Area Forecast Discussion
Issued by NWS Twin Cities, MN

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000
FXUS63 KMPX 220023
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
723 PM CDT THU AUG 21 2014

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 340 PM CDT THU AUG 21 2014

SFC ANALYSIS SHOWS A LOW PRES CENTER NEARLY ATOP THE TWIN CITIES
METRO...WITH A CDFNT EXTENDING SWWD TO NEAR KRWF AND A WMFNT
EXTENDING SEWD TO NEAR KRGK. LOW CLOUDS REMAINED STEADFAST OVER
MUCH OF THE WFO MPX CWFA FOR MUCH OF THE DAY...ASIDE FROM THE WARM
SECTOR OF THIS SYSTEM WHICH ALLOWED SRN MN TO HAVE PLENTY OF SUN
AND ALSO SEE TEMPS RISE TO THE MID 80S TO ARND 90 DEGREES. HENCE
WHY THE HEAT ADVY HAS BEEN ADJUSTED TO JUST ACCOUNT FOR A HANDFUL
OF COUNTIES IN SRN MN THRU THE REST OF THE AFTN HRS. IN
ADDITION...THIS WARM SECTORING IS THE FOCUS AREA FOR POTENTIAL
ISOLD STRONG/SEVERE TSTMS DUE TO NEARLY NO CAPPING...MUCAPES OVER
3000 J/KG /AND PLENTY OF OTHER SEVERE INDICES INDICATING THE SAME/
AND LIFT PROVIDED BY THE FRONT ALONG WITH SEVERAL OUTFLOW
BOUNDARIES DEPICTED ON KMPX RADAR. N OF THIS SYSTEM...AREAS CAUGHT
UNDER THE CLOUD COVER HAVE HAD TEMPERATURES HOLDING IN THE 70S
ALONG WITH DEWPOINTS IN THE UPR 60S TO LWR 70S. OUT IN WRN
MN...WINDS HAVE SHIFTED TO NWLY AND SOME PARTIAL CLEARING HAS
ALLOWED TEMPS SO RISE TO THE LOW-MID 80S BUT STILL WITH DEWPOINTS
IN THE LOW-MID 70S. OVERALL...A QUITE THE MUGGY DAY. WITH REGARD
TO POPS...HAVE KEPT THE HIGHEST POPS OUT IN WRN WI TO FAR ERN
MN...BUT OVERALL POPS ARE NOT ANY HIGHER THAN THE CHANCE CATEGORY.
GOING INTO THE EVENING HRS...ONCE THE CDFNT SWINGS THRU... THAT
WILL HELP STABILIZE THE ATMOS AND BRING IN SLIGHTLY COOLER TEMPS
BUT WILL NOT MITIGATE THE MOIST ATMOS. GIVEN THE CLEARING SKIES
AND CALMING WINDS...THIS SETUP WILL BE PRETTY IDEAL FOR WIDESPREAD
FOG...AND FAIRLY THICK FOG AT THAT. CROSSOVER TEMPS LOOK TO EASILY
BE REACHED SO HAVE MAINTAINED WIDESPREAD FOG DOWN TO 1/2SM IN
GRIDDED AND TEXT PRODUCTS. AM EXPECTING THE ENTIRE CWFA TO BE
SUSCEPTIBLE...INCLUDING THE TWIN CITIES METRO...THOUGH THE METRO
IS LIKELY NOT TO BE AS AFFECTED AS OUTLYING AREAS. ANY FOG WILL BE
SLOW TO DISSIPATE AFTER DAYBREAK IN FRI MRNG...BUT WITH THE SYSTEM
OF TDA EXITING TO THE E AND ANOTHER SFC FRONT LINGERING IN THE
DAKOTAS...MN AND WI WILL BE IN A RATHER STABLE ENVIRONMENT FOR FRI
SUCH THAT NO PRECIP IS EXPECTED FOR THE WFO MPX CWFA. WILL LOOK
FOR LESS OF A TEMP SPREAD FROM N TO S TMRW...WITH HIGHS FROM THE
UPR 70S TO MID 80S. DEWPOINTS WILL ALSO BE LOWER...TRANSLATING TO
HEAT INDEX VALUES HITTING THE UPR 80S TO ARND 90.

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 340 PM CDT THU AUG 21 2014

LONG TERM MODELS HAVE COME INTO BETTER AGREEMENT WITH OVERALL
DEVELOPMENT/MOVEMENT OF THE WESTERN CONUS TROUGH DURING THE
PERIOD.

RETURN FLOW AHEAD NEXT DEVELOPING SHORT WAVE WILL BEGIN TO AFFECT
MAINLY THE FAR SOUTHWEST CWA LATER FRIDAY NIGHT. FOG MAY BECOME AN
ISSUE ELSEWHERE...ESPECIALLY THE NORTHEAST CWA...WITH LIGHT WINDS
AND ONLY MARGINAL CLOUD COVER. THE WAVE LIFTS NORTHEAST SATURDAY
INTO SATURDAY NIGHT WITH HIGH PERCEPTIBLE WATER VALUES ALONG WITH
DECENT FORCING. WE SHOULD SEE GOOD SHOT OF HEAVIER QPF OVER THE
WESTERN AND CENTRAL CWA DURING THIS PERIOD. WILL CONTINUE TO LIMIT
THE HIGHEST POPS TO THE WEST.

THE SURFACE FRONT REMAINS MAINLY TO THE WEST OF THE STATE THROUGH
SATURDAY NIGHT. THE UPPER TROUGH MOVES A BIT MORE EAST INTO SUNDAY
AS THE UPPER LOW AND SURFACE LOW PIVOTS SOME INTO SOUTHERN
CANADA. HEAT RETURNS AHEAD OF THE FRONT...MAINLY EAST...WITH
HIGHER DEWPOINTS. WILL HAVE TO MONITOR FOR CLOUD COVER AGAIN...BUT
BETTER SOUTHERLY FLOW IN THE WAKE OF THE SATURDAY NIGHT SHORT WAVE
SHOULD BE ABLE CLEAR SOME. THE COLD FRONT WILL MOVE EAST LATER
SUNDAY THROUGH SUNDAY NIGHT. HAVE INCREASED POPS TO THE EAST INTO
SUNDAY NIGHT AS THE FRONT MOVES THROUGH. COOLER AND DRIER AIR WILL
MOVE IN FOR MONDAY BUT THE MAIN WESTERN CONUS TROUGH DOESNT MOVE
EAST UNTIL WEDNESDAY. ANOTHER HEAVY BOUT OF RAIN POSSIBLE TUESDAY
OVER THE SOUTH AND SPREADING EAST TUESDAY NIGHT INTO WEDNESDAY.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 649 PM CDT THU AUG 21 2014

LOW PRESSURE MOVING OVERHEAD TONIGHT WILL CAUSE AVIATION PROBLEMS
THROUGH THE TAF PERIOD. WE`LL START OUT DEALING WITH ISOLATED
SHOWERS AND THUNDERSTORMS THIS AFTERNOON...HENCE THE VCSH WORDING
AT SOME SITES. WIDESPREAD LOW STRATUS TO THE NORTH WILL CONTINUE
TO IMPACT AXN AND STC THIS EVENING...BUT BOTH SITES WILL FLIRT
WITH THE EDGE OF THE MAIN CLOUD DECK WHICH IS FURTHER NORTH. DEW
POINT TEMPERATURES WILL REMAIN HIGH...AND WIND WILL BE NEARLY CALM
THROUGH THE NIGHT. SO...AS EARLIER SHIFTS ADVERTISED...WIDESPREAD
FOG IS STILL ANTICIPATED OVERNIGHT THROUGH EARLY TOMORROW
MORNING. ONCE THE FOG LIFTS BY MID MORNING...LOW CEILINGS WILL
STILL BE PRESENT AND NEED UNTIL MID DAY TO LIFT TO MVFR LEVELS AND
POSSIBLY SCATTER OUT.

KMSP...REMOVED TEMPO GROUP STARTING OUT AND REPLACED WITH VCSH FOR
THE FIRST FEW HOURS OF THE TAF. LATEST RADAR IMAGERY SHOWS JUST
ONE SMALL SHOWER FORMING ALONG A BOUNDARY ADVANCING SOUTH THROUGH
SCOTT COUNTY. THE AIRFIELD WILL LIKELY REMAIN DRY...BUT CANT
COMPLETELY RULE OUR A ROGUE SHOWER HITTING MSP...HENCE THE VCSH
MENTION. OTHERWISE...FOG EXPECTED OVERNIGHT...WITH BETTER VSBYS
THAN MORE RURAL SITES...AND LOW CLOUDS LIFTING THROUGH THE MORNING
HOURS.

/OUTLOOK FOR KMSP/
SAT...MVFR WITH IFR/+TSRA POSSIBLE. WINDS E AT 10G15 KTS.
SUN...VFR WITH MVFR/TSRA POSSIBLE. WINDS NW 10 KTS.
MON...VFR. WINDS VARIABLE 5 KTS.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...HEAT ADVISORY UNTIL 8 PM CDT THIS EVENING FOR MNZ076-077-082>085-
     091>093.

WI...NONE.
&&

$$

SHORT TERM...JPC
LONG TERM...DWE
AVIATION...SPD






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