Area Forecast Discussion
Issued by NWS Twin Cities, MN

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000
FXUS63 KMPX 182121
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
421 PM CDT MON AUG 18 2014

.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 421 PM CDT MON AUG 18 2014

THERE ARE TWO AREAS OF CONVECTION WE ARE FOCUSED ON THIS AFTERNOON.
THE FIRST IS OVER WEST CENTRAL WISCONSIN IN THE VICINITY OF THE WARM
FRONT. ENOUGH INSTABILITY HAS DEVELOPED AND IS COMBINING WITH MODEST
SHEAR TO GENERATE SOME FEISTIER CELLS. WILL CONTINUE TO WATCH THESE
OVER THE NEXT SEVERAL HOURS AS THEY WILL LIKELY OCCASIONALLY PRODUCE
BORDERLINE SEVERE HAIL.

THE SECOND AREA OF CONCERN IS BACK TO THE WEST ALONG THE COLD FRONT
WHICH ALSO HAS SUPPORT UPSTAIRS FROM A HEALTHY MID LEVEL SHORTWAVE.
TEMPERATURES OVER WEST AND SOUTH CENTRAL MINNESOTA HAVE WARMED INTO
THE MID 80S...AND DEWPOINTS ARE IN THE 60S. THIS AREA IS THEREFORE
PRIMED FOR CONVECTIVE DEVELOPMENT THIS AFTERNOON AND EVENING WITH
MIXED LAYER CAPES EXCEEDING 2000 J/KG AND THE ARRIVAL OF THE
AFOREMENTIONED SHORTWAVE/FRONT SUPPLYING THE NECESSARY
SHEAR/CONVERGENCE. THESE STORMS WILL ALSO HAVE THE POTENTIAL TO
BECOME SEVERE...WITH THE THREATS BEING LARGE HAIL AND DAMAGING
WINDS. WILL ALSO NEED TO MONITOR THE POTENTIAL FOR FLOODING WHERE
THE STORMS TRACK OVER AREAS THAT RECEIVED EXCESSIVE RAINFALL OVER
THE LAST 24 HOURS.

THE TROUGH SHIFTS INTO WISCONSIN BY DAYBREAK TUESDAY. PLENTY OF
RESIDUAL MOISTURE AND LIGHT ENOUGH WINDS SHOULD BE CONDUCIVE TO FOG
DEVELOPMENT AGAIN TONIGHT. ARE NOT EXPECTING AS MUCH IN THE WAY OF
DENSE FOG AS WHAT OCCURRED THIS MORNING...GIVEN WINDS ARE A BIT
HIGHER AND FROM THE NORTHWEST.

SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED TO LINGER GENERALLY
EAST OF THE INTERSTATE 35 CORRIDOR ON TUESDAY...IN CLOSER PROXIMITY
TO THE TROUGH AND ASSOCIATED LIFT. TEMPERATURES WILL THEREFORE BE
COOLER OVER EAST CENTRAL MINNESOTA AND WISCONSIN...WHERE HIGHS ARE
EXPECTED TO TOP OUT IN THE 70S. LOWER 80S WILL BE POSSIBLE OVER
WEST/SOUTH CENTRAL MINNESOTA WHERE A BIT MORE SUN WILL BE
OBSERVED.

.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 421 PM CDT MON AUG 18 2014

IN THE WAKE OF THE SHORT TERM SYSTEM...SURFACE RIDGING WILL RETURN
WITH THE AXIS ALIGNED ACROSS ERN MN AND WRN WI. THE VERY WEAK
WIND FIELD UP TO ABOUT 800 MB WILL FACILITATE EFFICIENT
RADIATIONAL COOLING. IN ADDITION...TEMPERATURES WILL LIKELY FALL
BELOW THE CROSSOVER TEMP BY SEVERAL DEGREES SO FOG SHOULD BE
FAIRLY WIDESPREAD AND POSSIBLY DENSE UNDER THE RIDGE AXIS. FURTHER
SOUTH AND WEST...NAMELY WESTERN AND SOUTHERN MN...RETURN FLOW MAY
BEGIN LATE TUESDAY NIGHT WHICH MAY HAMPER SOME POTENTIAL FOR WIDESPREAD
FOG.

A WARM FRONT WILL LIFT NORTH ACROSS THE PLAINS WEDNESDAY AS
RIDGING BUILDS. A WIDE OPEN GULF OF MEXICO WILL ALLOW PW VALUES OF
2 INCHES TO ADVECT INTO THE REGION LATE WEDNESDAY AND WEDNESDAY
NIGHT. ISENTROPIC UPGLIDE AND A STRENGTHENING 40 TO 50 KT 850 MB
JET WILL BRING STRONG MOISTURE CONVERGENCE FOCUSED OVER ERN SODAK
AND WRN AND SRN MN WEDNESDAY EVENING. EML FROM THE PLAINS SHOULD
ALSO ENHANCE MUCAPE INTO THE 1000-2000 J/KG RANGE OVERNIGHT. IT IS
UNCLEAR ATTM WHETHER THE THUNDERSTORM DEVELOPMENT WEDNESDAY
AFTERNOON OVER ERN SODAK WILL EVOLVE INTO ONE MCS...MULTIPLE
MCS/S...OR A LARGE AREA OF RAIN WITH EMBEDDED THUNDER WEDNESDAY
NIGHT. MID LEVEL WINDS DO NOT APPEAR ALL THAT STRONG...SO A
FORWARD PROPAGATING MCS APPEARS SOMEWHAT UNLIKELY.
NEVERTHELESS...RAISED POPS TO CATEGORICAL OVER CENTRAL
MN...LIKELIES ELSEWHERE FOR INCREASING CONFIDENCE IN SPATIAL AND
TEMPORAL DETAILS OF THE COMPLEX(ES).

THE WARM FRONT SHOULD LIFT NORTH OF THE CWA THURSDAY...WITH THE
ONLY CAVEAT BEING HOW THE OVERNIGHT MCS MAY REINFORCE THE
PREFRONTAL COLD SECTOR. IF THE FRONT DOES MAKE IT
THROUGH...TEMPERATURES WILL BE QUITE WARM AS 925 MB TEMPS RISE
INTO THE MID 20S C. 90 DEGREE TEMPERATURES ARE POSSIBLE OVER SRN
AND ERN MN UNDER THE THERMAL RIDGING. HELD BACK A BIT THURSDAY
BASED ON UNCERTAINTY WITH THE WARM FRONT. CONFIDENCE INCREASES A
BIT WITH TEMPS AND DEW POINTS BY FRIDAY AS A SURFACE CYCLONE
DEVELOPS IN THE PLAINS AND RIDGING BUILDS TO THE EAST. BOUNDARY
LAYER TEMPS WARM A BIT MORE FROM THURSDAY AND IF ONE MIXES AS
FORECAST SOUNDINGS INDICATE...MID 90S WOULD OCCUR. THE QUESTION IS
AGAIN CLOUD COVER AND HOW QUICKLY THE CYCLONE PUSHES THE COLD
FRONT THROUGH. HEAT INDICES OF 95 TO 100 ARE CURRENTLY FORECAST
ACROSS SRN MN WITH DEW POINTS IN THE LOW TO MID 70S. THUNDERSTORM
CHANCES INCREASE AS THE FRONT APPROACHES FRIDAY NIGHT.

COLD FROPA LATE FRIDAY NIGHT OR SATURDAY WILL MARK THE BEGINNING
OF MUCH COOLER PATTERN INTO NEXT WEEK. 850 MB AND 925 MB TEMPS
DROP INTO THE RANGE SUPPORTING HIGHS ONLY IN THE 60S BY MONDAY.
THE FRONT WILL STALL OVER THE CENTRAL PLAINS AND THE UNUSUALLY
TIGHT BAROCLINICITY FOR THIS TIME OF YEAR COULD SPAWN ADDITIONAL
SYSTEMS. CLOUDS AND RAIN NORTH OF THE BOUNDARY WOULD BRING EVEN
COOLER TEMPERATURES THAN CURRENTLY FORECAST...WHICH ARE BASED ON
FULL OR PARTIAL SUNSHINE AND COMPLETE MIXING.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1253 PM CDT MON AUG 18 2014

SITES WILL EXPERIENCE A BRIEF BREAK FROM THE PRECIP AND LOW CLOUDS EARLY
THIS AFTERNOON. THE NEXT SPOKE OF ENERGY WILL SURGE INTO THE AREA
ATTENDANT WITH DAYTIME PEAK HEATING...SO EXPECT SHRA/TS TO
REDEVELOP AROUND 19Z AND EXPAND EASTWARD ACROSS THE AREA UNTIL
EARLY EVE. SHOULD SEE ACTIVITY DIMINISH BY 03Z...WITH THE MAIN
CONCERN BEING FOG AND STRATUS AGAIN. WINDS WILL BE A LITTLE
STRONGER THAN LAST NIGHT AND FROM THE NORTHWEST...SO DO NOT EXPECT
FOG TO GET QUITE AS DENSE AS IT DID. DO HOWEVER STILL EXPECT
IFR/LIFR CIGS/VSBYS TO DEVELOP AND PERSIST THROUGH MUCH OF TUESDAY
MORNING. A FEW SHOWERS MAY DEVELOP AGAIN BY TUESDAY
AFTERNOON...ESPECIALLY OVER WEST CENTRAL WI. SOUTHWEST WINDS
PREVAIL TODAY...THEN SHIFT TO THE NORTHWEST TONIGHT INTO TOMORROW.

KMSP...
ONLY A FEW CU/STRATOCU CLOUDS TO START THE PERIOD...WITH TS/MVFR
CHANCES RETURNING AFTER 22Z. SHOULD SEE ANY SCATTERED SHRA END BY
03Z...WITH MVFR VSBYS AND FOG POSSIBLE AGAIN OVERNIGHT INTO
TUESDAY MORNING. ALSO EXPECT A LOW-END MVFR OR EVEN IFR CIG TO
PERSIST TUESDAY MORNING...WITH SOME IMPROVEMENT/SCATTERING DURING
THE AFTERNOON.

/OUTLOOK FOR KMSP/
WED...VFR. WIND E 5-10 KTS.
THU...VFR. CHC MVFR WITH TSRA. WINDS SE 5-10 KTS BECMG SW.
FRI...VFR. CHC MVFR WITH TSRA. WINDS NE 5-10 KTS.


&&

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

$$

SHORT TERM...LS
LONG TERM...BORGHOFF
AVIATION...LS





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