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000
FXUS63 KMPX 181217
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
717 AM CDT SAT MAY 18 2013

.SHORT TERM...(THIS AFTERNOON THROUGH SUNDAY)
ISSUED AT 348 AM CDT SAT MAY 18 2013

TODAY-TONIGHT...BROAD-SCALE RIDGE AXIS JUST E OF THE AREA THIS
MRNG...AND WILL CONTINUE TO SHIFT E WHILE A LARGE BROAD-SCALE
TROUGH SHIFTS E THROUGH THE 4-CORNERS REGION. THOUGH OVERALL
RIDGING HAS SHIFTED E...MINOR BUBBLE RIDGES WITHIN THE DEVELOPING
SW FLOW WILL PREVENT FAIRLY WIDESPREAD PRECIPITATION FROM
DEVELOPING DURG THE DAY TDA. HOWEVER...THAT DOES NOT RULE OUT
ISOLD TO SCATTERED CONVECTION FROM THIS MRNG THROUGH THE DAY TDA.
HAVE ALREADY SEEN A HANDFUL OF SEVERE TSTM WRNGS...INCLUDING SOME
VERIFYING WITH HAIL AS LARGE AS 1.5 INCHES. STORM INTENSITY WILL
GENERALLY STAY ON THE TAME SIDE OF SEVERE THRU MUCH OF THE DAY TDA
WHILE CONDITIONS RAMP UP FOR THE POTENTIAL FOR ISOLD SEVERE TSTMS
LATER THIS EVE AND TNGT. ONE LOW PRES CENTER IDENTIFIED OVER THE
WRN DAKOTAS THIS MRNG WILL WORK IN TANDEM WITH ANOTHER LOW PRES
CENTER OVER WRN NE/KS. AS THE NRN LOW SHIFTS NE...IT WILL HELP
DRAG A WMFNT NE THRU SRN AND CENTRAL MN. THIS WILL NOT ONLY ALLOW
A SURGE OF WARM AIR INTO LOWER MN...PUSHING HIGH TEMPS INTO THE
LOW-MID 80S...BUT ALSO MAINTAIN DEWPOINTS INTO THE 60S. THEN...AS
THE UPPER RIDGE SHIFTS FURTHER TO THE E...MORE PRONOUNCED
MERIDIONAL FLOW WITH LOWERING HEIGHTS WILL ENHANCE LIFT. STEEP
LAPSE RATES ALONG WITH A TONGUE OF MUCH HIGHER INSTABILITY WILL
SURGE INTO WRN MN TNGT...HELPING ENHANCE THE COVERAGE AND
INTENSITY OF TSTMS TNGT. SPC MAINTAINS A SLGT RISK OF SEVERE TSTMS
IN ITS SWODY1...BUT THE TIMING IS STILL A LITTLE UNCERTAIN.
HOWEVER...LOOKING AT THE EVOLUTION OF THE TROUGH AND THE
MAINTENANCE OF RIDGING THRU THE FIRST HALF OF THE DAY...WILL
HIGHLIGHT THIS EVE THRU TNGT AS THE PERIOD WHERE SEVERE TSTMS LOOK
TO OCCUR. MAIN HAZARDS WOULD BE LARGE HAIL AND DMGG WINDS...WITH
ISOLD TORNADOES AS A SECONDARY HAZARD SINCE CONDS ARE LESS
FAVORABLE FOR TORNADOES.

.LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY)
ISSUED AT 348 AM CDT SAT MAY 18 2013

THE MORE SIGNFICANT THREAT FOR SEVERE WEATHER AFFECTS THE REGION
SUNDAY AND SUNDAY NIGHT. SOUTHERLY FLOW WILL BE IN PLACE ACROSS
THE AREA AS THE UPPER LEVEL TROUGH DIGS INTO THE SOUTHERN AND
CENTRAL PLAINS. THE SURFACE CYCLONE IS FORECAST TO DEEPEN AS IT
MOVES TOWARD NORTHEAST NEBRASKA BY SUNDAY EVENING. WILL LIKELY SEE
ACTIVITY WANE FROM THE SATURDAY NIGHT CONVECTION OVER THE CWA INTO
SUNDAY MORNING. WITH THE UNSTABLE AIRMASS IN PLACE..REDEVELOPMENT
MAY OCCUR QUICKLY DURING THE DAY. THE FOCUS SHOULD SHIFT WEST
AGAIN IN THE AFTERNOON ALONG THE MAIN SURFACE BOUNDARY NEARER THE
NEBRASKA LOW. A MORE SIGNIFICANT WAVE LIFTS NORTHEAST SUNDAY NIGHT
AS THE UPPER LOW PIVOTS SLOWLY EAST. FORECAST SOUNDING FOR MSP
INDICATES AROUND 2000 J/KG CAPE WITH STEEP MID LEVEL LAPSE RATES
7.5-8 C/KM. 0-6 KM SHEAR VALUES INCREASE TO 35 TO 45 KTS DURING
THE EVENING AS THE WAVE ROTATES NORTHEAST. HAIL AND DAMAGING WINDS
WILL BE THE MAIN THREATS...BUT WILL HAVE TO MONITOR LOCATION OF
SURFACE FRONT AND OCCLUDING LOW LATER INTO THE EVENING FOR ANY
POSSIBLE TORNADO THREAT. MCS DEVELOPMENT WILL LIKELY OCCUR INTO
SOUTHERN MN...WITH HEAVY RAIN ALSO POSSIBLE AS PWAT IS FORECAST TO
EXCEED 1.6 INCHES.

THE OCCLUDED SYSTEM IS FORECAST TO SAG SLOWLY TO THE SOUTHEAST
MONDAY INTO TUESDAY. WILL LIKELY STILL MAINTAIN A THUNDER THREAT
THROUGH THIS PERIOD. COULD SEE SOME STRONG STORMS YET IN THE
EASTERN CWA (MAINLY WISCONSIN) FOR MONDAY AFTERNOON. THIS WILL ALL
DEPEND ON HOW MUCH DAYTIME HEATING AND DESTABILIZATION CAN TAKE
PLACE. AGAIN HEAVY RAIN WILL BE POSSIBLE...WITH WIDESPREAD 1 TO 2
INCHES FORECASTED FROM SUNDAY THROUGH MONDAY NIGHT.

TEMPERATURES WILL COOL BACK TO BELOW NORMAL READINGS TUESDAY
THROUGH THURSDAY...WITH EXTENSIVE CLOUD COVER REMAINING IN THE
AREA. WARMER AND DRIER CONDITIONS SHOULD FOLLOW THEREAFTER AS THE
UPPER LOW EXITS THE AREA.  UPPER LEVEL HEIGHTS/RIDGING ALOFT
DEVELOPS AND THIS SHOULD EXTEND INTO AT LEAST THE FIRST HALF OF
NEXT WEEKEND.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 650 AM CDT SAT MAY 18 2013

TRICKY TAF SET THIS MORNING DUE TO THE TIMING OF PRECIP INTO AND
OUT OF EACH TERMINAL...INCLUDING TSTM TIMING/DURATION...SO PLENTY
OF RADAR MONITORING WILL BE NECESSARY. SFC WMFNT OVER SWRN MN WILL
SLOWLY LIFT N AND E TDA...NUDGING THE PRECIP SHIELD SLOWLY NE WITH
IT. STILL DEALING WITH PLENTY OF CONVECTION THIS MORNING THAT HAS
BEEN HITTING THE MN TERMINALS THIS MRNG...AND WILL LIKELY BE
HITTING THE WI TERMINALS LATER THIS MRNG INTO THE EARLY AFTN HRS.
AS TSTMS IMPACT THE TERMINALS...WILL SEE VSBY DROP INTO MVFR AND
LIKELY IFR RANGES WHILE CEILINGS HIT THE MVFR RANGE /NOT EXPECTING
IFR CEILINGS WITH TSTMS/. MORNING BANDS OF PRECIP LOOK TO EXIT THE
TERMINALS BETWEEN 16Z-18Z...THEN A PROLONGED BREAK THROUGH THE
REST OF THE DAYLIGHT HOURS WILL BE UPON ALL SITES. A CDFNT WILL
BEGIN TO APPROACH FROM THE W TNGT. AHEAD OF THIS CDFNT...
ADDITIONAL SHWRS/TSTMS WILL SHIFT INTO THE REGION FROM THE W. HAVE
TIMED IT INTO THE WRN TAF SITES LATE THIS EVE...TRANSITIONING EWD
THROUGH THE EARLY MRNG HRS ON SUNDAY.

KMSP...SEVERAL ROUNDS OF RA/TSRA THIS MRNG AT INITIALIZATION TIME
BUT DIFFICULT TRYING TO PIN DOWN THE ENDING TIME AS SEVERAL BANDS
HAVE FORMED WEST OF MSP AND ARE DRIVING E. ATTM...BEST TIMING PUTS
A BREAK BETWEEN 14Z-16Z...WITH THE PRECIP HOLDING OFF UNTIL LATE
TNGT. COULD SEE A FEW SHWRS MOVE ACRS LATE THIS MRNG INTO EARLY
AFTN...BUT AT THAT POINT THE WMFNT SHOULD BE N OF MSP...HELPING
EMPHASIZE A BREAK IN THE PRECIP. TNGT...AS A CDFNT APPROACHES...
ADDITIONAL RAIN/TSTMS WILL DEVELOP OVER THE AREA. COND WILL LIKELY
DROP TO MVFR WITH CEILIGNS AND POSSIBLY IFR WITH VSBY. WILL
MONITOR RADAR TRENDS AND ISSUE AMENDMENTS AS NECESSARY.

/OUTLOOK FOR KMSP/
SUN...VFR/MVFR CIGS. CHC SHRA/TSRA WITH IFR. S-SE WINDS 8-12 KTS.
MON...VFR/MVFR CIGS. CHC SHRA/TSRA WITH IFR. S WIND 10-15 KTS.
TUE...VFR/MVFR CIGS. CHC SHRA/TSRA WITH IFR. E-NE WIND 5 KTS.

&&

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

$$

SHORT TERM...JPC
LONG TERM...DWE
AVIATION...JPC