Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 200830
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
330 AM CDT SAT SEP 20 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 239 AM CDT SAT SEP 20 2014

CURRENT SFC ANALYSIS SHOWS A WMFNT PUSHING INTO SWRN
WI WITH ITS ASSOCIATED TRAILING CDFNT OVER CENTRAL-SWRN MN. WITHIN
THIS WARM SECTOR...BANDS OF RAIN/TSTMS BROKE OUT OVER FAR SRN MN
INTO NRN IA...NOW MOVING INTO FAR SERN MN/SWRN WI/NE IA. THIS LINE
WILL CONTINUE TO PUSH OFF TO THE E AS THE CDFNT SHIFTS ACRS
CENTRAL-SRN MN. THERE WILL NOT BE MUCH OF AN AIRMASS CHANGE WITH
THIS FNT...SO LOWS WILL ONLY DROP TO THE UPR 50S TO MID 60S THIS
MRNG. THE CDFNT WILL ACT TO TEMPORARILY STABILIZE THE ATMOS IN
CONJUNCTION WITH A LONGWAVE TROUGH AXIS ALOFT ALSO SHIFTING TO THE
E. HOWEVER...THE FOCUS WILL THEN TURN TO A SHORTWAVE DISTURBANCE
WHICH SHOWS UP NICELY ON WV IMAGERY THIS MRNG DRIVING SEWD OVER
CENTRAL ALBERTA PROVINCE ON ITS WAY TO NRN MN AND WRN WI BY THIS
EVE. A COMPACT SFC LOW PRES REFLECTION WILL ALSO BE ASSOCIATED WITH
THIS UPR LVL DISTURBANCE...ARRIVING WITHIN A STILL FAIRLY DEEP
MOISTURE COLUMN DUE TO THE CDFNT FOR THIS MORNING FAILING TO REMOVE
MUCH OF THE AMBIENT MOISTURE. MODELS STILL DEPICT AN 80-100 KT UPR
LVL JET MAX MOVING INTO WRN MN BY MIDDAY...HELPING ENHANCE LIFT OVER
NRN AND CENTRAL PORTION OF THE STATE IN ITS EXIT REGION. THE
ACCELERATING STRONG DYNAMICS...ALONG WITH MORE FAVORABLE LAPSE RATES
DUE TO COOLING AIR ARRIVING ALOFT...SHOULD OVERCOME ANY MOISTURE
DEFICIENCIES TO PROMOTE LINEAR TSTM DEVELOPMENT STARTING IN NRN MN
THEN SHIFTING SWD INTO CENTRAL-SRN MN LATER TODAY. STILL SOME MINOR
TIMING ISSUES...BUT THE BULK OF ANY PRECIP ACTIVITY OVER MN WILL
OCCUR IN THE AFTN HOURS FROM W TO E COINCIDENT WITH THE MOVING JET
STREAK ALOFT. THE SEVERE WX NATURE WILL BE LARGE HAIL...GIVEN
PROLONGED ENOUGH UPDRAFTS...AND DAMAGING WINDS...GIVEN THE EXPECTED
MCS DEVELOPMENT OF THE TSTMS. AS THE POTENT SHORTWAVE ALOFT DRIVES
INTO WRN MN...IT WILL SHIFT THE EXPECTED LINE OF TSTMS ACRS THE CWFA
BY THE MID-EVE HOURS...ALLOWING FOR A GRADUAL CLEARING FROM W TO E
THIS EVENING THRU TONIGHT. THERE MAY BE SOME LINGERING SHWRS AFTER
MIDNIGHT IN FAR ERN PORTIONS OF THE WFO MPX CWFA BUT THE BULK OF THE
CWFA SHOULD BE DRY BY THEN. RESIDUAL MILD/MOIST AIR WILL KEEP TEMPS
ABOVE NORMAL THRU TDA WITH HIGHS HITTING THE LOW-MID 70S GENERALLY.
AS THE AFTN-EVE COMPACT LOW PRES SYSTEM BLAZES THRU THE AREA THIS
EVE...THIS WILL BE A MORE EFFECTIVE STARTER OF CAA AS COOLER/DRIER
CANADIAN HIGH PRESSURE DROPS INTO THE REGION AND FLOW ALOFT IS
DECIDEDLY NW. THIS COMBINATION OF CLEARING SKIES AND CAA WILL FORCE
LOW TEMPS TNGT INTO THE UPR 40S AND LWR 50S.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 239 AM CDT SAT SEP 20 2014

SUNDAY MARKS THE BEGINNING OF A MOSTLY DRY AND WARM PATTERN THAT
WILL TAKE US THROUGH NEXT WEEK.

EASTERN MN AND WESTERN WI WILL STILL BE UNDER THE INFLUENCE OF
SHORT WAVE ENERGY ON THE BACKSIDE OF THE SYNOPTIC-SCALE TROUGH
THAT SHOULD BE CENTERED OVER LAKE MICHIGAN BY 12Z SUNDAY. THERE IS
GOOD MODEL CONSENSUS ON THE TIMING AND LOCATION OF THE LONG WAVE
PATTERN. THIS LIKELY MEANS WESTERN WI AND POSSIBLY EASTERN MN WILL
HANG ONTO CLOUD COVER AND LIGHT RAIN SHOWERS BETWEEN 12-18Z
SUNDAY. THE WESTERN FORECAST AREA WILL REMAIN DRY AND EVEN AREAS
IN WEST CENTRAL WI COULD SEE IMPROVEMENT DURING THE AFTERNOON.
HIGH AMPLITUDE TROUGH-RIDGE PATTERN SETS UP MON/TUE IN AREAS TO
OUR WEST. IT WILL CONTINUE TO BE WELL ABOVE NORMAL IN THE WESTERN
CONUS SUNDAY AND MONDAY. THE RIDGE SLIDES EAST ACROSS THE NORTHERN
PLAINS AND UPPER MISSISSIPPI RIVER VALLEY ON TUESDAY. THE LOW
LEVEL JET INCREASES OUT OF THE SOUTHWEST AND WARMER AIR WILL FIND
ITS WAY INTO MN/WI. THE UPPER TROUGH THAT`S FORECAST TO ARRIVE
HERE ON WEDNESDAY IS CURRENTLY JUST KIND OF HANGING OUT OFF THE
COAST OF CALIFORNIA THIS MORNING...CUT OFF FROM THE MAIN JET
CURRENTLY OVERHEAD. THIS LOW GETS KICKED OUT OF THE WEST COAST IN
A COUPLE DAYS AND HEADS THIS WAY AS A MUCH STRONGER TROUGH
ADVANCES ACROSS THE NORTHEAST PACIFIC. WE HAVE CHANCE POPS IN THE
FORECAST TUE-WED...BUT NO REAL STRONG FEELING FOR EXACT TIMING OR
AMOUNTS AT THIS POINT. THESE CUTOFF LOWS ARE ALMOST ALWAYS SLOWER
THAN WHAT THE NUMERICAL GUIDANCE SUGGESTS...BUT AT LEAST THERE IS
A STRONG WAVE IN THE PACIFIC TO DO THE MOVING. OTHERWISE...NEXT
WEEK WILL FEATURE MUCH ABOVE NORMAL TEMPS WITH PLENTY OF MIDDDLE
TO UPPER 70S TO GO AROUND. WOULDN`T BE SURPRISED TO SEE SOME
SITES HIT 80 AT SOME POINT LATE NEXT WEEK.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1100 PM CDT FRI SEP 19 2014

CONVECTION IS NOW EAST AND SOUTH OF THE TAF SITES LATE THIS
EVENING. A GROWING CONCERN OVERNIGHT IS HOW EXPANSIVE STRATUS AND
FOG WILL BECOME THAT HAS FORMED ACROSS PORTIONS OF CENTRAL MN
WHERE SKIES HAVE CLEARED AND WINDS HAVE BECOME LIGHT. THINKING IS
THAT CONDITIONS WILL ACTUALLY IMPROVE BY 09Z AS HIGH LEVEL CLOUDS
INCREASE ACROSS THE AREA ALONG WITH A COLD FRONTAL PASSAGE THAT
WILL BEGIN TO LOWER DEW POINTS. THERE COULD STILL BE SOME MVFR
CEILINGS DEVELOP NORTH AND EAST OF THE TWIN CITIES ON SATURDAY
WITH A VERY NEGATIVE CU RULE. A SECOND AND MUCH STRONGER COLD
FRONT IS SET TO BLAST SE ACROSS THE TAF SITES SATURDAY AFTERNOON.
A LINE OF CONVECTION IS STILL EXPECTED TO BE NEAR KAXN BY
21Z...KMSP AT 00Z AND KEAU BY 03Z. VERY STRONG WIND GUSTS MAY
OCCUR AS THE SHRA AND TSRA MOVE THROUGH. CONTINUED WITH TEMPO TSRA
AND NARROWED THE WINDOW DOWN TO 2 HOURS. WINDS BECOMING WNW NEAR
10 KNOTS OVERNIGHT AND NW 12-15 KNOTS ON SATURDAY. GUSTS WILL
REACH INTO THE 20 TO 25 KNOT RANGE.

KMSP...TEMPORARY BOUTS OF MVFR VSBYS ARE POSSIBLE EARLY THIS
MORNING AS SKY COVER DIMINISHES AND WINDS WEAKEN. INDICATED 6SM BR
BY 08Z THROUGH DAYBREAK. COLD FRONTAL PASSAGE BY DAYBREAK AS WELL
WITH NW WINDS 12-15 KNOTS THROUGH THE DAY. A SECOND AND STRONG
COLD FRONT WILL LIKELY BRING A LINE OF TSRA ACROSS THE AIRFIELD IN
THE 23Z-01Z TIME FRAME. THE STORMS MAY CONTAIN STRONG WIND GUSTS.

/OUTLOOK FOR KMSP/
SUN...VFR. WINDS NW 10-15 KTS.
MON...VFR. WINDS W 5-10 KTS.
TUE...VFR. WINDS SE 5-10 KTS.


&&

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

$$

SHORT TERM...JPC
LONG TERM...CLF
AVIATION...RAH






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