291 FXUS63 KFGF 290202 AFDFGF AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND FORKS ND 802 PM CST MON JAN 28 2013 .DISCUSSION... CURRENT HEAVY SNOW BAND HAS DEVELOPED AS PROGGED...AND WINTER STORM WARNING HEADLINES LINE UP WELL WITH CURRENT BAND. REPORTS SO FAR INDICATE ABOUT 2-4 INCHES HAS FALLEN FROM AROUND FARGO SOUTHWEST TO LIDGERWOOD...WITH LOCALLY HIGHER AMOUNTS LIKELY NEAR GWINNER/LIDGERWOOD WHERE 1/4SM VSBYS HAVE BEEN COMMON OVER THE PAST FEW HOURS. THE SNOW BAND WILL CONTINUE TO BE FED BY PWATS OVER 0.50 INCHES AND STRONG 850-700MB FGEN AIDING OMEGA FIELDS...AND EXPECT IT TO SLOWLY MOVE SOUTH AND EAST OVERNIGHT. THERE IS ALSO UPPER LEVEL DIVERGENCE AND A SHORTWAVE MOVING THROUGH SW FLOW ALOFT. THERE IS NO SFC WINDS TO SPEAK OF...SO THIS IS A CLASSIC NARROW/DEFORMATION/FGEN SNOW BAND WHERE 6-8 INCHES WILL BE COMMON IN THE CENTER...WITH LOCALIZED HIGHER AMOUNTS NEAR PERSISTENT HEAVIER BANDS. THE SNOW DISSIPATES QUICKLY TO THE NORTH AND NO SNOW HAS FALLEN IN WESTERN POLK...TRAILL OR STEELE COUNTIES...SO WILL BE CAN CELLING THE WINTER WEATHER ADVISORIES HERE. WE COULD BE CLOSE TO WARNING CRITERIA SNOW IN NORTHERN BELTRAMI...BUT THINKING IT SHOULD BE AROUND 5 INCHES HERE SO WILL HOLD ON A WARNING HERE...BUT MONITOR OVERNIGHT. WE WILL TRIM SNOW AMOUNTS ON THE NORTHERN FRINGE OF THE HEAVIER SNOW BAND...BUT OVERALL NOT MUCH CHANGE IS NEEDED WITH THIS HEAVY SNOW BAND. && .AVIATION... THE MAIN RESTRICTION TO VSBY WILL BE IN HEAVY SNOW BAND IN THE SOUTH OVERNIGHT. THERE IS STILL SOME PATCHY FOG THOUGH IN THE NORTH...WITH IFR/MVFR CONDITIONS NEAR ANY FOG. THERE WILL BE ANOTHER BAND OF MVFR CIGS DROPPING SOUTH TOMORROW WITH COLDER AIR FILTERING INTO THE AREA AND INCREASING NORTHERLY WINDS BEHIND COLD FRONT. && .PREV DISCUSSION... /ISSUED 348 PM CST MON JAN 28 2013/ DISCUSSION...FORECAST CHALLENGE WILL BE POTENTIAL HEAVY SNOW AND TEMPERATURES. MODELS IN GOOD AGREEMENT WITH TRACK OF EXPECTED HEAVY SNOW. BAND OF SNOW WHICH WILL BECOME HEAVY AT TIMES IS SETTING UP ABOUT AS EXPECTED FROM CENTRAL SD THROUGH SE ND. THIS ASSOCIATED WITH NE LIFTING SHORTWAVE COMBINED WITH IMPRESSIVE BAND OF FRONTOGENETIC FORCING. THIS SCENARIO WILL LEAD TO A RELATIVELY NARROW BUT INTENSE BAND OF SNOW. MODELS HAVE SHIFTED SNOW BAND SLIGHTLY NORTHWARD HAVING MAIN SNOW AXIS FROM FAR SW CORNER OF FA NE THROUGH VCNTY FAR TO BJI/PKD. WITH PRECIPITABLE H2O VALUES OVER A HALF INCH PLENTY OF AVAILABLE MOISTURE. HAVE ISSUED WINTER STORM WARNINGS ACCORDINGLY. ISSUED A WINTER WEATHER ADVISORY ON EACH SIDE OF WARNING HOWEVER WILL LIKELY SEE A SHARP CUT OFF FROM SIGNIFICANT SNOW FALL TO NEAR NOTHING. INITIAL FREEZING RAIN POTENTIAL ACROSS SE FA MAY ALSO MAKE FOR CHALLENGING SNOW FORECAST. EXPECT BAND OF SNOW TO LIFT NE DURING THE EVENING AND NOT LIKELY TO TAPER OFF UNTIL LATE TONIGHT. TEMPERATURES SHOULD REMAIN MILD TONIGHT WITH COOLEST TEMPERATURES OVER FAR NW WHERE COLD ADVECTION KICKS IN LATE TONIGHT. SNOW SHOULD WIND DOWN TUESDAY AM. STEADY COLD ADVECTION DURING THE DAY WILL LIKELY LEAD TO MAX TEMPERATURES DURING THE MORNING. COLD ADVECTION CONTINUES THROUGH MIDWEEK AS ARCTIC AIR DROPS SOUTH. WITH SURFACE HIGH DROPPING INTO WESTERN DAKOTAS FA WILL STAY WITHIN ZONE OF SURFACE PRESSURE GRADIENT. THIS ALONG WITH POTENTIAL FOR CLOUDS MAY LIMIT TEMPERATURE DROP HOWEVER WIND CHILLS WILL BECOME AN ISSUE. LONG TERM (THU NIGHT-MON)... THE FA WILL REMAIN IN NORTHWEST FLOW ALOFT DURING THE ENTIRE LONG TERM PERIOD. THIS WILL RESULT IN A SOUTHWEST TO NORTHEAST THERMAL GRADIENT OVER THE AREA AS WELL WITH EACH MODEL SLIGHTLY DIFFERENT. DESPITE THESE SLIGHT DIFFERENCES THEY SEEM TO AGREE ON THE TREND BY SAT OF NEAR NORMAL TEMPS. THE COLDEST DAY SHOULD BE FRI BEFORE TEMPS START CLIMBING BACK TOWARD NORMAL. THERE STILL APPEAR TO BE SOME WEAK IMPULSES DROPPING DOWN THRU THE AREA WHICH MAY BRING CHANCES FOR LIGHT SNOW FRI/FRI NIGHT AND AGAIN SUN/SUN NIGHT. NEITHER OF THESE WEAK IMPULSES SHOULD BRING MUCH FOR ACCUMULATIONS. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...WINTER STORM WARNING UNTIL 6 AM CST TUESDAY FOR NDZ039-049-052- 053. WINTER WEATHER ADVISORY UNTIL 6 AM CST TUESDAY FOR NDZ038. MN...WINTER STORM WARNING UNTIL 6 AM CST TUESDAY FOR MNZ002-003- 015>017-022>024-027>030. WINTER WEATHER ADVISORY UNTIL 6 AM CST TUESDAY FOR MNZ006-009- 013-014-031-032-040. && $$ DK