRISE IN A NORMAL RADIATIONAL FOG SITUATION.
ALTHOUGH THIS IS A SLIGHT HYBRID...IT MATCHES SIMILAR DISSIPATION
TIME AS YESTERDAY AND USED THAT IDEA FOR THE FOG AND LOW STRATUS
THIS MORNING (MATCHES MOST MODELS FOR TIMING).

OVER THE WESTERN U.P. THERE HAVE BEEN SCATTERED SHOWERS AND EVEN
A FEW RUMBLES OF THUNDER OVER ONTONAGON COUNTY AND PORTIONS OF
WESTERN LAKE SUPERIOR. THIS IS TIED TO THE LEADING EDGE OF A SHARP
850-700MB THETA-E GRADIENT AND MOISTURE TRANSPORT. THESE SHOWERS
HAVE BEEN LIFTING TO THE NORTHEAST AND WILL SLOWLY SLIDE EASTWARD
WITH TIME AS THE GRADIENT SHIFTS TOWARDS CENTRAL UPPER MICHIGAN. AS
THIS GRADIENT CONTINUES EAST THROUGH THE DAY TODAY...THE SECONDARY
AREA OF SHOWERS ASSOCIATED WITH THE SURFACE-850MB TROUGH
AND 500MB SHORTWAVE (CURRENTLY IN EASTERN MINNESOTA) WILL BECOME
CO-LOCATED WITH THE THETA-E GRADIENT. IN ADDITION...THERE ARE TWO
SHORTWAVES ASSOCIATED WITH THIS UPPER TROUGH...ONE WILL STAY NORTH
OF THE CWA AND MOVE EAST THROUGH NORTHERN ONTARIO TODAY/TONIGHT. THE
SECOND STRONGER PIECE OF ENERGY (CURRENTLY MOVING INTO SOUTHWEST
MINNESOTA AND NORTHWEST IOWA) WILL SHIFT EAST-SOUTHEAST THROUGH
CENTRAL/SOUTHERN WISCONSIN. WHILE THE MAIN SHORTWAVES WILL MISS THE
AREA...THERE SHOULD BE ENOUGH UPPER LEVEL SUPPORT TO GO ALONG WITH
THE LOW LEVEL TROUGH AND CONTINUE TO LEAD TO SHOWERS MOVING EAST
ACROSS THE AREA TODAY. STILL STRUGGLE SOMEWHAT WILL HOW TO HANDLE
THE WORDING FOR TODAY. THINK THE SHOWERS WILL GENERALLY BE OFF/ON
FOR MUCH OF TODAY...THEN MORE STEADY OVER THE SOUTHERN CWA AS THE
SURFACE-850MB TROUGH MOVES THROUGH. THUS...WILL HAVE SCATTERED
SHOWERS (50 PERCENT) FOLLOWING THAT THE FORCING ALONG THE TROUGH
FROM WEST TO CENTRAL TODAY WITH THE BEST FOCUS OF LIKELY/NUMEROUS
SHOWERS OVER THE SOUTHERN PART OF THE U.P.

NOT COMPLETELY CONFIDENT ON THE HOW FAR EAST THE SHOWERS WILL
TRACK...BUT THE MODELS SEEM CONSISTENT ON THEM WEAKENING OVER THE
EASTERN CWA TONIGHT AS THE TWO PIECES OF SHORTWAVE SEPARATE FURTHER
AND WEAKEN THE ELONGATED ENERGY BETWEEN THEM. THUS...WILL SHOW POPS
GRADUALLY DIMINISHING OVER THE EASTERN HALF OF THE CWA TONIGHT. FOR
THE REST OF THE AREA...WHILE THE DEEP MOISTURE DEPARTS...MODELS
CONTINUE TO SHOW SOME LOW LEVEL MOISTURE LINGERING FOR A TIME
TONIGHT. THEREFORE...WILL HOLD ONTO CLOUDS OVER THE WEST-CENTRAL
DURING THE EVENING AND THEN SHOW DECREASING CLOUDS OVERNIGHT AS THE
DRY WEST-NORTHWESTERLY FLOW BEHIND THE TROUGH TAKES HOLD. IN
FACT...FAR WESTERN GOGEBIC COUNTY MAY EVEN TRY TO SCATTER OR CLEAR
OUT JUST BEFORE SUNSET AND PROVIDE THEM WITH THE ONLY OPPORTUNITY IN
THE U.P. TO SEE THE PARTIAL SOLAR ECLIPSE. IF IT TIMES OUT...THEY
WOULD CATCH THE TAIL END OF THE ECLIPSE AS THE SUN IS SETTING
(MAXIMUM OCCURS AT 445PM CDT). THIS CLEARING WILL COMBINE WITH THE
INCREASED MOISTURE FROM THE RECENT RAIN TO LEAD TO LOW CLOUDS/FOG
OVER THE CENTRAL AND PARTS OF EASTERN CWA. HAVE ADDED PATCHY/AREAS
OF FOG TO THE FORECAST...WITH THE GREATEST COVERAGE AND LOWEST
VISIBILITIES ONCE AGAIN OVER THE HIGHER TERRAIN OF CENTRAL UPPER
MICHIGAN WITH THE ADDED SUPPORT OF LIGHT SOUTHWESTERLY SURFACE
FLOW.

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 332 AM EDT THU OCT 23 2014

NAM SHOWS A 500 MB RIDGE OVER THE DESERT SW 12Z FRI WITH A SHORTWAVE
OVER THE CANADIAN ROCKIES. THIS SHORTWAVE HEADS EAST AND AFFECTS THE
UPPER GREAT LAKES FRI NIGHT WITH THE RIDGE BUILDING INTO THE PLAINS
SAT NIGHT. NAM BRINGS IN SOME 850-500 MB Q-VECTOR CONVERGENCE FRI
NIGHT WITH SOME LIMITED MOISTURE WHICH MOVES OUT SAT MORNING. LOOKS
LIKE THE BEST CHANCE FOR PCPN WILL STILL BE WELL NORTH AND EAST OF
THE AREA AND KEPT IN SLIGHT CHANCE POPS IN THE ERN CWA AS THE AREA
GETS BRUSHED BY THIS SHORTWAVE. ON SATURDAY...WILL BE QUITE GUSTY
FOR WINDS.

IN THE EXTENDED...GFS AND ECMWF SHOW A 500 MB TROUGH OVER THE
EASTERN U.S. WITH A BROAD RIDGE OVER THE PLAINS AND A TROUGH IN THE
PACIFIC NW 12Z SUN. THIS RIDGE BUILDS INTO THE UPPER GREAT LAKES 12Z
MON WITH TROUGHING MOVING INTO THE ROCKIES. THE TROUGH MOVES INTO
THE PLAINS 12Z TUE AND LINGERS INTO WED. THE ECMWF IS MORE AMPLIFIED
WITH THIS TROUGH THAN THE GFS IS AND SEEMS TO BE KEEPING A SOUTHERN
STREAM AND NORTHERN STREAM SHORTWAVES SEPARATE. GFS IS MUCH WEAKER
WITH THE SOUTHERN STREAM SHORTWAVE. WITH THE TROUGH IN THE AREA AND
A FRONT MOVING THROUGH THE AREA...CHANCES FOR PCPN LOOK GOOD WITH
TEMPERATURES GOING FROM ABOVE NORMAL AT THE BEGINNING OF THE
EXTENDED TO NEAR NORMAL AT THE END OF THE FORECAST. WILL BE DRY ON
SUNDAY.
&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 717 AM EDT THU OCT 23 2014

ANOTHER NIGHT OF LOW CLOUDS AND FOG AT KSAW CONTINUES AND
EXPECT THAT TO LAST THROUGH MUCH OF THE MORNING HOURS. AM A
LITTLE UNCERTAIN ON IF/WHEN THE LOW CLOUDS WILL DIMINISH...AS
MID/HIGH CLOUDS OF APPROACHING SHOWERS WILL LIMIT SUNSHINE TO MIX
OUT THE LOW CLOUDS. WILL FOLLOW THE IDEAS FROM THE MODELS OF IT
STARTING TO MIX OUT AROUND NOON.

FOR THE REST OF THE AREA AND PERIOD...SHOWERS ARE CURRENTLY
APPROACHING WESTERN UPPER MICHIGAN AND THEY WILL CONTINUE EASTWARD
ACROSS WESTERN UPPER MICHIGAN TODAY. STARTING TO SEE SOME OF THE
MVFR CEILINGS IN WESTERN WISCONSIN TO APPROACH KIWD AND SHOULD
IMPACT THE SITE WITHIN A COUPLE HOURS AFTER TAF ISSUANCE. THESE
SHOWERS WILL BRING MVFR CONDITIONS TO ALL THREE SITES AS THEY SLOWLY
PROGRESS EASTWARD. BEHIND THE SHOWERS THIS EVENING...EXPECT A
GRADUAL CLEARING TO OCCUR AND THAT WILL LIKELY LEAD TO FOG AT KCMX
AND ESPECIALLY KSAW. ONCE AGAIN...HAVE BROUGHT KSAW TO ALTERNATE
LANDING MINS DURING THE OVERNIGHT HOURS.
&&

.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 410 AM EDT THU OCT 23 2014

A TIGHTENING PRESSURE GRADIENT EARLY THIS MORNING BETWEEN A HIGH
PRESSURE RIDGE OVER THE CENTRAL GREAT LAKES AND A LOW NEAR LAKE
WINNIPEG WILL LEAD TO OCCASIONAL GUSTS TO 20-25KTS OVER THE CENTRAL
AND EASTERN GREAT LAKES. AS THE LOW WEAKENS TONIGHT...THE PRESSURE
GRADIENT WILL ALSO WEAKEN AND LEAD TO LIGHTER WINDS OVER LAKE
SUPERIOR. A MUCH STRONGER LOW DEVELOPING OVER NORTHERN SASKATCHEWAN
ON FRIDAY WILL MOVE EAST TO SOUTHERN HUDSON BAY ON
SATURDAY...DRAGGING A COLD FRONT SOUTHEAST ACROSS THE UPPER GREAT
LAKES. BEHIND THE COLD FRONT...A TIGHT PRESSURE GRADIENT BETWEEN
THE LOW AND A HIGH IN THE NORTHERN PLAINS WILL LEAD TO
WEST-NORTHWEST WINDS UP TO 30KTS ON SATURDAY (WITH A FEW GALE FORCE
GUSTS TO 35KTS POSSIBLE OVER EASTERN LAKE SUPERIOR). AS THE HIGH
SHIFTS EAST INTO THE UPPER GREAT LAKES SATURDAY NIGHT INTO
SUNDAY...WINDS WILL DIMINISH BELOW 20KTS. A ANOTHER DEVELOPING LOW
IN THE NORTHERN PLAINS ON SUNDAY NIGHT WILL SHIFT WINDS AROUND TO
THE SOUTH-SOUTHEAST AND INCREASE UP TO 25KTS ON MONDAY.
&&

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

$$

SHORT TERM...SRF
LONG TERM...07
AVIATION...SRF
MARINE...SRF






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