Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 261829
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
129 PM CDT SUN JUL 26 2015

.UPDATE...

HAVE MADE A COUPLE OF TWEAKS TO THE GRIDS TODAY. WE HAVE A REMNANT
H7 LOW FROM CONVECTION LAST NIGHT THAT IS NOW STUCK BENEATH A
BUILDING RIDGE. THIS HAS KEPT MID CLOUDS GOING ALONG THE MN/WI
BORDER AND RAP/NAM SHOW THAT CONTINUING THROUGH THE DAY. THEREFOR
INCREASED CLOUD COVER AND DECREASED HIGHS A FEW DEGREES ALONG THE
MN/WI WHERE...WHERE UPPER 80S TO NEAR 90 IS NOW UNLIKELY. ALSO
TRIMMED BACK POPS QUITE A BIT...LEAVING A SMALL AREA OF ISO
THUNDER AROUND SE MN. RAP SHOWS A RIBBON OF 1500-2000 J/KG OF
SBCAPE DEVELOPING. SEVERAL CAMS ALSO SHOW SOME ISO ACTIVITY
DEVELOPING HERE AS WELL...SO FELT THERE WAS AT LEAST SOME
JUSTIFICATION FOR LEAVING POPS IN DOWN THERE.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 333 AM CDT SUN JUL 26 2015

THE MAIN SHORT TERM CONCERN IS THE POTENTIAL FOR DIURNALLY DRIVEN
SHOWER AND THUNDERSTORM DEVELOPMENT TODAY.

THE AREA OF SHOWERS AND THUNDERSTORMS WILL CONTINUE TO TRACK
EASTWARD ACROSS THE SOUTHERN THIRD OF MINNESOTA EARLY THIS
MORNING. IN THE WAKE OF SAID ACTIVITY...HI-RES MODELS SHOW
700 MB TEMPS/HEIGHTS BUILDING ACROSS SOUTHWEST MN...WITH AN H7
TEMP CIRCA +11C OR GREATER DEVELOPING GENERALLY ALONG AND
WEST/SOUTH OF THE MN RIVER VALLEY BY 18Z. THE MAJORITY OF CAMS
MODELS INDICATE SPOTTY CONVECTION DEVELOPING THIS AFTERNOON ALONG
THE EASTERN PERIPHERY OF THIS CAPPING INVERSION. WHILE THERE IS
NOT ANY SORT OF WELL-DEFINED FOCUSING MECHANISM TO SPARK SHOWERS
AND THUNDERSTORMS OTHER THAN THE INSTABILITY THAT IS PROGGED TO
DEVELOP WITH SFC DEWPOINTS IN THE 70S AND FAINT MIDLEVEL ENERGY
OVERHEAD...FEEL A 20 POP IS WARRANTED.

ANY CONVECTION WOULD COME TO AN END AROUND SUNSET...WITH A MUGGY
SUMMER NIGHT AHEAD...AS LOW TEMPS HOLD UP IN THE UPPER 60S TO
LOWER 70S WITH DEWPOINTS NOT TOO FAR BELOW THAT.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 333 AM CDT SUN JUL 26 2015

THE EXTENDED PERIOD CAN BE CHARACTERIZED AS HOT/HUMID AND UNSETTLED
AT THE BEGINNING...THEN TURNING COOLER AND DRIER BY THE END OF THE
WEEK.

AN ABNORMALLY STRONG UPPER LOW IS FORECAST TO DEEPEN AND MOVE ACROSS
THE NORTHERN ROCKIES AND EASTWARD ALONG THE CANADIAN BORDER FROM THE
NORTHERN PLAINS AND UPPER MIDWEST BY WEDNESDAY.

AHEAD OF THIS SYSTEM...SOUTHERLY FLOW WILL KEEP CONDS VERY
WARM AND HUMID WITH HEAT INDICES BOTH MONDAY/TUESDAY AFTN IN THE
MID TO UPPER 90S. I WOULD NOT BE SURPRISED IF THE URBAN AREA OF THE
TWIN CITIES METRO AREA WOULD GET A HEAT ADVISORY FOR BOTH MONDAY AND
TUESDAY BASED ON THESE CONDS. THE ONLY QUESTION IS WHETHER MORE
CLOUD COVER WILL INHIBIT FULL SUNSHINE AND LOWER AFTN HIGHS.

THERE IS ENOUGH INSTABILITY AND A STRONG SW FLOW ALOFT AHEAD OF THE
UPPER LOW MONDAY TO WARRANT ISOLD TSRA IN EC MN/WC WI...ESPECIALLY
CONSIDERING MID LEVEL LAPSE RATES ARND 7.0 TO 7.5C.

THE MAIN FOCUS FOR ACTIVE WX AND THE POTENTIAL OF SVR WX WILL BEGIN
LATE MONDAY NIGHT AS MOISTURE ADVECTION...ALONG THE INCREASING LLJ
SURGES NORTHWARD ACROSS THE UPPER MIDWEST. HEIGHT FALLS WITH THE
UPPER LOW AND A STRENGTHENING SFC LOW IN THE DAKOTAS SHOULD WARRANT
THIS SIGNIFICANT LLJ AND ASSOCIATED MOISTURE ADVECTION. THIS WILL
LEAD TO A BROAD AREA OF CONVECTION DEVELOPING NEAR MPX CWA. STEEP
LAPSE RATES/AMPLE INSTABILITY ALONG THE STRONG LLJ SHOULD BE ENOUGH
TO WARRANT SVR POTENTIAL. AT THIS TIME...SPC IS NOT HIGHLIGHTING
OUR REGION...WITH MAINLY A MARGINAL RISK OF SVR WX. A BETTER CHC OF
SVR WX IS LIKELY TUESDAY AFTN AHEAD OF THE COLD FRONT. THE PROBLEM
WITH TUESDAY IS A VERY STRONG CAP DEVELOPING DURING THE DAYTIME WITH
70H TEMPS RISING TO NEAR 14C. IT MAYBE LATE IN THE EVENING BEFORE
THIS CAP BEGINS TO BREAK WHICH LEADS TO MORE SVR WX SE OF MPX CWA.
THE MAIN PVA ASSOCIATED WITH THE UPPER LOW IS NOT FORECAST TO MOVE
INTO MN UNTIL AFT TUESDAY EVENING. SO...THE STRONG CAP COULD
PRECLUDE AN ACTIVE TUESDAY EVENING IN MN...AND THE MAIN FOCUS IN
WI/IA DURING THE LATE EVENING ONCE THE CAP BREAKS.

PAST TUESDAY NIGHT...THE ABNORMALLY STRONG UPPER LOW WILL MOVE NORTH
OF THE GREAT LAKES...BRING DRIER WX AND COOLER TEMPS FOR THE SECOND
HALF OF THE WORK WEEK.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1219 PM CDT SUN JUL 26 2015

MAIN QUESTION THIS PERIOD IS WHETHER OR NOT WE SEE LOW STRATUS/FOG
DEVELOP TONIGHT TO THE NORTH OF A WEAK WARM FRONT THAT WILL BE
LIFTING NORTH OUT OF IOWA. WE WILL HAVE A VERY MOIST...LIGHT EAST
FLOW IN THE LOW LEVELS ALL NIGHT...WHICH IS A FAVORABLE DIRECTION
FOR GETTING LOW CLOUDS...BUT WITH NOTHING OUT THERE NOW...WILL
SIDE WITH CLIMATOLOGY AND MENTION NOTHING MORE THAN SOME MVFR BR.
SREF PROBS FOR CIGS UNDER 3K FT WOULD SAY BEST SHOT AT SEEING
STRATUS WOULD BE ALONG AND SOUTH OF THE MN RIVER...IMPLYING RWF
HAS THE GREATEST CHANCE AT SEEING STRATUS TONIGHT. ALSO HAVE HIGH
CONFIDENCE IN THIS TAF PERIOD BEING DRY AT ALL TERMINALS...WITH
TSRA CHANCES NOT STARTING TO RAMP UP UNTIL AFTER 3Z TUESDAY.

KMSP...GFSLAMP HAS BEEN BACKING AWAY FROM FOG/STRATUS TONIGHT SO
HAVE KEPT MSP VFR THROUGHOUT...THOUGH THE EXPECTED ESE WIND
THROUGH TONIGHT IS A FAVORABLE DIRECTION FOR GETTING FOG/LOW
STRATUS. WE LOOK TO BE CAPPED MONDAY AFTERNOON...SO NOT EXPECTING
ANYTHING UNTIL STORMS SHOW UP MONDAY NIGHT...WHICH MODELS THIS
MORNING SHOW MOVING INTO MSP BETWEEN 9Z AND 12Z TUESDAY.

/OUTLOOK FOR KMSP/
TUE...IFR/MVFR IN TSRA EARLY THEN VFR. WINDS S BCMG SW 10-15 KTS.
WED...VFR. WINDS W 15-20G30KTS.
THU...VFR. WINDS W 10-15 KTS.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&

$$

SHORT TERM...LS
LONG TERM...JLT
AVIATION...MPG



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