Area Forecast Discussion
Issued by NWS Twin Cities, MN

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000
FXUS63 KMPX 230359
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1059 PM CDT FRI AUG 22 2014

.UPDATE...
ISSUED AT 1047 PM CDT FRI AUG 22 2014

UPDATED TO INCLUDE 06Z AVIATION DISCUSSION BELOW.

&&

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 350 PM CDT FRI AUG 22 2014

INITIAL SHORT TERM CONCERN IS THE REDEVELOPMENT AND COVERAGE OF
FOG LATER TONIGHT. CLOUD DECK REMAINS TRAPPED UNDER STRONG
INVERSION OVER EASTERN MN/NORTHWEST WISCONSIN. EXPECT MUCH OF THIS
AREA OF THICKER CLOUD COVER TO DISSIPATE/ERODE FURTHER ALONG THE
ITS OUTERMOST PERIPHERY. HOWEVER...LOOKS LIKE A SMALL AREA OF
CLOUD COVER WILL REMAIN TO THE NORTHEAST. GIVEN THE LATE BREAK UP
OF CLOUDS AND COOLER TEMPERATURES...COULD SEE FOG DEVELOP AGAIN
BEFORE MIDNIGHT IN THE EAST. WINDS ARE EXPECTED TO REMAIN
LIGHT...SO STRATUS AND FOG IS ONCE AGAIN ANTICIPATED OVER THE
NORTHEAST PORTION OF THE CWA. FURTHER SOUTHWEST...HIGH CLOUDS WILL
MOVE IN LATER TONIGHT...AND THIS MAY HELP PRECLUDE DENSE FOG FROM
FORMING. WILL HAVE TO MONITOR INTO THE EVENING. TEMPERATURES
SHOULD COOL BACK TO MAINLY THE MID/UPPER 60S.

LATER TONIGHT...MODELS HAVE TRENDED SLOWER WITH THE FORCING MOVING
IN. WILL MAINTAIN A SMALL CHANCE TO THE SOUTHWEST FOR NOW. THE
MAIN FORCING MOVES LONG THE DAKOTAS/MN BORDER LATE
MORNING/AFTERNOON. WE STILL MAY SEE A BAND OF WAA SHOWERS/ISOLATED
THUNDER LIFT NORTHEAST ACROSS EASTERN MN...MAINLY SATURDAY
AFTERNOON. THE MAIN SHOW SHOULD HOLD OFF UNTIL THE COMING EVENING.
SEVERE WEATHER POTENTIAL INCREASES DURING THE DAY AS WELL WITH
OVERALL DEEP LAYER SHEAR INCREASING AHEAD OF THE MAIN TROUGH LATE
SATURDAY AFTERNOON OVER THE WEST. LARGE HAIL/DAMAGING WINDS
POSSIBLE OVER THE WEST AS THE WARM FRONT LIFTS NORTHEAST TOWARD
SOUTHWEST MN LATER IN THE AFTERNOON.

.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 350 PM CDT FRI AUG 22 2014

THE LONGER RANGE OF THE FORECAST LOOKS TO BE MARKED BY OCCASIONAL
SHOWER AND THUNDERSTORM CHANCES OVER THE WEEKEND...HOT
TEMPERATURES SUNDAY...THEN COOL AND DRY WEATHER FOR MUCH OF THE
UPCOMING WEEK.

AT THE START OF THE LONG TERM FORECAST PERIOD...A SURFACE LOW
CIRCA 1000MB IS PROGGED TO BE LOCATED OVER THE DAKOTAS. MODEL
SOLUTIONS ALL FEATURE THIS SYSTEM...ALTHOUGH AMPLITUDE AND SPATIAL
DIFFERENCES ARE QUITE APPARENT. THIS LEADS TO LOW CONFIDENCE WITH
HOW FAR EAST THE SHOWERS AND THUNDERSTORMS WILL REACH ON SATURDAY
NIGHT...BUT MUCH HIGHER CONFIDENCE THAT WEST CENTRAL MINNESOTA
WILL EXPERIENCE CONVECTION /IN CLOSER PROXIMITY TO THE LOW AND
FORCING/ADVECTION/.

ON SUNDAY...THE LOW LIFTS TO MANITOBA/ONTARIO...WHILE THE
ASSOCIATED COLD FRONT PASSES ACROSS THE AREA. AHEAD OF THE
FRONT...THE THERMAL RIDGE NOSES INTO EAST CENTRAL MINNESOTA AND
WEST CENTRAL WISCONSIN. EXPECT HIGHS TO SNEAK INTO THE LOWER
90S...WHICH MEANS A HEAT ADVISORY COULD BE NEEDED FOR A PORTION
OF THE AREA...POTENTIALLY INCLUDING HENNEPIN AND RAMSEY COUNTIES.
SCATTERED SHOWERS AND THUNDERSTORMS WILL REMAIN A POSSIBILITY FOR
MUCH OF THE AREA ON SUNDAY...SO WILL HAVE TO MONITOR HOW RESIDUAL
CLOUDS/PRECIPITATION IMPACT HIGH TEMPS.

FOR MONDAY...AN OVERALL DRY DAY IS EXPECTED AS WEAK
RIDGING/SUBSIDENCE WORKS INTO THE AREA. THE BREAK IN PRECIPITATION
WILL BE SHORT LIVED HOWEVER...AS AN INVERTED TROUGH NOSES INTO
THE UPPER MIDWEST ON MONDAY NIGHT. MODELS ARE NOT IN GREAT
AGREEMENT WITH THIS SYSTEM EITHER...BUT THERE IS RATHER HIGH
CONFIDENCE THAT SHOWERS AND THUNDERSTORMS WILL BLOSSOM FROM
SOUTHERN MN ACROSS EAST CENTRAL MINNESOTA AND WEST CENTRAL
WISCONSIN ON MONDAY EVENING. THE BOUNDARY THEN SAGS JUST SOUTH OF
THE AREA THROUGH THE MIDDLE OF THE WEEK...AND FOSTERS SHOWER AND
THUNDERSTORM CHANCES THROUGH WEDNESDAY...ESPECIALLY ACROSS
SOUTHERN MINNESOTA. THE LOCATION WHERE THE FRONT STALLS IS STILL
UNCERTAIN...BUT HEAVY RAINFALL COULD BECOME A CONCERN WITH THE
POTENTIAL FOR MULTIPLE ROUNDS OF PRECIPITATION TO POTENTIALLY
TRACK OVER THE SAME AREA.

TEMPERATURES WILL BE NOTABLY COOLER FROM TUESDAY THROUGH
THURSDAY...WITH HIGHS IN THE UPPER 60S TO MID 70S.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1047 PM CDT FRI AUG 22 2014

LINGERING MVFR CEILINGS OVER NERN PORTIONS OF THE COVERAGE AREA
SLOWLY RECEDED NE THIS EVE BUT STILL HELD OVER KRNH WHILE THE
REMAINING TAF SITES HELD IN VFR. BY LATE EVENING...THE PLENTIFUL
LOW LEVEL MOISTURE AND LIGHT WINDS WILL AGAIN COMBINE TO PRODUCE
IFR-OR-LOWER CONDITIONS...MAINLY DUE TO CEILINGS BUT ALSO
POTENTIALLY FOG FOR THE USUAL SUSPECTS /A.K.A. KSTC...KRNH AND
KEAU/. HAVE MAINTAINED THIS THINKING IN THE 00Z TAFS WITH THE
WORST CONDITIONS MAINLY BETWEEN 08Z-14Z SAT. CONDS THEN LOOK TO
SLOWLY IMPROVE THRU THE MRNG HOURS. ONE OTHER COMPLICATION IS THE
POTENTIAL DEVELOPMENT OF SCATTERED TO NUMEROUS SHOWERS/TSTMS OVER
ERN SD/ERN NE/WRN IA THAT WILL SPREAD INTO SWRN MN BY AROUND
DAYBREAK THRU LATE MRNG. THIS WOULD AFFECT KRWF-KAXN-KSTC LATE
MRNG INTO THE EARLY AFTN. TOO EARLY ATTM TO DETERMINE FLIGHT COND
DETERIORATION BUT WILL FOR NOW SHOW PREVAILING PRECIP AT THE WRN
TAF SITES.

BY LATE EVENING...THE PLENTIFUL
LOW LEVEL MOISTURE AND LIGHT WINDS WILL AGAIN COMBINE TO PRODUCE
IFR- OR-LOWER CONDITIONS...MAINLY DUE TO CEILINGS BUT ALSO
POTENTIALLY FOG FOR THE USUAL SUSPECTS /A.K.A. KSTC...KRNH AND
KEAU/. HAVE MAINTAINED THIS THINKING IN THE 00Z TAFS WITH THE
WORST CONDITIONS MAINLY BETWEEN 08Z-14Z SAT. CONDS THEN LOOK TO
SLOWLY IMPROVE THRU THE MRNG HOURS. ONE OTHER COMPLICATION IS THE
POTENTIAL DEVELOPMENT OF SCATTERED TO NUMEROUS SHOWERS/TSTMS OVER
ERN SD/ERN NE/WRN IA THAT WILL SPREAD INTO SWRN MN BY AROUND
DAYBREAK THRU LATE MRNG. THIS WOULD AFFECT KRWF-KAXN-KSTC LATE
MRNG INTO THE EARLY AFTN. TOO EARLY ATTM TO DETERMINE FLIGHT COND
DETERIORATION BUT WILL FOR NOW SHOW PREVAILING PRECIP AT THE WRN
TAF SITES.

KMSP...CONDS BOUNCED BETWEEN VFR AND MVFR FOR MUCH OF THE
EVENING...FINALLY HOLDING AT VFR COMING INTO THE 06Z
INITIALIZATION TIME. AM STILL LOOKING FOR CONDS TO DROP TO
SUB-1700 FT CEILINGS LATER TONIGHT AND HOLDING THERE THRU THE
EARLY MRNG HRS. IFR CONDS THEN SETTLE IN CLOSE TO DAYBREAK BUT AM
NOT XPCTG MUCH OF A VSBY RESTRICTION FROM VFR...JUST INTO MVFR.
THE IFR CIGS WILL THEN LIKELY LAST THRU LATE MRNG TO AROUND
MIDDAY...WITH VFR CONDS EXPECTED TMRW AFTN. DEGRADED CONDS
EXPECTED AGAIN SAT EVENING...BUT AM ONLY ADVERTISING MVFR CIGS
ATTM AND THIS DEGRADATION MAY BE LATER THAN ADVERTISED.

/OUTLOOK FOR KMSP/
SUN...VFR. MVFR/TSRA POSSIBLE EVENING/OVERNIGHT. WINDS S10G20 KTS.
MON...VFR. WINDS W 5-10 KTS.
TUE...MAINLY VFR. CHC MVFR IN TSRA. WINDS NE 5-10 KTS.

&&

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

$$

UPDATE...JPC
SHORT TERM...DWE
LONG TERM...LS
AVIATION...JPC





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