Area Forecast Discussion
Issued by NWS Twin Cities, MN

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000
FXUS63 KMPX 030557
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1257 AM CDT WED JUN 3 2015

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 320 PM CDT TUE JUN 2 2015

CONVECTIVE DEVELOPMENT ASSOCIATED WITH AN ADVANCING AREA OF LOW
PRESSURE OVER THE WESTERN DAKOTAS IS THE PRIMARY FOCUS THROUGH
TOMORROW.

IN THE MEANTIME...GUSTY SOUTHERLY WINDS AND INCREASING HEIGHTS AHEAD
OF THE TROUGH HAVE FACILITATED A WARMING TREND TO ABOVE NORMAL
TEMPERATURES TODAY...WITH MID AFTERNOON TEMPERATURES IN THE 75 TO 80
DEGREE RANGE. A FEW SHOWERS LEFTOVER FROM NOCTURNAL DAKOTAS
CONVECTION HAVE HELD TOGETHER ENOUGH TO GENERATE A FEW LIGHT RADAR
RETURNS OVER WEST CENTRAL MINNESOTA THIS AFTERNOON. REALLY DO NOT
EXPECT TO SEE MUCH MORE THAN THAT UNTIL DEVELOPING CONVECTION IN THE
DAKOTAS /CLOSER TO THE SFC LOW...MORE SO IN NORTH DAKOTA NORTH OF
THE MID LEVEL CAPPING INVERSION/...SPREADS EASTWARD INTO WEST
CENTRAL MN LATER THIS EVENING. MEANWHILE...ANOTHER AREA OF
CONVECTION WILL LIKELY DEVELOP OVER SOUTH DAKOTA THIS EVENING AS A
SHORTWAVE PRESSES IN AND THE LOW LEVEL JET STRENGTHENS. THIS
SECONDARY ACTIVITY IS THEN EXPECTED TO MOVE INTO THE FORECAST AREA
AFTER 09Z...AND SPREAD EASTWARD DURING THE MORNING HOURS.

ON WEDNESDAY AFTERNOON...THE COLD FRONT WILL BE MOVING ACROSS THE
AREA. HOWEVER...MODELS DO FAVOR STRATUS CLOUD DEVELOPMENT DURING THE
MORNING HOURS...AND WITH THE POTENTIAL FOR CONVECTIVE DEBRIS FROM
THE DAKOTAS ACTIVITY...MAY HAVE A TOUGH TIME DESTABILIZING. DEEP
LAYER SHEAR IS ALSO VERY MARGINAL...SO AT THIS TIME THE LIKELIHOOD
OF ORGANIZED SEVERE STORMS IS LOW IN OUR FORECAST AREA.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 320 PM CDT TUE JUN 2 2015

THE FIRST PART OF THE EXTENDED PERIOD... WEDNESDAY NIGHT THRU
FRIDAY WILL BE IMPACTED BY HOW FAR SOUTH THE FRONTAL BOUNDARY SAGS
TO THE SOUTH OF OUR CWA. THE SECOND HALF OF THE EXTENDED
PERIOD...SATURDAY THRU TUESDAY...WILL BE RELATED TO ANOTHER
FRONTAL BOUNDARY AND UPPER LONG WAVE TROUGH MOVING ACROSS CANADA
AND INTO THE GREAT LAKES/NORTHEAST.

FIRST...THE MEAN UPPER LEVEL FLOW WILL HOLD FROM THE WEST...AND
WEST-SOUTHWEST FROM WEDNESDAY NIGHT...THRU FRIDAY. ALTHOUGH THIS
IS A RELATIVELY FAST FLOW...BOTH THE GFS/EC HAVE HELD OR EVEN
SLOWED THE FRONTAL BOUNDARY POSITION WEDNESDAY NIGHT WHICH MAY
LEAD TO HOLDING ONTO THE PRECIPITATION LONGER INTO THE EVENING
THAN EXPECTED. BUT...WITH THE FAST FLOW...YOU WOULD EXPECT A
FASTER SOLUTION AND QUICKLY MOVING OUT THE FRONTAL BOUNDARY AND
ASSOCIATED PRECIPITATION FIELD WITH IT. I DO LIKE THE EC/GEM
SOLUTIONS WHICH KEEPS THE BULK OF THE PRECIPITATION FIELD EAST/SE
OF OUR CWA AFT 00Z AS THE ANTICIPATED SHRTWV EMBEDDED IN THIS
FASTER FLOW...MOVES EAST OF OUR AREA. THE SECOND CONCERN IS
WHETHER HIGH PRESSURE BUILDING SOUTHWARD THURSDAY/FRIDAY WILL
ALLOW FOR SOME DRIER AIR TO FILTER IN. THE GFS IS WETTER AND
FURTHER NORTH THEN THE EC/GEM WHICH SEEMS UNREALISTIC DUE TO THE
DRIER EAST/NE FLOW DEVELOPING. HOWEVER...KEPT SLIGHT CHC AS FAR
NORTH AS THE TWIN CITIES BASED ON SOME DIFFERENCES IN THE WIND
FIELDS.

THE SECOND HALF OF THE EXTENDED PERIOD WILL BE RELATED TO THE
EVOLUTION OF THE UPPER LOW DEVELOPING IN THE SW CONUS...AND THE
UPPER RIDGE BUILDING OVER TEXAS. THIS TYPE OF PATTERN WILL LEAD
TOWARD WARMER AND SLIGHTLY DRIER CONDITIONS IF THE UPPER RIDGE
BUILDS FURTHER TO THE NORTH ACROSS THE UPPER MIDWEST. WILL
CONTINUE WITH THE BLENDED SCENARIO...BUT THE BEST SOLUTION IS TO
HOLD ONTO CHC POPS STARTING SATURDAY/SUNDAY AS THE MEAN FLOW FROM
BOTH THE EC/GFS BECOMES MORE NW DUE TO A STRONGER SHRTWV MOVING SE
ACROSS CENTRAL CANADA LATE IN THE WEEKEND.

THERE REMAINS NO REAL WARM WEATHER IN TERMS OF HIGHS IN THE 80S OR
EVEN 90S BASED ON THE UPPER FLOW AND MEAN ENSEMBLES 50H HEIGHTS
PAST THE MIDDLE OF NEXT WEEK. THE KEY FOR ANY SUBSTANTIAL WARM UP
WILL OCCUR ONCE THE LONG WAVE TROUGH THAT HAS BEEN PERSISTENT OVER
EASTERN CANADA...SLOWLY BREAKS DOWN...OR A LONG WAVE TROUGH BEGINS
TO TAKE OVER THE WESTERN CONUS.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1256 AM CDT WED JUN 3 2015

FEATURE OF CONCERN THIS TAF PERIOD IS THE MCV THAT HAS DEVELOPED
ALONG THE NEB/SD BORDER. MAJORITY OF LEAD MCS OVER NEB SHOULD DIVE
SOUTH INTO IOWA...BUT LIKE THE IDEA OF THE 3&4Z RUNS OF THE HRRR
WITH A BAND OF SHOWERS WORKING ACROSS MN AND INTO WI DURING THE
MORNING HOURS WITH THE ARRIVAL ELEVATED INSTABILITY PLUME. AFTER
THAT...ALSO LIKE THE IDEA OF THE HRRR/NMM/ARW AND A COUPLE OF THE
HOPWRF MEMBERS OF SHOWERS/STORM EXPANDING IN WRN MN AROUND 18Z AS
THE MCV ARRIVES. IN THE TAFS...MENTIONED A SHRA OR VCSH FOR WHEN
MORNING ACTIVITY COULD IMPACT TAFS...WHILE VCTS WAS USED IN THE
AFTERNOON TO ACCOUNT FOR POTENTIAL MCV PRECIPITATION. ALSO TRIED
TO BACK TRACK SOME ON THE MVFR POTENTIAL IN THE MORNING. RIGHT
NOW...SUB VFR CIGS ARE CONFINED TO THE NW OF THE FRONT AND THINK
WE NEED TO START GETTING INTO THAT POST FRONTAL ENVIRONMENT BEFORE
MVFR OR LOWER CIGS BECOME A BIG CONCERN...BUT THE FRONT WILL NOT
GET INTO THE NW MPX AREA UNTIL THE AFTERNOON.

KMSP...CONFIDENCE IN PRECIP FORECAST IS LOW...HENCE THE LONG
PERIODS OF VCSH/VCTS. AFRAID THE HRRR MAY BE OVERDONE ON HOW MUCH
PRECIP WE SEE THIS MORNING...BUT THE HRRR HAS SUPPORT FROM A
COUPLE OF HOPWRF MEMBERS FOR SOME MORNING SHOWERS...SO LEFT THAT
MENTION IN. AFTERNOON HAS LOWER CONFIDENCE AS WELL AS IT IS STILL
TO EARLY TO PIN DOWN EXACTLY WHERE/WHEN SHRA/TSRA WILL DEVELOP
LATE THIS MORNING/EARLY AFTERNOON BENEATH THE MCV. TONIGHT...WE
WILL HAVE A BAGGY PRESSURE GRADIENT WITH A MOIST BOUNDARY
LAYER...SO THAT IS LIKELY WHEN THE THREAT FOR MVFR OR LOWER CIGS
WILL BE GREATEST...PER SREF PROBABILITIES.

/OUTLOOK FOR KMSP/
THU...MVFR CIG/VIS IN MORNING. WIND NNE 5 KTS.
FRI...VFR. WIND E 10 KTS.
SAT...VFR. WIND SE 10 KTS.

&&

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

$$

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


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