Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 231813
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
113 PM CDT SAT MAY 23 2015

.UPDATE...

UPDATED TO INCLUDE 18Z AVIATION DISCUSSION BELOW.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 258 AM CDT SAT MAY 23 2015

THE UPPER LEVEL TROUGH CENTERED OVER THE FOUR CORNERS REGION THIS
MORNING IS THE FEATURE OF CONCERN FOR THE PERIOD. IT IS STILL ON
TRACK TO LIFT NORTHEAST TODAY AND TONIGHT...BUT ITS SPEED IN DOING
SO LOOKS A TAD SLOWER AT THIS TIME. SO...THE PRIMARY CHANGES TO
THE SHORT TERM FORECAST WAS TO JUST DELAY THE POPS A FEW HOURS
ACROSS THE AREA.

THE LATEST HI-RES GUIDANCE INDICATES A NARROW BAND OF RAINFALL
PUSHING NORTH INTO SOUTHWESTERN MN THIS MORNING...THANKS TO LOW
LEVEL WARM AIR ADVECTION AHEAD OF THE APPROACHING TROUGH.  FORCING
THOUGH WILL NOT BE IMPRESSIVE AND VERY DRY AIR UNDER THE LCL TODAY
WILL HAMPER THE ABILITY OF THIS BAND TO PRODUCE MEASURABLE
PRECIPITATION.  THIS BAND MAY BE PRIMARILY VIRGA...SO DID REDUCE
POPS INTO THE SLIGHT CHANCE CATEGORY.  MOST OF THE FA WILL REMAIN
DRY TODAY...BUT MOSTLY CLOUDY UNDER THE MID AND UPPER LEVEL MOISTURE
FEED FROM THE SOUTHWEST...SO TEMPERATURES WILL BE SLIGHTLY COOLER
THAN YESTERDAY...BUT STILL EXPECT HIGHS AROUND 70 FOR MOST OF THE
AREA.

FOR TONIGHT...SLOWED DOWN THE ONSET OF THE PRECIP AS GENERAL
CONSENSUS OF THE MODELS AGREE ON A SLOWER PROGRESSION INTO OUR
AREA. IN FACT...THE 00Z RUN OF THE ECMWF NOW KEEPS EASTERN MN AND
WESTERN WI COMPLETELY DRY THROUGH 12Z SUNDAY...AND THE ARW-EAST
MATCHED UP WELL WITH THE ECMWF. CURRENT FORECAST HAS TRENDED THAT
DIRECTION AS THE MAIN PRECIP SHIELD IS NOT EXPECTED TO IMPACT MOST
OF THE AREA UNTIL DURING THE DAY ON SUNDAY.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 258 AM CDT SAT MAY 23 2015

MORE WIDESPREAD PRECIPITATION COMES SUNDAY AS A DEEP H5 LOW PRES
CENTER OVER THE CENTRAL ROCKIES CONTRIBUTES TO A DEVELOPING SFC
LOW PRES CENTER OVER THE W-CENTRAL PLAINS. A LARGE PLUME OF WRN
GOMEX MOISTURE WILL CONTINUE TO SURGE INTO THE REGION ON THE WRN
SIDE OF A LARGE SERN CONUS H5 HIGH PRES DOME...SO THE SFC AND
ALOFT LOW PRES COMBINATION DRIFTING NEWD WILL HAVE PLENTY OF
MOISTURE WITH WHICH TO PRODUCE PERIODS OF SHWRS/T-STORMS OVER THE
REGION FROM MID-TO-LATE DAY SUNDAY THRU MON NIGHT. THE SFC LOW
LOOKS TO TAKE A TRACK THAT WILL BRING IT FROM ERN CO/WRN KS SUN
AFTN INTO CENTRAL MN BY DAYBREAK MON MRNG WHILE THE KICKER UPR LVL
LOW WILL COINCIDENTALLY SHIFT NEWD INTO THE ERN DAKOTAS. THE
TILTED ASPECT OF THE LOW WITHIN A DEEPLY MOIST ENVIRONMENT WILL
PROVIDE PLENTY OF ISENTROPIC LIFT ON ITS LEADING EDGE TO PRODUCE
FAIRLY WIDESPREAD RAIN SUN NIGHT INTO MON. THIS ADDITIONAL
MOISTURE INTO THE ATMOS...EVEN NEAR THE SFC AS EVIDENCED BY
FORECAST DEWPOINTS INTO THE LWR 60S...MAY ADD SOME FUEL TO THE
POTENTIAL OF STRONG/SEVERE STORMS ON MON. EXPANSIVE CLOUD COVER
AND MEAGER LAPSE RATES MAY WELL PUT A DAMPER ON SUCH POTENTIAL BUT
BETWEEN SUNDAY AND MONDAY...MONDAY LOOKS TO BE THE BETTER DAY FOR
ANY STRONG/SEVERE STORMS. HOWEVER...WITH PWATS AROUND 1.50 INCHES
AND A PROLONGED NATURE OF THIS SYSTEM...ISOLD POCKETS/PERIODS OF
HEAVY RAIN CANNOT BE RULED OUT FOR SUN NIGHT INTO MON.

THE SFC LOW AND UPR LVL LOW PRES FEATURES WILL PULL AWAY TO NE ON
TUE...ALLOWING FOR A DIMINISHING OF PRECIP COVERAGE AND INTENSITY
TUE THRU WED...WITH SOME BONA FIDE DRY TIME LIKELY FOR MUCH OF THE
AREA DURING THIS TIME. THE WEDNESDAY-FRIDAY TIMEFRAME HAS A MUCH
HIGHER DEGREE OF UNCERTAINTY DUE TO THE UPPER LEVEL FLOW BECOMING
MORE ZONAL AND A SFC PATTERN THAT HAS LESS DEFINITION. SEVERAL
UPR LVL SHORTWAVES PASSING THRU THE REGION FROM TIME TO TIME WILL
BE MOST RESPONSIBLE FOR SHWR/TSTM DEVELOPMENT DURING THE LATTER
HALF OF THE WEEK...SO HAVE CAPPED POPS IN THE CHC CATEGORY TO
ALLOW FOR BETTER MODEL AGREEMENT BEFORE LOCKING ON A PERIOD WORTHY
OF A LIKELY POP.

AS FOR TEMPERATURES...THE THEME OF LITTLE DAY-TO-DAY VARIATION
STILL HOLDS TRUE. IT DOES LOOK THAT WEDNESDAY WILL HAVE THE
HIGHEST TEMPERATURES THROUGHOUT THE UPCOMING WEEK...WITH HIGHS
HITTING THE UPR 70S. THIS DOES MAKE SENSE WITH A SLY SFC FLOW
RESUMING AFTER THE DEPARTURE OF THE EARLY WEEK STORM SYSTEM AND A
MIX OF SUN AND CLOUDS EXPECTED FOR WED. OTHERWISE...TEMPS WILL
GENERALLY RANGE FROM THE MID 60S TO THE MID 70S...STILL RATHER
COMFORTABLE FOR LATE MAY. LOWS WILL MAINLY REMAIN IN THE 50S.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 100 PM CDT SAT MAY 23 2015

EVEN WITH THESE LIGHT SHOWERS AND SPRINKLES MOVING THROUGH THE
AREA THIS AFTERNOON...LITTLE TO IMPACTS TO CEILINGS AND VISIBILITY
SHOULD BE EXPECTED. VFR SHOULD PERSIST INTO AT LEAST THE FIRST
HALF OF THE NIGHT. THE WINDS HAVE BEEN TRICKY TODAY...VARIABLE AT
MANY LOCATIONS. IN GENERAL...WE EXPECT A LIGHT E-SE FLOW TO
DEVELOP AT MOST SITES THIS AFTERNOON/EVENING. MANY SITES ARE
ALREADY THERE...BUT EASTERN MN AND WESTERN WI HAS BEEN SLOW TO
MAKE THE CHANGE OVER. TOMORROW LOOKS RAINY AND WE COULD START TO
SEE MORE SITES PICK UP MVRF CONDITIONS BY TOMORROW LATE MORNING
INTO THE AFTERNOON. THUNDER IS POSSIBLE TOMORROW...BUT WILL NOT
BE WIDESPREAD.

KMSP...

THE WIND DIRECTION HAS BEEN THE CHALLENGE OF THE TAF TODAY. WINDS
ARE TRICKY IN SITUATIONS LIKE THIS WHERE THE AIRPORTS SHOW
DIVERGING WINDS AT THE SURFACE. IN THESE CASES...THE WINDS ARE
OFTEN LIGHT AND HAVE LOTS OF VARIABILITY IN DIRECTION. THE LAST 30
MINUTES HAVE SHOWN MORE OF A TENDENCY OF A NORTHEAST DIRECTION.
SO OUR BEST EDUCATED GUESS AT THIS POINT IS FOR A N-NE-E-SE
TRANSITION TO THE WINDS OVER THE NEXT 6-12 HOURS AND IN GENERAL
THE SPEED SHOULD BE UNDER 7-8KTS.

/OUTLOOK FOR KMSP/
MON...VFR. SCT SHRA/TSRA WITH MVFR OR LOWER CONDITIONS. WINDS S
10 KTS.
TUE...VFR. CHC SHRA/-TSRA. WINDS SW 10 KTS.

&&

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

$$

UPDATE...JPC
SHORT TERM...SPD
LONG TERM...JPC
AVIATION...CLF


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