Area Forecast Discussion
Issued by NWS Twin Cities, MN

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000
FXUS63 KMPX 250151
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
851 PM CDT THU APR 24 2014

.UPDATE...
ISSUED AT 845 PM CDT THU APR 24 2014

UPDATED TO INCLUDE 00Z AVIATION DISCUSSION BELOW.

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 355 PM CDT THU APR 24 2014

RAIN WAS DIMINISHING ACROSS THE EASTERN HALF OF THE FA AT MID
AFTERNOON AS A MID LEVEL LOW EXITED INTO NORTHERN WISCONSIN. A BAND
OF SHOWERS IN THE WAKE OF THIS LOW WAS ASSOCIATED WITH AN OCCLUDED
FRONT. THE SHOWERS WILL PUSH EAST OF THE TWIN CITIES BY LATE THIS
AFTERNOON WITH THE FRONT MOVING THROUGH THE FA BY LATE THIS EVENING.
SCATTERED SHOWERS HAVE DEVELOPED OVER PORTIONS OF THE EASTERN
DAKOTAS THIS AFTERNOON UNDER THE UPPER LOW. A FEW THUNDERSTORMS
CAN/T BE RULED OUT IN WEST CENTRAL MN INTO EARLY THIS EVENING WITH A
FEW HUNDRED J/KG OF ML MUCAPE ALONG WITH SLIGHTLY NEGATIVE LI/S.

OVERNIGHT...THE MAIN CONCERN IS HOW MUCH FOG DEVELOPS AND IF IT DOES
WILL IT BE DENSE. WE CERTAINLY HAVE THE LOW LEVEL MOISTURE AND
THE FORECAST HYDROLAPSE FOR MUCH OF CENTRAL AND SOUTHERN MN IS
FAVORABLE. HOWEVER...THERE IS UNCERTAINTY ON HOW LONG SUBSTANTIAL
WIND WILL PREVAIL DURING THE NIGHT AS THE SURFACE RIDGE AXIS MOVES
IN LATE. FOLLOWED THE HOPWRF ON DEVELOPING FOG TONIGHT ACROSS MUCH
OF THE FA WHILE MOST SHORT TERM SOLUTIONS INDICATED VERY LITTLE FOG.
IT WOULD SEEM THE BEST PLACE FOR THE POTENTIAL OF DENSE FOG
OVERNIGHT IS FROM CENTRAL MN ON SOUTH TO WEST OF THE TWIN CITIES.

FRIDAY IS SHAPING UP TO BE A PRETTY NICE DAY. NORTHWEST WINDS WILL
INCREASE TO 10 TO 15 MPH DURING THE DAY. ABUNDANT SUNSHINE IS
FORECAST ACROSS THE MN RIVER VALLEY WITH HIGH TEMPERATURES FROM
MIX-DOWN INDICATING MIDDLE TO UPPER 60S. IT WILL BE COOLER TO THE
NORTHEAST (LOWER 50S TO LOWER 60S) WHERE MORE CLOUDINESS WILL
PREVAIL.

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 355 PM CDT THU APR 24 2014

THE LONG TERM STILL LOOKS TO BE DOMINATED BY A CLOSED/CUT OFF UPPER
LOW THAT WILL BRING ABOUT A PROLONGED PERIOD OF CLOUDY...RAINY...AND
COOL WEATHER TO END APRIL.

THE EVOLUTION OF THE UPPER AIR PATTERN IN THE EXTENDED IS QUITE
INTERESTING AS A COUPLE OF REX BLOCKS BECOME MAJOR PLAYERS FOR THE
WEATHER PATTERN ACROSS NOAM. THE FIRST WILL DEVELOP THIS WEEKEND
OVER THE NORTH ATLANTIC. THIS CAUSES EVERYTHING UPSTREAM TO
AMPLIFY...WITH A SHARP RIDGE DEVELOPING ACROSS CENTRAL NOAM AS DEEP
TROUGHS FLANK IT ON THE WEST AND EAST COASTS OF THE CONTINENT. AT
THE BEGINNING OF NEXT WEEK...THE REX BLOCK SHIFTS WEST TO CENTRAL
NOAM...AS THE RIDGE THIS WEEKEND BUILDS NORTH TO WRN HUDSON BAY. AS
THIS HAPPENS...THE WRN TROUGH WILL ABSORB SOME ENERGY FROM THE ERN
TROUGH AS A CUT OFF LOW DEVELOPS OVER THE CENTRAL CONUS...DUE SOUTH
OF THE UPPER HIGH IN CANADA. THIS IS THE PATTERN THAT WILL STICK
WITH US MUCH OF NEXT WEEK. THE ECMWF CONTINUES TO OFFER THE MOST
INTERESTING DEMISE OF THE CENTRAL NOAM REX BLOCK...WITH THE BLOCK
CONTINUING ITS TREK WEST NEXT WEEKEND...SETTING UP OVER ALASKA.

THE LONG TERM WILL START OFF DRY AT THE VERY LEAST...BUT SATURDAY
WILL FEATURE BOTH INCREASING CLOUDS AND INCREASING EAST WINDS AS A
SFC LOW BEGINS TO DEEPEN NEAR THE CO/KS/NE BORDER IN RESPONSE TO THE
NEGATIVELY TILTED TROUGH COMING OUT OF THE SRN ROCKIES. AS THIS IS
HAPPENING...OUR INCREASING ERLY LOW LEVEL FLOW WILL BE PULLING DOWN
VERY DRY AIR FROM A HUDSON HIGH...SO CONTINUED KEEP THINGS DRY
DURING THE DAY SATURDAY AS THE ATMO BELOW H7 LOOKS TO BE SETUP
PERFECTLY FOR VIRGA. INSTEAD...HAVE LIKELY POPS COMING IN SOUTH OF
THE MN RIVER SATURDAY NIGHT AS THE LOW TO THE SW DRIFTS TOWARD
CENTRAL NEB...POINTING A GOOD SURGE OF MOISTURE TRANSPORT AND WAA
OUR DIRECTION. AFTER THAT...GET USED TO THE CLOUDS AND RAIN. THOUGH
MODEL DIFFERENCES DO EXIST WITH HOW FAR NORTH THE HIGH/LOW CENTERS
OF THE REX BLOCK SETUP...THE GFS/ECMWF/GEM ALL PAINT PLENTY OF QPF
ACROSS THE MPX CWA MONDAY THROUGH THURSDAY. THOUGH IT OBVIOUSLY WILL
NOT BE RAINING THE ENTIRE...WHEN DOING 12 HOUR LONG POP GROUPS...YOU
END UP WITH A PROLONGED PERIOD OF CHANCE POPS FOR MUCH OF NEXT WEEK.
RUN TOTAL QPFS FROM THE GEM/GFS/ECMWF ALL PAINT 2 TO 4 INCHES OF
RAIN ACROSS THE MPX AREA FOR NEXT WEEK...SO WILL CERTAINLY BE
SETTING A GOOD BASE TO THE 2014 GROWING SEASON.

FOR P-TYPE...THE VAST MAJORITY OF THE PRECIP WILL COME IN THE FORM
OF RAIN...BUT THERE WILL BE THE POTENTIAL /MAINLY NORTH OF I-94/ TO
MIX IN SOME WET SNOWFLAKES DURING THE EARLY MORNING HOURS DEPENDING
ON HOW MUCH WE CAN COOL DOWN IN THE OVERNIGHT HOURS. THOUGH NO
SEVERE WEATHER IS EXPECTED /WILL BE PLENTY OF THAT TO THE
SOUTH/...BEST LI/S ARE NEGATIVE ALONG AND SOUTH OF THE MN RIVER
VALLEY SUNDAY AND MONDAY MORE OR LESS...SO WILL LIKELY HEAR A FEW
RUMBLES OF THUNDER AS WE GET INTO THE PROLONGED ISENTROPIC/FGEN
FORCED PRECIP EVENT.

UNFORTUNATELY...WHAT ALL OF THIS CLOUD COVER...PRECIP...AND EAST TO
NORTH WINDS MEANS FOR US IS THAT TEMPERATURES FROM SATURDAY THROUGH
THURSDAY OF NEXT WEEK WILL BE RUNNING A GOOD 10 TO 15 DEGREES BELOW
NORMAL. THIS WILL ENSURE THAT APRIL CONTINUES OUR STREAK OF BELOW
NORMAL MONTHS THAT STARTED IN NOVEMBER AND WILL ALSO REQUIRE THE
TEMPERATURE IN MAY TO BE WELL ABOVE NORMAL TO KEEP THE SPRING
/MAR-MAY/ FROM BEING BELOW NORMAL AS WELL.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 845 PM CDT THU APR 24 2014

LOW CLOUDS WILL IMPACT ALL SITES OVERNIGHT WITH MVFR CONDS
EXPECTED AND IFR CONDS LIKELY. TIMING THE LOW CLOUDS WILL BE
PROBLEMATIC...AS BOTH WI SITES HAVE ALREADY DROPPED INTO IFR WHILE
IFR CONDS OVER WRN-CENTRAL MN WILL BE LATER AND POSSIBLY INTO ERN
MN. AM NOT LOOKING FOR MUCH IN THE WAY OF PRECIP AS A WEAK SWATH
OF SHWRS ENTERING SW AND W MN EARLIER THIS EVENING CONTINUES TO
SHOW DIMINISHING SIGNS. STILL...TO ACCOUNT FOR THIS PRECIP...HAVE
ONLY INCLUDED 6SM -SHRA...THUS IMPLYING INTERMITTENT SHWRS WITH NO
VSBY REDUCTION DUE TO THEM. AS WINDS DIMINISH OVERNIGHT...LOW
STRATUS AND/OR FOG WILL BECOME AN ISSUE...ESPECIALLY OVER WRN MN
AND WRN WI...POTENTIALLY DOWN TO IFR /NOT SO MUCH IN CENTRAL-ERN
MN/. CONDS GRADUALLY IMPROVE LATE TMRW MRNG INTO TMRW AFTN TO VFR.
LGT/VRBL WINDS WILL PERSIST THRU THE OVERNIGHT HRS...THEN WINDS
INCREASE OUT OF THE NW DURG THE DAY TMRW...POTENTIALLY TO
15G25KT...BEFORE VEERING TO N LATE TMRW AFTN WITH SPEEDS CLOSER TO
10 KT.

KMSP...MVFR TO START BUT AM CONCERNED WITH THE WWD PROGRESS OF LOW
CLOUDS AND FOG OVER WRN WI. AM THINKING THE SHORTWAVE
TROF...INDICATED BY THE WEAKENING SHWRS...OVER W-CENTRAL MN WILL
CONTINUE TO SHIFT E AND HOLD UP THE IFR CONDS OVER WI FROM
IMPACTING MSP. THAT SAID...BEHIND THE WAVE...WHEN WINDS DROP
OFF...MVFR FOG LOOKS TO DEVELOP OVER THE AREA. NOT CONFIDENT ON
IFR CONDS ATTM...AND MOS GUIDANCE ONLY INDICATES A SMALL WINDOW OF
SUCH...SO HAVE LEFT IT OUT ATTM BUT WILL MONITOR AND INCLUDE IF
NEEDED. CONDS IMPROVE NICELY AFTER DAYBREAK TMRW AND REMAIN VFR
THRU THE DAY TMRW INTO TMRW NIGHT. AS FOR WINDS...HAVE INCLUDED
GUSTS TO NEAR 20 KT AS DEEPER MIXING AND MOS GUIDANCE INDICATES
FREQUENT ENOUGH GUSTS TO MENTION.

/OUTLOOK FOR KMSP/
SAT...VFR. NE WINDS 10-15 KTS.
SUN...MAINLY VFR. MVFR CONDS POSSIBLE IN -RA. E WINDS 15-25 KTS.
MON...MVFR/IFR -RA BR. E WINDS 15-25 KTS.

&&

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

$$

UPDATE...JPC
SHORT TERM...TRH
LONG TERM...MPG
AVIATION...JPC






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