000
FXUS63 KMPX 130928
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
428 AM CDT MON MAY 13 2013

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 426 AM CDT MON MAY 13 2013

FROST AND FREEZE CONDITIONS WELL UNDERWAY EARLY THIS MORNING ACROSS
THE WI CWA WITH HIGH PRESSURE OVERHEAD. TEMPERATURES NEAR FREEZING
STRETCH ALL THE WAY WEST TO KSTC. THE HIGH WILL GIVE WAY TODAY TO AN
ADVANCING WARM FRONT... CURRENTLY LOCATED OVER THE WESTERN DAKOTAS.
SHORT TERM MODEL FORECASTS ARE OVERDONE ON PRECIPITATION THIS
MORNING JUST AHEAD OF THE WARM FRONT. OBSERVATIONS INDICATE MID
LEVEL CLOUDS WITH BASES ABOVE 10K. SURFACE DEW POINT FORECASTS ARE
ALSO NEARLY 10 DEGREES TOO HIGH IN THE DAKOTAS AS WELL. THIS IS A
PROBLEM WE HAVE NOTED FOR SEVERAL DAYS NOW. THIS DOES NOT BODE WELL
FOR THE DAY AHEAD. WE CONTINUED TO REFINE THE DEW POINT FORECAST FOR
TODAY WITH THE AFTERNOON MINIMUM HUMIDITY FALLING INTO THE 25 TO 35
PERCENT RANGE ACROSS THE FA. THE LOW END HUMIDITY VALUES ARE IN THE
MN RIVER VALLEY. CONTINUED TO FOLLOW THE SREF POPS BUT RESTRICTED
ANY MENTION OF SLIGHT CHANCE POPS OR HIGHER TO 3 HOURLY
PROBABILITIES OF 40 PERCENT OR GREATER FOR MORE THAN A HUNDREDTH OF
AN INCH. THE HIGH TEMPERATURE FORECAST TODAY IS A LITTLE PROBLEMATIC
DUE TO THE INCOMING CLOUDS AND PRECIP CHANCES. MIX DOWN TOOL FROM
VARIOUS MODEL SOLUTIONS POINTED TO A MUCH COOLER FORECAST FOR THE
EASTERN HALF OF THE FA. BLENDED THE MIX DOWN WITH CONSALL AND
OFFICIAL FOR THE DAY AHEAD.

PRECIPITATION CHANCES WILL END EARLY THIS EVENING IN OUR FAR
EASTERN WI COUNTIES. A MILD NIGHT IN STORE WITH LOWS IN THE 40S AND
50S. THE NEXT CONCERN IS A POTENTIAL CONVECTIVE COMPLEX FORMING OVER
NORTH DAKOTA DURING THE NIGHT WITH SOME SHOWERS PERHAPS REACHING OUR
NW CWA BEFORE DAYBREAK TUESDAY PER THE NMM WRF. WITH THE UNCERTAINTY
OF THIS FEATURE... KEPT POPS OUT FOR NOW WITH THE LONG TERM
FORECASTER ADDING SOME FOR TUESDAY MORNING.

.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 426 AM CDT MON MAY 13 2013

TUESDAY THROUGH SUNDAY...THERE ARE TWO MAIN ITEMS OF INTEREST IN THE
EXTENDED PERIOD. THE FIRST IS THE POTENTIAL FOR RECORD BREAKING
HEAT ON TUESDAY...WHICH MAY BE FOLLOWED BY A FEW STRONGER
THUNDERSTORMS BY THE EARLY EVENING. THE SECOND ITEM IS THE
TRANSITION TO A WETTER PATTERN TOWARDS THE WEEKEND AS SOUTHWEST
FLOW  DEVELOPS ACROSS THE REGION AHEAD OF THE NEXT UPPER LEVEL
TROUGH. WITH REGARDS TO THE HOT WEATHER ON TUESDAY...THERE IS
INCREASING EVIDENCE THAT THE MID LEVEL CLOUDS MAY DAMPER AN ATTEMPT
AT WIDESPREAD 90S ACROSS THE REGION. AS ALLUDED TO EARLIER...HAVE
ADDED SOME SLIGHT CHANCE POPS ACROSS THE FAR NORTHWESTERN CWA
TUESDAY MORNING. BOTH THE GFS AND NAM PLACE THE NOSE OF THE H925 LOW
LEVEL JET NEAR THE SD/ND/MN BORDER. THE GFS 13.00 IS THE MOST
AGGRESSIVE WITH THE SOUTHERN EXTENT OF THE PRECIP...BUT BOTH THE
SREF...AND ECMWF GENERATE QPF ACROSS THE NORTHWESTERN CWA. DEBRIS
CLOUDS FROM ANY CONVECTION THAT DOES FORM WOULD HINDER TUESDAY
TEMPERATURES. IN FACT...BOTH THE GFS AND NAM BUFR SOUNDINGS SHOW MID
LEVEL MOISTURE WITHIN THE 12-15KFT LEVEL...AND THE NAM IS NEARLY
SATURATED DURING THE PEAK HEATING HOURS. DESPITE THIS CONCERNING
CAVEAT...ONE CAN NOT IGNORE THE TIMING OF THE H850 THERMAL
RIDGE...WHICH BRINGS 20 TO 24C TEMPS ACROSS THE SOUTHERN HALF OF THE
CWA DURING THE AFTERNOON HOURS. SO...GIVEN THE CONFLICTING SOLUTIONS
DESCRIBED ABOVE...DID NOT MAKE A DRASTIC CHANGE TO
TEMPERATURES...BUT LOWERED THEM A DEGREE OR TWO. UNFORTUNATELY...THE
TWO MOST PROBABLE SOLUTIONS LIE ON OPPOSITE ENDS OF THE
SPECTRUM...BEING CLEAR SKIES AND MID 90S...OR HAZY SUNSHINE AND
UPPER 80S. ALSO...AS WE NEAR TUESDAY EVENING SOME OF THE SHORTRANGE
CONVECTIVE ALLOWING MODELS ARE SHOWING DEVELOPMENT ALONG THE MN/WI
BORDER. WILL HAVE TO CONTINUE TO WATCH THIS THREAT...SINCE MLCAPE
VALUES OF 2000J/KG TOGETHER WITH AMPLE DEEP LAYER SHEAR WOULD
SUPPORT SEVERE STORMS. HOWEVER CONVECTIVE INITIATION WILL BE
HAMPERED BY THE STRONG CAPPING THAT IS EXPECTED TO BE IN PLACE ALONG
AND AND AHEAD OF THE COLD FRONT.

LOOKING AHEAD....THE COLD FRONT WILL PASS THROUGH THE REGION AND
STALL OUT ACROSS IOWA. THIS WILL BRING DRY WEATHER...LIGHT
WINDS...AND SEASONABLE TEMPS FOR WEDNESDAY AND THURSDAY AS THE UPPER
MISSISSIPPI RIVER VALLEY REGION ENJOYS WEAK SUBSIDENCE BENEATH A
SLIGHTLY ANTICYCLONICLY CURVED UPPER LEVEL JET. BY FRIDAY...BOTH THE
GFS AND ECMWF SHOW A +130KT JET AT 300MB CRASHING ONSHORE OVER
NORTHERN CALIFORNIA. AS THIS JET CARVES OUT AN UPPER LEVEL
TROUGH...LOW SOUTHERLY FLOW DOWNSTREAM WILL DRAW UP MOISTURE FROM
THE GULF ACROSS THE CENTRAL CONUS AND LIFT THE FRONTAL BOUNDARY
NORTHWARD AS A WARM FRONT. THE GFS REMAINS FASTER AND STRONGER
THAN THE ECMWF WITH THIS UPPER LEVEL TROUGH AND ASSOCIATED
SURFACE LOW...BUT CONTINUE WITH LIKELY POPS FOR THE WEEKEND...AND
WILL CONTINUE TO EVALUATE THE SEVERE POTENTIAL AS THE MODELS COME
INTO BETTER AGREEMENT WITH THE TIMING AND LOCATION OF THE
SYNOPTIC/MESOSCALE FEATURES.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1145 PM CDT SUN MAY 12 2013

VFR AT ALL TERMINALS THROUGH TMRW EVE DESPITE THE ARRIVAL OF A
WMFNT ACRS THE REGION. SKIES MAINLY CLEAR THIS EVENING WILL
STEADILY FILL IN FROM THE UPPER LEVELS AND DESCEND DURG THE EARLY
MRNG HOURS AND THROUGH DAYBREAK. CEILINGS LOOK TO DROP AS LOW AS
5-6 KFT BUT AM NOT EXPECTING ANYTHING LOWER. IN FACT...LOWER
LEVELS OF THE ATMOS LOOK TO REMAIN QUITE DRY...SO MUCH IN FACT
THAT PRECIP WILL BE HARD TO COME BY. THEREFORE...HAVE OPTED TO
REMOVE VCSH MENTION SINCE ANY PRECIP THAT WOULD OCCUR WOULD BE
VERY LIGHT AND OPERATIONALLY INSIGNIFICANT. THAT SAID...THE BEST
CHCS FOR PRECIP WOULD BE OVER THE WI TERMINALS WHILE THE MN
TERMINALS ARE EXPECTED TO REMAIN DRY. WINDS WILL BE SOMEWHAT
TRICKY AS THE TIGHTER PRES GRADIENT WILL MAKE FOR A STRONG JUMP IN
WIND SPEEDS TMRW AFTN. SPEEDS WILL INCRS TO ARND 15G25 KT.
DIRECTIONS WILL BE A BIT PROBLEMATIC TO PIN DOWN BUT MAINLY FROM
THE SSE AND SE WITH A SLIGHT SHIFT TO SW TMRW EVENING.

KMSP...HAVE KEPT CONDS AS VFR THROUGHOUT THIS TAF SET AND REMOVED
MENTION OF PRECIP. HIGH CLOUDS ACRS THE AREA WILL STEADILY FILL IN
AND LOWER AS A WMFNT APPROACHES. CEILINGS WILL EVENTUALLY DROP TO
ARND 5 KFT BUT ARE NOT EXPECTED TO GO ANY LOWER...AND THIS WILL BE
BY MIDDAY. HAVE ALSO REMOVED ANY MENTION OF PRECIP SINCE THERE ARE
STILL PLENTY OF MODEL DISCREPANCIES AS TO WHETHER PRECIP WOULD
DEVELOP. PLUS...WITH THE LOWER ATMOS CONTINUING TO RUN DRY...
TRYING TO GET MEASURABLE PRECIP IS PROBLEMATIC AT BEST. THEREFORE
HAVE OPTED TO REMOVE PRECIP MENTION AT MSP /WHICH MATCHES THE REST
OF THE TERMINALS/. SKIES THEN GRADUALLY CLEAR OUT TMRW EVENING
INTO TMRW NIGHT. WINDS WILL EVENTUALLY SETTLE ON S BY DAYBREAK AND
REMAIN AS SUCH THROUGH THE TMRW MRNG. SPEEDS INCREASE TO NEAR 15
KT BY LATE AFTN THEN SETTLE BACK DOWN AFTER DARK.

/OUTLOOK FOR KMSP/
MON NIGHT...VFR. WINDS S 5-10 KT.
TUE...VFR. WINDS SSW 15G20KT.
WED...VFR. WINDS NW 10KT.
THU...VFR. WINDS W 5 KT.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...FIRE WEATHER WATCH FROM TUESDAY AFTERNOON THROUGH TUESDAY
     EVENING FOR MNZ041>045-047>070-073>077-082>085-091>093.

WI...FROST ADVISORY UNTIL 7 AM CDT THIS MORNING FOR WIZ023-024-026.

     FREEZE WARNING UNTIL 7 AM CDT THIS MORNING FOR WIZ025-027-028.

&&

$$

SHORT TERM...RAH
LONG TERM...JRB
AVIATION...JPC