377 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