452 FXUS63 KMPX 291830 AFDMPX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 1230 PM CST WED JAN 29 2014 .UPDATE... 18Z AVIATION DISCUSSION ADDED BELOW. && .SHORT TERM...(TODAY THROUGH THURSDAY) ISSUED AT 406 AM CST WED JAN 29 2014 MAIN CONCERN IN THE SLIGHTLY EXTENDED SHORT TERM PERIOD IS SNOW MOVING IN LATE TONIGHT INTO THURSDAY MORNING...WHICH IS STARTING TO LOOK A LITTLE BIT MORE ROBUST. OUR PRIMARY SUSPECT IN THIS CASE CAN BE SEEN IN WATER VAPOR IMAGERY AND RAP H4-H3 PV ANALYSIS ROUNDING THE TOP OF THE WEST COAST RIDGE AND COMING ONSHORE ALONG THE WASH/BC BORDER THIS MORNING. 00Z MODELS HAVE COME IN IN PRETTY GOOD AGREEMENT ON THIS FEATURE...WITH THE MAIN DISAGREEMENT SURROUNDING AROUND JUST HOW MUCH PRECIP FALLS WITHIN THE HEAVIEST PART OF THE PRECIP SHIELD. AS FOR THE FORCING WITH THIS WAVE...MODELS SIMILAR WITH SHOWING THE WASH/BC PV FEATURE MOVING ACROSS SRN MN THURSDAY MORNING ON THE POLEWARD SIDE OF A 150 KT UPPER JET STREAK HEADING FOR IOWA...SO WE WILL BE ADDING LEFT EXIT DYNAMICS TO GO ALONG WITH THE PV FORCING. AT THE SFC...THE ARCTIC BOUNDARY THAT IS CURRENTLY MOVING SOUTH ACROSS ALBERTA WILL HAVE FOUND ITS WAY INTO NRN IOWA AND UP INTO THE CENTRAL U.P. OF MICH BY THURSDAY MORNING. AS THE UPPER FORCING CATCHES UP WITH THE SFC BOUNDARY...WE SEE A GOOD AREA OF LIFT BLOSSOM ALONG THE 295K THETA AS WARM AIR GETS PULLED UP AND OVER THE ARCTIC BOUNDARY. THE 295K SFC SHOWS LIGHT SNOW FALLING ACROSS JUST ABOUT THE ENTIRE CWA...BUT THE BEST FORCING IS CENTERED DOWN ALONG THE IA BORDER BETWEEN ABOUT 12Z AND 15Z. THIS IS ALSO COINCIDENT WITH WHERE THE PV FEATURE WILL BE MOVING ACROSS. TO NO SURPRISE... SRN MN...BETWEEN ABOUT ST. PETER AND THE IA BORDER IS WHERE ALL MODELS SHOW THE MOST QPF FALLING. ALL GUIDANCE SHOWS AT LEAST A QUARTER INCH OF QPF FALLING DOWN THERE...WHICH WOULD TRANSLATE TO ABOUT 3 INCHES OF SNOW...BUT SOME OF THE HI-RES MODELS AND INDIVIDUAL SREF MEMBERS SHOW OVER A HALF INCH OF QPF FALLING IN THIS AREA AS WELL...WHICH WOULD INDICATE THE POTENTIAL FOR SOME BORDERLINE WARNING SNOWS /6 INCHES/ DOWN IN SOUTH CENTRAL MN. IN FACT...THE PROBABILITIES FOR OVER 4 INCHES OF SNOW WITH THE 29.03 SREF IS UP OVER 60 PERCENT DOWN BETWEEN ST. PETER AND IA. WHAT WAS DONE WITH THIS FORECAST PACKAGE WAS TO BOOST POPS EVERYWHERE LATE TONIGHT THROUGH THURSDAY MORNING AND USED A BLEND OF THE DETERMINISTIC MODELS FOR QPF. THIS RESULTED AROUND 3 INCHES OF SNOW DOWN IN SRN MN...WITH AROUND 2 INCHES UP IN THE METRO THAT WILL FALL DURING THE MORNING RUSH ON THURSDAY. ALTHOUGH THIS WILL CERTAINLY SLOW THE MORNING COMMUTE...I THINK IT IS FAIR TO SAY THAT 2 INCHES OF SNOW DURING THE MORNING RUSH HERE WILL NOT CAUSE AS MANY PROBLEMS AS THE 2 INCHES OF SNOW FOR THE EVENING RUSH IN ATLANTA DID YESTERDAY. WE DID HAVE SOME HEALTHY DISCUSSION THIS MORNING WITH DMX AND ARX ABOUT ISSUING AN ADVY FOR THIS EVENT FOR A FEW REASONS. NUMBER ONE...TIMING WISE THIS WILL IMPACT MORNING DRIVES INTO WORK/SCHOOL. IN ADDITION...IF WE DO END UP SEEING SNOWFALL TOTALS UP CLOSER TO THE 5 INCH MARK...THEN THAT MEANS WE WOULD BE SEEING SNOWFALL RATES UP BETWEEN 1 AND 2 INCHES AN HOUR. FINALLY...ON THE BACK END OF THE SNOW THURSDAY AFTERNOON...GUSTY NW WILL RETURN IN THE WAKE OF THE COLD FRONT...MEANING THERE WILL BE SOME BLOWING AND DRIFTING CONCERNS AS WELL. STILL LOTS OF UNCERTAINTIES THOUGH AS TO JUST HOW MUCH QPF AND THEREFORE SNOW THIS WILL PRODUCE...AS A RESULT WE DECIDED THAT THERE WAS ENOUGH TIME WITH THIS UNCERTAINTY ON SNOWFALL AMOUNTS TO LET THE NEXT SHIFT GET ONE MORE LOOK AT MODEL RUNS BEFORE DECIDING ON ANY HEADLINES. .LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY) ISSUED AT 406 AM CST WED JAN 29 2014 PAST THURSDAY/S SYSTEM...THE MEAN UPPER LEVEL PATTERN CHGS SOME. THE MAIN CHG IS THE UPPER TROUGH MOVES FURTHER TO THE WEST WITH A MORE POSITIVE TILT TROUGH FOR MOST OF NORTH AMERICA FROM THE ROCKIES TO THE EAST COAST THROUGH THE FIRST WEEK OF FEBRUARY. THIS WOULD KEEP THE COLD PATTERN CONTINUING ACROSS THE UPPER MIDWEST. THERE IS ANOTHER CHG RELATED TO THE UPPER JET WHICH HAS A MORE PRONOUNCED SOUTHERN JET COMPARED TO A SPLIT FLOW REGIME. THIS WOULD KEEP OUR REGION QUIET. ALTHOUGH TWO WEAK FRONTAL BOUNDARIES DO MOVE ACROSS THE UPPER MIDWEST THIS WEEKEND...AND AGAIN NEXT WEEK...THIS IS MAINLY REINFORCING SHOTS OF COLD AIR. AS PER THE STRONGER SOUTHERN JET TAKING PLACE THIS WEEKEND...AND INTO NEXT WEEK...MOST OF THE ACTIVE WX WILL REMAIN SOUTH OF THE UPPER MIDWEST. LOOKING AT NORMALIZED ANOMALY EXTREMES OFF THE GEFS FOR 92/85/70H TEMPS...NO BIG COLD OUTBREAKS EXPECTED WITH ONLY THE TEMPORARY TEENS TO SINGLE DIGITS BLW ZERO FOR OVERNIGHT LOWS...AND HIGHS IN THE SINGLE DIGITS TO THE TEENS ABV ZERO. THIS IS STILL WELL BLW NORMAL...BUT NOT AS EXTREME AS IN THE PREVIOUS WEEKS. IF YOU COMPARE THESE EXTREME ANOMALIES FOR THE FIRST WEEK OF JANUARY WHERE TEMPS FELL TO -23 AT MSP...THESE EXTREME VALUES WERE 3 TO 4 STANDARD DEVIATIONS BLW NORMAL. NEXT WEEK THESE EXTREME VALUES ARE 1 TO 2 STANDARD DEVIATIONS BLW NORMAL. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON) ISSUED AT 1218 PM CST WED JAN 29 2014 VFR CIGS WILL DOMINATE THIS AFTERNOON AND INTO TONIGHT AS INCREASING MID/HIGH CLOUDS BUILD IN...AND SOUTHWEST WINDS STILL REMAIN ON TRACK TO BEGIN GUSTING THIS AFTERNOON. TEMPERATURES HAVE QUICKLY CLIMBED AS EXPECTED...AND WILL TOP OUT IN THE 20S TO LOWER 30S ACROSS THE FA THIS AFTERNOON. FOR THE OVERNIGHT INTO THURSDAY...A QUICK BURST OF ACCUMULATING SNOW WILL MOVE ACROSS THE AREA...MOST HEAVILY IMPACTING THE TC METRO AND AREAS SOUTH TO THE IOWA BORDER. TERMINALS IN THIS REGION CAN GENERALLY EXPECT 2-4 INCHES OF SNOW...PRIMARILY COMING BETWEEN 12Z AND 18Z TOMORROW. CIGS WILL LIKELY TO DROP TO LIFR FOR A PORTION OF THIS TIME PERIOD. STC AND AXN REMAIN A LITTLE TOO FAR NORTH TO BE AS HEAVILY IMPACTED...AND WILL SEE LIGHTER ACCUMULATIONS AND BETTER OVERALL CIGS. WINDS DECREASE THIS EVENING IN THE VICINITY OF THE INCOMING FRONT. THE SNOW WILL END BY ABOUT MIDDAY THURSDAY AND VFR CIGS WILL QUICKLY RETURN UNDER CAA AND CLEARING SKIES WITH BLUSTERY NW WINDS. KMSP...1230Z TO 1500Z LOOKS TO BE LIFR WITH MOST OF THE SNOW ACCUMULATION OCCURRING DURING THIS PERIOD. BETTER MODEL AGREEMENT TODAY HAS INCREASED OUR CONFIDENCE IN THE INTENSITY AND TIMING OF THIS INCOMING SNOW. DO EXPECT THE CEILINGS TO DROP DOWN TO BELOW 1K FT DURING THIS PERIOD. TOMORROW AFTN WILL SEE MAJOR IMPROVEMENT WITH STRONG NW WINDS. /OUTLOOK FOR KMSP/ THU NIGHT...VFR. WINDS NW AT 10-15KTS. TURNING COLD. FRI...VFR. WINDS WSW 5 KTS. SAT...VFR. WINDS SW 5KTS EARLY BCMG NW AT 10G15KTS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ SHORT TERM...MPG LONG TERM...JLT AVIATION...SPD