FXUS63 KMPX 290922 AFDMPX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 422 AM CDT TUE MAR 29 2011 .DISCUSSION... SUMMARY...NO MAJOR CHANGES TO THE 1-5 DAY FORECAST PERIOD. INCREASED POPS ON THURSDAY AND PROBABLY COULD HAVE GONE A LITTLE HIGHER TO INCLUDE LIKELY POPS. PRECIPITATION WILL BE LIGHT...BUT IT CERTAINLY LOOKS LIKE ENOUGH FOR A HUNDREDTH OF AN INCH IN MANY LOCATIONS. SLOW WARMING TREND THIS WEEK ON TRACK...LATEST 29.00Z GUIDANCE MIGHT BE A COUPLE DEGREES COOLER WITH THE TEMPERATURES IN THE WEDNESDAY THOUGH SATURDAY TIME FRAME. STILL HIGH UNCERTAINTY FOR A MORE SIGNIFICANT SYSTEM EXPECTED EARLY NEXT WEEK. TODAY THROUGH WEDNESDAY...DISCUSSIONS OF THE SHORT TERM FORECAST ARE PROBABLY SOUNDING A LITTLE LIKE A BROKEN RECORD...DUE TO THE PERSISTENT COOL AND DRY AIR MASS OVERHEAD AND NEARLY STATIONARY AREA OF HIGH PRESSURE. LIGHT SNOW ONCE AGAIN BLOSSOMED EARLY THIS MORNING ON THE FRINGE OF THE HIGH IN AREAS TO OUR SOUTHWEST...AIDED BY 800-600MB CONVERGENCE AND A LITTLE KICK FROM SHORT WAVE ENERGY IN SOUTH DAKOTA. THE FORECAST AREA WILL REMAIN TOO DRY TO SEE SNOW THIS MORNING...AT MOST FLURRIES IN FAR SOUTHWEST MN...BUT PORTIONS OF MN MIGHT ACTUALLY SEE A BIT MORE CLOUD COVER TODAY. THE PERSISTENCE OF THIS AIR MASS HAS BEEN IMPRESSIVE...THE DAILY 24-HR TEMPERATURE CHANGE HAS LOOKED REMARKABLY SIMILAR OVER THE PAST FEW DAYS WITH ONLY A SLIGHT WARMING TREND WITH TIME. THE KMPX SOUNDINGS TAKEN HERE IN CHANHASSEN SINCE FRIDAY EVENING HAVE REFLECTED NEARLY IDENTICAL PRECIPITABLE WATER VALUES: 0.10...0.11...0.12...0.12...0.12...0.12...0.10. THE PATTERN BEGINS TO BREAK DOWN ON WEDNESDAY AS 250MB JET JUST TO OUR SOUTH BUCKLES AND WEST COASTING RIDGING BECOMES MORE PRONOUNCED...SHOULD HELP TO ADVECT SLIGHTLY WARMER AIR INTO MN AND WI. TEMPERATURES LOOK CLOSE TO NORMAL WEDNESDAY. THURSDAY AND FRIDAY...WITH WARMTH AND RIDGING TO OUR WEST...SURFACE TROUGH BECOMES MORE DEFINED AND SLIDES ACROSS THE AREA ON THURSDAY AND FRIDAY. LOW LEVEL THICKNESSES AND FORECAST SOUNDINGS SUPPORT SNOW AT THE ONSET OF PRECIPITATION THURSDAY MORNING WITH THE FIRST PUSH OF ISENTROPIC LIFT IN WESTERN MN. EVEN WITH CLOUD COVER TEMPERATURES SHOULD RECOVER ENOUGH FOR UPPER 30S AND 40S BY THE TIME THE PRECIPITATION EXPANDS EASTWARD ACROSS MN AND WI. MOST OF THE LIQUID...LIKELY LESS THAN A TENTH OF INCH...APPEARS TO FALL AS RAIN. EVEN WHEN THICKNESS VALUES FALL ENOUGH TO SUPPORT CRYSTALS BELOW 850-925MB THURSDAY EVENING...CLOUD COVER SHOULD KEEP TEMPERATURES AT THE SURFACE FROM FALLING TOO QUICKLY AND THE BEST CHANCE OF A RETURN TO SNOW WOULD BE BETWEEN 06-12Z FRIDAY. SEE LITTLE TO NO SNOW ACCUMULATION WITH THIS EVENT. 29.00Z GUIDANCE DOES SHOW TWO DISTINCT SHORT WAVE IMPULSES...ONE THURSDAY AFTERNOON...AND THE OTHER FRIDAY MORNING. AS A RESULT...HARD TO CLEAR THE AREA OF PRECIPITATION BEFORE FRIDAY EVENING. EXTENDED...THE 28.12Z GUIDANCE SHOWED MUCH BETTER AGREEMENT AMONG THE GFS AND ECMWF IN TERMS OF TIMING FOR THE SYSTEM EARLY NEXT WEEK. THE 29.00Z RUNS ARE ACTUALLY STILL IN DECENT AGREEMENT IN LEE CYCLOGENESIS OCCURRING SATURDAY NIGHT AND SURFACE LOW EJECTING OUT IN THE PLAINS BY SUNDAY AFTERNOON. HOWEVER...THAT IS WHERE THE SIMILARITIES END...BECAUSE THERE ARE STILL LARGE DISCREPANCIES IN TRACK OF THE SURFACE LOW. NOT THAT THE DETAILS REALLY MEAN MUCH AT THIS POINT...BUT THE 29.00Z GFS DEVELOPS A POTENT LOW AND TRACKS IT ACROSS IA AND SOUTHERN WI SUNDAY NIGHT AND MONDAY. THE ECMWF IS MUCH FURTHER SOUTH AND GRADUALLY LOSES PACE WITH THE MORE AGGRESSIVE GFS. ALSO ADDING TO THE UNCERTAINTY IS THE LACK OF RUN- TO-RUN CONSISTENCY WHEN LOOKING AT DP/DT OVER THE PAST COUPLE DAYS. ALL WE CAN SAY FOR CERTAIN IS THAT THERE WILL BE A STRONG SPRING CYCLONE AFFECTING THE CENTRAL CONUS EARLY NEXT WEEK. && .AVIATION.../06Z TAF ISSUANCE/ SURFACE HIGH PRESSURE RIDGE EXTENDING FROM THE NORTHERN PLAINS INTO THE MIDWEST...WILL SLOWLY MOVE EAST. WEAK SURFACE TROUGH OVER THE WESTERN DAKOTAS...WILL SLIDE SOUTHEAST OVER INTO IOWA DURING THE PERIOD. LIGHT EASTERLY WIND FLOW WILL CONTINUE THE DRY AND EXCELLENT FLYING CONDITIONS OVER MOST AREAS THROUGH TUESDAY. THE EXCEPTION...WHERE CLOUDS AND CEILING HEIGHTS COULD LOWER UNDER 5000 FEET AGL...IS OVER THE SOUTHWEST MN NEAR KRWF TAF SITE. OTHERWISE...CLOUDS AND CEILINGS SHOULD GENERALLY BE AT OR ABOVE 10 THOUSAND FEET AGL. .MSP...NO SIGNIFICANT CLOUDS OR WEATHER DURING THE PERIOD. LIGHT EASTERLY WINDS. && .HYDROLOGY... MODIS SATELLITE PASSES OVER THE PAST COUPLE DAYS SHOW LITTLE SNOW COVER IN SOUTHERN MN...SOUTH OF THE MINNESOTA RIVER. THE EXCEPTION IS IN THE MINNESOTA RIVER VALLEY NORTHEAST OF A LINE FROM NEW ULM TO PIPESTONE...WHERE THE EFFECT OF LAST WEEKS SNOWFALL IS STILL QUITE EVIDENT. LATEST NOHRSC 48-HR CHANGE IN SNOW WATER EQUIVALENT SHOWS BETWEEN A TRACE AND 0.20 INCH LOSS SINCE SATURDAY ACROSS ALL OF MN AND WI...DESPITE WELL BELOW NORMAL TEMPERATURES - THE LATE MARCH SUNSHINE IS PLAYING A ROLE IN THIS SLOW MELT. STILL EXPECT AREAS NORTH OF THE MINNESOTA RIVER VALLEY TO SEE THE MELT ACCELERATE FOR THE SECOND OF THIS WEEK GIVEN THE WARMER TEMPERATURES. THE PRECIPITATION ON TUESDAY WILL HAVE NO AFFECT ON THE CURRENT FLOODING OR POTENTIAL SECOND CREST IN APRIL. A MORE SIGNIFICANT SYSTEM IS EXPECTED IN THE CENTRAL PART OF THE COUNTRY EARLY NEXT WEEK...BUT THERE IS STILL HIGH UNCERTAINTY IN LOCATION. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ CLF/MPG  FXUS63 KMPX 202207 AFDMPX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 407 PM CST SUN NOV 20 2011 .DISCUSSION... MUCH QUIETER WEATHER TODAY WITH 1031MB HIGH SITTING OVER MN. OVER THE NEXT WEEK...ONLY CHANCE FOR PRECIP LOOKS TO BE COMING IN THE FRIDAY NIGHT INTO SATURDAY NIGHT TIME FRAME AS A DEEP TROUGH WORKS ACROSS THE CENTER OF THE COUNTRY. OTHER THAN THAT...BIG CHALLENGE FOR THE FORECAST THIS WEEK WAS HOW FRESH SNOW PACK WILL IMPACT TEMPERATURES DURING THE BIG WARM UP THAT IS EXPECTED AS WE HEAD FOR THANKSGIVING. SYSTEM THAT BROUGHT US SNOW YESTERDAY ALREADY MOVING OFF INTO THE NORTH ATLANTIC THIS AFTERNOON. ZONAL FLOW IS QUICKLY TAKING CONTROL OF THE CONUS WITH A NICE BOWLING BALL LOW COMING INTO THE CENTRAL CALIFORNIA COAST. TONIGHT THROUGH FRIDAY. STRICTLY A TEMPERATURE FORECAST THIS PERIOD...WITH ONLY SYSTEM OF NOTE EXPECTED TO PASS OFF TO THE SE OF THE MPX CWA TUESDAY INTO WEDNESDAY /THIS IS THE CURRENT CALIFORNIA LOW/. 20.12 RUNS OF THE MODELS DID PULL THIS LOW NW QUITE A BIT TODAY...BUT ONLY CLOSE ENOUGH TO NOW BRING THE THREAT OF MOSTLY CLOUD SKIES TO SE MN INTO WI TUESDAY. BIG PLAYER FOR THE TEMPERATURES DURING THE WEEK WILL BE SNOW COVER IN PLACE FROM YESTERDAYS STORM. HIGH RES /1 KM/ MODIS SATELLITE PASS TODAY SHOWED THE SNOW PACK QUITE WELL...EXTENDING ACROSS CENTRAL SODAK AND MOST OF THE CWA. SNOW PACK DEEPEST FROM WEST CENTRAL MN THROUGH CENTRAL MN AND THIS IS WHERE THE HIGHEST IMPACT FROM THE SNOW ON TEMPERATURES IS EXPECTED OVER THE COMING DAYS. WENT LOWER WITH TEMPERATURES IN THIS DEEPER SNOW PACK REGION FOR BOTH HIGHS AND LOWS THROUGH THE HIGHS ON THURSDAY...BUT VERY WARM CONDITIONS WEDNESDAY NIGHT THROUGH THURSDAY NIGHT...WITH LOWS LIKELY STAYING ABOVE 30...SHOULD ALL BUT DO IN THIS SNOW PACK BY FRIDAY. MODEL OF CHOICE FOR TEMPERATURES WAS THE NAM TODAY...AS IT APPEARED TO INITIALIZE THE SNOW COVER THE BEST WHEN COMPARING FORECAST HIGHS AND LOWS OVER THE COMING DAYS. THE ONLY AREA WHERE THE NAM WAS NOT FOLLOWED AS CLOSELY IS SE OF THE DEEPER SNOW COVER...WHERE THE NAM WAS LOOKING A LITTLE TOO WARM ON TEMPERATURES. FRIDAY NIGHT THROUGH THE WEEKEND. DURING THE COURSE OF THE WEEK...WARM H5 RIDGE WILL BE BUILDING ACROSS THE CENTRAL CONUS...WITH A DEEP UPPER TROUGH PROGGED TO MOVE IN TO WRN NOAM. THIS HIGHLY AMPLIFIED TROUGH WILL BEGIN MOVING ON TO THE HIGH PLAINS ON FRIDAY...WITH A STRONG COLD FRONT EXPECTED TO HEAD OUT ACROSS THE PLAINS. DIFFERENCES BETWEEN THE GFS/ECMWF ARE RATHER LARGE TODAY IN TERMS OF HANDLING THIS SYSTEM OVER THE WEEKEND. THE GFS SENDS THE COLD FRONT ACROSS THE AREA FRIDAY AFTERNOON/NIGHT...WITH A SIGNIFICANT COOL DOWN TAKING PLACE ON SATURDAY. THE ECMWF IS MUCH SLOWER AND STRONGER...SENDING A SFC LOW INTO THE UPPER MS VALLEY ON SATURDAY...WITH MOST OF THE PRECIP COMING SATURDAY AND THE COOL DOWN HOLDING OFF UNTIL SUNDAY. GIVEN THE UNCERTAINTY AND LARGE SPREAD IN THE MODELS...STUCK WITH THE CENTRAL REGION MODEL BLEND FOR THE WEEKEND FORECAST. NO MATTER WHAT HAPPENS...LOOKS WARM ENOUGH THAT WHATEVER WERE TO FALL WILL COME DOWN MAINLY IN THE FORM OF RAIN. && .AVIATION.../18Z TAF ISSUANCE/ STUBBORN LOW CLOUDS /MVFR/ CONTINUE TO PREVAIL ACROSS PORTIONS OF EASTERN MN AND WESTERN WISCONSIN. AS THE SFC RIDGE SLOWLY BUILDS OVER THE UPPER MIDWEST...CLOUDS SHOULD BEGIN TO BREAKUP AND DISSIPATE OVER MN...AND NOT UNTIL THIS EVENING OR LATE IN THE AFTERNOON OVER WESTERN WISCONSIN. MID CLOUDS DEVELOPING OVERNIGHT OVER THE TAF SITES. LIGHT/VARIABLE WINDS TDA...AND SOUTHEAST WINDS 5 TO 10 KNOTS BY NOON MONDAY. KMSP...PESKY LOW CLOUDS ARE EXPECTED TO BREAKUP THIS AFTERNOON. REMAINING MOSTLY CLEAR THROUGH THIS EVENING. MID CLOUDS DEVELOPING DURING THE OVERNIGHT. LIGHT WINDS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ MPG/JVM