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000
FXUS63 KMPX 132020
AFDMPX

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

.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 315 PM CDT MON MAY 13 2013

MAIN CONCERNS IN THE SHORT TERM REVOLVE AROUND FIRE WEATHER CONCERNS
BOTH THIS AFTERNOON AND ESPECIALLY FOR TUESDAY. THERE IS ALSO A
SMALL OUTSIDE CHANCE FOR THUNDERSTORMS LATE TUESDAY AFTERNOON...BUT
THAT THREAT STILL LOOKS QUITE MINIMAL THANKS TO DRY AIR AND A STRONG
CAP. THOUGH IF ANYTHING WERE TO GO...GIVEN DEGREE OF SHEAR AND
INSTABILITY...IT WOULD BE SEVERE WITH LARGE HAIL AND WIND BEING THE
THREATS.

WARM FRONT THIS AFTERNOON RAPIDLY APPROACHING WRN MN. HAD A NARROW
BAND OF SHOWERS DEVELOP OVER MN THIS MORNING WITHIN STRONG WAA
REGIME AROUND H85 THAT IS NOW PUSHING INTO WRN WI. THESE SHOWERS ARE
MOVING EAST AT ABOUT 30 MPH AND SHOULD BY OUT OF THE MPX CWA BY
AROUND 00Z. VERY DRY AIR IN THE LOW LEVELS /SEE MORNING SOUNDING
FROM MPX/ HAS MADE IT DIFFICULT TO ACTUALLY GET MEASURABLE RAIN OUT
OF THESE SHOWERS...WITH MAJORITY OF STATIONS ONLY REPORTING A TRACE
OR 0.01. THEREFORE HAVE CAPPED POPS AT 50 OR LESS THE REST OF THE
DAY AND MAINTAINED A SCT SHOWER WORDING.

FOR TONIGHT INTO TUESDAY MORNING THE BIG QUESTION IS WHAT HAPPENS
WITH POTENTIAL CONVECTION COMING OUT OF NODAK. STORMS LOOK TO
INITIATE ON THE NOSE OF A LLJ AROUND 00Z THIS EVENING OVER NE MT AND
SPEND THE REST OF THE NIGHT WORKING ACROSS NODAK. BY THE
MORNING...WHAT IS LEFT OF THEM WILL BE WORKING INTO MN. BASED ON THE
13.12 NAM HANDLING OF THE LLJ...FAVORED THESE STORMS TO STAY NORTH
OF THE MPX CWA. HOWEVER...SEE THAT BY THE END OF THE 13.18
RAP...SAID LLJ IS A BIT FURTHER SOUTH...WHICH WOULD BRING THE
POTENTIAL FOR SOME SORT OF REMNANT SHOWERS WORKING TOWARD THE AXN
AREA. SPCWRF/NMM/ARW ALL SHOW SOME SORT OF REMNANT SHOWERS MOVING
ACROSS CENTRAL MN IN THE MORNING AS WELL...BUT GIVEN HOW DRY THINGS
ARE TURNING BEHIND THE SHOWERS OVER WI...FAVORED A DRY FORECAST FOR
TONIGHT. INSTEAD...WILL LIKELY START THE MORNING WITH EXTENSIVE
MID/UPPER LEVEL DEBRIS CLOUDS...THAT LOOK TO QUICKLY BLOW OUT OF
HERE BY THE AFTERNOON.

FOR FIRE WEATHER...WAS VERY CLOSE TO ISSUING A RED FLAG WARING OUT
WEST FOR TODAY...BUT SHIED AWAY AFTER WATCHING DEWPS CLIMB INTO THE
40S. HOWEVER...PLAYING HINDSIGHT FORECASTER...STARTING TO SEE MORE
AND MORE HUMIDITIES OUT WEST DROP TO NEAR OR BELOW 25 PERCENT...AND
GIVEN NEAR WIND ADVY STRENGTH WINDS OUT THERE NOW...A RED FLAG
WARNING MAY HAVE BEEN A GOOD IDEA AFTER ALL. WHAT THIS DOES DO
THOUGH IS INCREASE CONFIDENCE IN POTENTIAL FOR RED FLAG CONDITIONS
TUESDAY.

AS FOR TUESDAY...AS MENTIONED ABOVE...EXPECT EXTENSIVE CLOUD COVER
IN THE MORNING THAT CLEARS OUT BY THE AFTERNOON...PER COLUMN
CONDENSATE FORECAST FROM THE 13.12 SPCWRF. GIVEN WARMTH OF 925-850
MB TEMPS BY THE AFTERNOON...IT WILL NOT TAKE MUCH SUN TO SEE A BIG
BOOST IN TEMPS. LOOKING TO THE SW THIS AFTERNOON...SEEING WIDESPREAD
90-95 DEGREE TEMPS ACROSS NEB INTO SODAK. THIS AIRMASS WILL BE HERE
TOMORROW...SO CONTINUED TO RUN WITH FORECAST HIGHS VERY SIMILAR TO
WHAT PREVIOUS FORECAST HAD. WITH 925 MB TEMPS PUSHING 28C PLUS IN
SRN MN...WOULD NOT BE SURPRISED IF PLACES DOWN ALONG I-90 GET INTO
THE UPPER 90S...WITH THE RECORD OF 95 AT MSP CERTAINLY WITHIN
REASON.

BESIDE THESE WARM TEMPS...GRADIENT LOOKS TO TIGHTEN WITH THE
APPROACHING COLD FRONT...WITH WINDS EXPECTED TO INCREASE AGAIN
TOMORROW TO SPEEDS VERY SIMILAR TO WHAT WE SEE NOW. SAID COLD FRONT
WILL MOVE INTO WRN MN DURING THE AFTERNOON...WITH WINDS SWITCHING TO
THE WEST AND INCREASING IN STRENGTH BEHIND IT. WITH WINDS NOT BEING
A QUESTION FOR RED FLAG POTENTIAL TOMORROW...ATTENTION TURNS TO
HUMIDITIES. THIS REMAINS DIFFICULT THANKS TO VERY POOR HANDLING OF
SFC DEWPS BY GUIDANCE IN THE PAST COUPLE OF WEEKS. CONTINUED TO
UNDERCUT GUIDANCE DEWPS BY ABOUT 10 DEGS. WITH CURRENT DEWPS...MIN
HUMIDITIES CURRENTLY FORECAST TO FALL INTO THE 20 TO 25 PERCENT
RANGE FOR MOST OF MN. THE ONLY PLACE WHERE THE HUMIDITY IS
QUESTIONABLE IS CENTRAL MN...WHERE SLIGHTLY MORE CLOUD COVER MAY
KEEP TEMPERATURES LOWER AND HUMIDITIES A BIT HIGHER. GIVEN
SIGNIFICANT NATURE OF WEATHER EXPECTED WITH THE HIGH TEMPS...STRONG
WINDS...AND LOW HUMIDITIES...DECIDED TO UPGRADE FIRE WEATHER WATCH
TO A RED FLAG WARNING FOR ALL BUT CENTRAL MN...WHERE BIGGEST
QUESTION MARKS REGARDING TEMPS/HUMIDITIES EXISTS.

.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 315 PM CDT MON MAY 13 2013

GIVEN THE RECENT ISSUES MODELS HAVE DISPLAYED WITH OVERDOING
SURFACE/SOIL MOISTURE...ESPECIALLY WITH RESPECT TO
DEWPOINTS...ASSESSING THE CONVECTIVE POTENTIAL FOR TUESDAY EVENING
REMAINS CHALLENGING. THEREFORE...THE 65 TO 75 DEGREE DEWPOINTS THE
GFS/NAM/SREF/ECMWF DEPICT FOR 00Z WEDNESDAY ALONG THE MN/WI BORDER
ARE NOT TRUSTED...WHICH MEANS THE 3000 TO 4000+ J/KG PROGGED
MUCAPE VALUES ARE NOT RELIABLE EITHER. HOWEVER...GIVEN THE
ANTICIPATED DIURNAL HEATING AND DEGREE OF DEEP LAYER SHEAR THAT
DOES SEEM REALISTIC...AM NOT COMFORTABLE WITH A THUNDERSTORM-FREE
FORECAST FOR TUESDAY EVENING. HAVE INCLUDED 30-40 POPS FROM WEST
CENTRAL WI TOWARD SOUTHEAST MN FOR THE POSSIBILITY OF DEVELOPMENT
AS THE CAP ERODES EARLY TUESDAY EVENING.

ANY ACTIVITY QUICKLY LIFTS OUT OF THE FORECAST AREA BY 05Z
WEDNESDAY...WITH SPRING-LIKE CONDITIONS THEN ARRIVING FOR WEDNESDAY
AND THURSDAY AS NEARLY ZONAL FLOW DEVELOPS ACROSS THE CENTRAL CONUS.
HIGHS FOR BOTH DAYS WILL RANGE THROUGH THE 70S...WITH LOWS IN THE
UPPER 40S TO MID 50S.

FRIDAY INTO NEXT WEEKEND IS SHAPING UP TO SIGNAL A TRANSITION TO A
MUCH STORMIER PATTERN FOR THE UPPER MIDWEST. THE AFOREMENTIONED
ZONAL FLOW WILL BECOME A THING OF THE PAST AS A TROUGH DEEPENS OVER
THE SOUTHWESTERN CONUS...SHIFTS EASTWARD TOWARD THE PLAINS...AND
INDUCES SURFACE CYCLOGENENIS OVER THE PLAINS. PLENTY OF MOISTURE TO
WORK WITH THIS TIME...GIVEN THE ANTECEDENT FLOW FROM THE GULF. THE
SEVERE THREAT FOR SATURDAY CURRENTLY APPEARS TO NOSE INTO SOUTHERN
MN...ALTHOUGH...CHANGES IN THE SYNOPTIC PROGS COULD CERTAINLY SHIFT
THAT A BIT.

THE MID LEVEL TROUGH OF WESTERN ORIGIN EVENTUALLY CONGEALS WITH A
NORTHERN STREAM WAVE TO FORM ANOTHER CLOSED LOW SCENARIO OVER OUR
REGION FOR THE WEEK OF MAY 20TH...AS DEPICTED BY ENSEMBLE
MEANS...GFS...AND ECMWF. THIS COULD TRANSLATE TO HIGH TEMPERATURES
IN THE 50-60 DEGREE RANGE FOR A FEW DAYS WITH EXTENSIVE CLOUD COVER
AND SHOWERS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 110 CDT MON MAY 13 2013

STRONG WAA AROUND 850 MB HAS AREA OF -SHRA OVER ERN MN NOW PUSHING
INTO WRN WI. DESPITE A GOOD 10K FT LAYER OF DRY AIR ABOVE THE
SFC...RAIN HAS BEEN ABLE TO FIGHT ITS WAY TO THE GROUND THIS
MORNING...SO INCLUDED A COUPLE HOUR LONG MENTION OF -SHRA AT WI
TERMINALS...THOUGH WITH SAFELY VFR CONDS. WARM FRONT AT 18Z FROM
ABOUT MITCHELL...SD TO AROUND JAMESTOWN...ND. THIS LOOKS TO ENTER
WRN MN AROUND 21Z AND PUSH TO ABOUT THE MN/WI BORDER BY 12Z BEFORE
LOSING ITS DEFINITION. THIS WILL ALLOW WINDS AT MN TERMINALS TO
BECOME MORE WRLY TONIGHT...BEFORE GOING BACK TO THE SSE TUE MORNING
IN RESPONSE TO AN AREA OF LOW PRESSURE MOVING ACROSS THE CANADIAN
PRAIRIES. AS GRADIENT TIGHTENS...S WINDS WILL INCREASE AND BECOME
GUSTY AGAIN ACROSS MN TUE MORNING. COLD FRONT WILL BE MOVING INTO
WRN MN AROUND 18Z TUES AND WILL MOVE INTO THE TWIN CITIES BY
AROUND 00Z. FOLLOWING THE IDEA OF THE 12Z NAM THAT ANY
PRECIPITATION TONIGHT WILL STAY NORTH OF THE MPX AREA ON NOSE OF
LLJ.

KMSP...ANY RAIN SHOULD BE DONE BY 19Z. WITH ALL THE DRY AIR IN
PLACE...CONFIDENCE REMAINS HIGH THAT VIS AND CIG RESTRICTIONS
WILL REMAIN SAFELY VFR. CONFIDENCE IN WIND DIRECTION FORECAST
DOES DIMINISH FOR TONIGHT...AS PASSAGE OF WARM FRONT WILL COINCIDE
WITH A CONSIDERABLE SLACKENING OF THE GRADIENT. STILL ALL GUIDANCE
POINT TO WEST WINDS DEVELOPING OVERNIGHT THAT TRANSITION BACK TO
THE SSE BETWEEN 12Z AND 15Z. COLD FRONT WITH WIND SHIFT TO THE
WEST LOOKS TO ARRIVE BETWEEN 22Z AND 00Z. GIVEN STRENGTH OF CAP
IN PLACE AHEAD OF THE FRONT...CONFIDENCE IS HIGH THAT MSP WILL NOT
SEE ANY TSRA ACTIVITY WITH THIS FRONT...JUST A WIND SHIFT.

/OUTLOOK FOR KMSP/
WED...VFR. NW WINDS 10 KTS.
THU...VFR. WINDS W 5 KTS.
FRI...MVFR POSSIBLE WITH CHC -TSRA. WINDS SE 5-10 KTS.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...RED FLAG WARNING FROM NOON TO 8 PM CDT TUESDAY FOR MNZ047>051-
     054>070-073>077-082>085-091>093.

     FIRE WEATHER WATCH FROM TUESDAY AFTERNOON THROUGH TUESDAY
     EVENING FOR MNZ041>045-052-053.

WI...NONE.
&&

$$

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