Area Forecast Discussion
Issued by NWS Marquette, MI

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000
FXUS63 KMQT 221900
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
300 PM EDT FRI AUG 22 2014

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 252 PM EDT FRI AUG 22 2014

...STAYING HUMID BUT ONLY ISOLD SHOWERS/THUNDERTORMS...

WV LOOP AND 12Z H7-H5 RAOBS SHOW UPPER MISSISSIPPI RIVER VALLEY INTO
THE WESTERN GREAT LAKES IS WITHIN WEST/NORTHWEST FLOW ALOFT BTWN
TROUGH OVER NORTHERN ROCKIES AND RIDGE CENTERED OVER SOUTHERN UNITED
STATES. PRIMARY SFC FRONT IS ORIENTED FM WESTERN KS ACROSS IA AND
NORTHERN ILLINOIS TO NORTHERN OHIO. AIRMASS SOUTH OF THE FRONT MORE
OPPRESSIVELY HUMID WITH DWPNTS WELL INTO THE 70S. DWPNTS NORTH OF
THE FRONT...INCLUDING INTO THE UPR GREAT LAKES ARE STILL HUMID WITH
MAINLY 60S SEEN. MOST OF THE SHRA/TSRA ARE ONGOING ALONG THE FRONT
CLOSER TO GREATER INSTABILITY. RADAR OVER THE UPR GREAT LAKES DOES
SHOW ISOLD SHRA WITH SOMEWHAT BETTER COVERAGE OVER NORTHERN WI AND
INTO CNTRL UPR MICHIGAN CLOSER TO A WEAK SFC-H85 WAVE AND ALSO WHERE
H85-H7 THETA-E RIDGE IS MORE PRONOUNCED. VERY LITTLE IN WAY OF
SHORTWAVES AND LARGE SCALE LIFT ON TOP OF THE RIDGE...BUT THERE IS
A STRONGER WAVE/COLDER CLOUD TOPS SEEN OVER THE DAKOTAS. REGIONAL
RADAR SHOWS SHRA/ISOLD TSRA WITH THE SHORTWAVE FM NE INTO DAKOTAS
AND NORTHERN MN.

REST OF AFTN INTO EARLY EVENING SHOULD REMAIN MOSTLY CLOUDY. SHRA
AND PERHAPS A TSRA MAINLY WEST HALF...ESPECIALLY CLOSER TO WI
BORDER...MOSTLY DUE TO THE PROXIMITY OF THE H85-H7 THETA-E RIDGE AND
1-6KM MUCAPES UP TO 200J/KG. LIMITED FORCING WILL RESULT IN ONLY
ISOLD COVERAGE TO ANY SHRA...THOUGH ANY SHRA COULD PRODUCE HEAVY
DOWNPOURS GIVEN PWATS OVER 175 PCT OF NORMAL. TEMPS IN THE 70S WITH
DWPNTS IN THE 60S AND NOT MUCH WIND WILL KEEP CONDITIONS ON THE HUMID
SIDE.

LATER THIS EVENING AND ON INTO THE OVERNIGHT HOURS...SHORTWAVE OVER
DAKOTAS MOVES EAST...BUT IT WILL PROBABLY WEAKEN WHILE PUSHING INTO
THE BUILDING RIDGE. ALSO...EXPECT H85-H7 THETA-E RIDGE TO LIFT MORE
ACROSS UPR MICHIGAN WHILE ALSO WEAKENING. SFC WAVE OVER WI WILL ALSO
BE FILLING...WITH HIGHER PRESSURE DEVELOPING OVER UPR LAKES. MAIN
SHORT TERM MODEL DIFFERENCE DEALS WITH HOW FAR EAST THETA-E RIDGE
AXIS PROGRESSES AND THUS HOW FAR EAST SMALL CHANCES FOR SHRA WILL BE.
EVEN THOUGH COVERAGE WILL REMAIN LIMITED...HEAVY DOWNPOURS...WILL
STILL BE POSSIBLE WITH STEERING WINDS LESS THAN 10 KTS AND PWATS
175-200PCT OF NORMAL/K INDEX VALUES AROUND 35. TSRA CHANCES MEAGER
THOUGH AS WHATEVER MUCAPE IS AROUND EARLY THIS EVENING IS NIL AFT 03Z.
LOW-LEVEL INVERSION COULD RESULT IN FOG FORMING LATER TONIGHT...BUT
SINCE CLOUD DEPTH REMAINS FAIRLY DEEP...THROUGH AROUND H8...SHOULD BE
MORE OF A STRATUS/1-3SM VSBY SETUP INSTEAD OF WIDESPREAD DENSE FOG.

INTO SATURDAY...H85-H7 THETA-E RIDGE SEEMS TO REFOCUS OVER MAINLY
WESTERN CWA BY LATE MORNING. NEUTRAL TO ANTICYCLONIC LOW-LEVEL FLOW
WILL BE IN PLACE AS THE SFC LOW WILL HAVE DISSIPATED. IF THERE IS
ANY POTENTIAL OF SHRA ON SATURDAY AFTERNOON...EXPECT IT TO BE WITHIN
THAT THETA-E RIDGE AXIS AND ALSO DUE TO LIFT AHEAD OF SHORTWAVE
MODELS SHOW EMERGING OUT OF NEB THIS AFTN. MLCAPES UP TO 200J/KG AND
H8-H7 WINDS FM THE SOUTH COULD ALSO ALLOW A TSRA TO AFFECT FAR WEST
UPR MICHIGAN IN THE AFTN. ELSEWHERE OVER CNTRL AND EAST CWA...EXPECT
MOSTLY CLOUDY SKIES TO GRADUALLY THIN OUT WITH PROBABLY MORE
SUNSHINE SEEN THAN THE LAST COUPLE DAYS. MORE SUNSHINE COMBINED WITH
H85 TEMPS AROUND 15C ON AVERAGE SHOULD RESULT IN TEMPS IN THE MID
70S TO AROUND 80. LOWEST READINGS WILL OCCUR OVER FAR WEST WITH MORE
CLOUD COVER EXPECTED THERE. DWPNTS IF ANYTHING MAY BE SLIGHTLY HIGHER
IN MID-UPR 60S...SO IT WILL CONTINUE TO BE HUMID.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 456 AM EDT FRI AUG 22 2014

A PRONOUNCED RIDGE WILL DEVELOP OVER THE LENGTH OF THE MISSISSIPPI
VALLEY TODAY/SAT AS A TROF SETTLES INTO THE ROCKIES. ONE PIECE OF
ENERGY IN THE TROF WILL LIFT NE LATE IN THE WEEKEND/EARLY NEXT
WEEK...SUPPRESSING AND FORCING THE RIDGE EASTWARD SO THAT THE AXIS
EXTENDS THRU THE LOWER LAKES TO NEW ENGLAND MON. THE TROF WILL THEN
BECOME MUCH MORE PROGRESSIVE EARLY/MIDDLE OF NEXT WEEK AS MORE
ENERGY SWINGS THRU THE TROF. END RESULT OF THESE CHANGES WILL BE
SEVERAL DAYS OF WARM/HUMID WEATHER EXTENDING INTO THE EARLY PART OF
NEXT WEEK...AND THEN A CHANGE TO COOLER WEATHER FOR THE MIDDLE TO
END OF THE WEEK AS THE TROF PASSES. AS FOR PCPN...PATTERN THRU THE
WEEKEND WILL SUPPORT SOME POTENTIAL FOR PCPN AT TIMES...THOUGH
LIMITED AS HEIGHTS/RIDGE BUILD OVER AREA. PIECE OF ENERGY LIFTING NE
OUT OF WRN TROF LATE WEEKEND/EARLY NEXT WEEK WILL LIKELY TAKE A
TRACK FAR ENOUGH W AND NW TO PRECLUDE A SIGNIFICANT PCPN CHC AS
HEIGHT FALLS WILL BE WEAK AS COLD/OCCLUDED FRONT SWINGS E ACROSS THE
UPPER LAKES. ANOTHER SHOT OF PCPN MAY OCCUR MIDWEEK AS ADDITIONAL
ENERGY SWINGING THRU THE INCREASINGLY PROGRESSIVE TROF MAY GENERATE
A LOW PRES WAVE THAT WILL LIFT NE INTO THE WRN GREAT LAKES.
HOWEVER...MEDIUM RANGE GUIDANCE OVER THE LAST COUPLE OF DAYS HAS
SHOWN CONSIDERABLE SPREAD IN TRACK/STRENGTH OF THIS WAVE OR EVEN ITS
DEVELOPMENT.

BEGINNING SAT...THERE MAY BE A FEW SHRA OVER THE WRN PORTION OF THE
FCST AREA...MAINLY IN THE MORNING...IN THE VCNTY OF SUBTLE DECAYING
LOW-LEVEL TROF AND WITHIN LOW-LEVEL THETA-E RIDGE. OTHERWISE...
STEADILY RISING HEIGHTS/BUILDING RIDGE AND POOR MID LEVEL LAPSE
RATES (MOIST ADIABATIC) SUGGEST A TREND TO A DRY DAY IS LIKELY IN
THE OFFING. MIXING TO AROUND 850MB ON FCST SOUNDINGS SUPPORTS AFTN
HIGH TEMPS GENERALLY IN THE MID 70S TO AROUND 80. WARMEST READINGS
(PERHAPS MID 80S) MAY BE OVER THE INTERIOR E DUE TO DRIER AIR MASS
ALLOWING FOR DEEPER MIXING. COOLER CONDITIONS WILL BE NOTED ALONG
THE LAKESHORES AFFECTED BY DEVELOPING EASTERLY WINDS.

AS ENERGY IN THE WRN TROF LIFTS NE THRU THE ROCKIES TOWARD THE WRN
DAKOTAS SAT NIGHT...LOW-LEVEL JET WILL CRANK UP THRU THE PLAINS.
WITH ONLY THE ERN EDGE OF THE STRONGER WINDS BRUSHING WRN UPPER
MI...SHRA/TSRA CHC LOOKS MINIMAL. WILL ONLY INCLUDE CHC OVER WRN
LAKE SUPERIOR...LOWERING TO SCHC OVER WRN UPPER MI.

PCPN CHANCES ON SUN WILL DEPEND ON HOW FAR E HEIGHT FALLS SPREAD
INTO THE WRN GREAT LAKES. GIVEN THAT MODELS SHOW LITTLE OR NO HEIGHT
FALLS INTO UPPER MI...WILL CONTINUE TO KEEP JUST SCHC POPS LIMITED
TO WRN UPPER MI SUN. WITH 850MB THERMAL RIDGE BUILDING TOWARD THE
UPPER LAKES...SUN WILL BE WARMER/MORE HUMID WITH HIGHS IN THE UPPER
70S TO MID 80S.

COLD OR OCCLUDED FRONT WILL DRIFT ACROSS THE AREA SUN NIGHT/MON.
SINCE THERE IS A LACK OF SIGNIFICANT HEIGHT FALLS...NOTHING MORE
THAN CHC POPS WILL BE UTILIZED...SPREADING W TO E ACROSS THE AREA.
THE W HALF SHOULD DRY OUT MON AFTN. MON WILL STILL BE WARM/HUMID...
AT LEAST OVER CNTRL UPPER MI.

MAY BE ABLE TO SLIP IN A PERIOD OF DRY WEATHER MON NIGHT INTO PART
OF TUE AS WEAKENING FRONTAL BOUNDARY SHIFTS E OF THE AREA.
ATTENTION THEN TURNS TO POTENTIAL FOR A WAVE TO LIFT NE INTO THE
GREAT LAKES IN RESPONSE TO ADDITIONAL ENERGY SWINGING THRU
INCREASINGLY PROGRESSIVE TROF. GFS HAS SHOWED REASONABLE CONSISTENCY
ON THIS SCENARIO WHILE THE ECMWF HAS BEEN UNCHARACTERISTICALLY
INCONSISTENT. HOWEVER...THE 00Z ECMWF WHICH HAS A LOW AMPLITUDE TROF
IS SIMILAR TO THE GEM AND UKMET...SUGGESTING LESS PCPN POTENTIAL. AT
THIS POINT...A CONSENSUS APPROACH WILL BE UTILIZED...RESULTING IN
CHC POPS FOR LATER TUE INTO WED. COOLER WEATHER WILL ALSO FOLLOW FOR
WED/THU AS TROF PASSES.
&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 142 PM EDT FRI AUG 22 2014

PREVAILING CIGS THIS AFTN MOSTLY MVFR AT ALL THE TAF SITES. STRENGTHENING
INVERSION TONIGHT AND PLENTY OF MOISTURE BENEATH THE INVERSION COULD
ALLOW FOR LOW STRATUS AND EVEN FOG TO DEVELOP LATE TONIGHT INTO
SATURDAY MORNING. BEST CHANCE OF IFR VSBY AT KIWD. ISOLD SHRA REMAIN
POSSIBLE AT KCMX AND KSAW INTO TONIGHT. TSRA CHANCES APPEAR QUITE
LIMITED. IF A SHRA IMPACTS THE TERMINAL COULD SEE BRIEF HEAVY RAIN.
&&

.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 252 PM EDT FRI AUG 22 2014

RELATIVELY WEAK PRESSURE GRADIENT WILL KEEP WINDS BELOW 20 KTS INTO
SATURDAY. PRESSURE GRADIENT TIGHTENS UP SUNDAY INTO MONDAY AS A LOW
PRESSURE SYSTEM MOVES NORTHWEST THEN NORTH OF LK SUPERIOR. SOUTHEAST
WIND GUSTS TO 25 KTS EXPECTED SUNDAY AFTN AND EVENING AHEAD OF THE
LOW...THEN ON MONDAY BEHIND A COLD FRONT...EXPECT WEST TO SOUTHWEST
WINDS GUSTING TO 25 KTS. AREAS OF MIST...WITH PATCHES OF DENSE FOG...WILL
DIMINISH BY EARLY NEXT WEEK. &&

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

$$

SHORT TERM...JLA
LONG TERM...ROLFSON
AVIATION...JLA
MARINE...JLA







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