Issued by NWS Bismarck, ND
000 FXUS63 KBIS 220819 AFDBIS AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BISMARCK ND 208 AM CST SUN NOV 22 2009 .SHORT TERM...TODAY THROUGH TUESDAY NIGHT... LATEST WATER VAPOR IMAGERY SHOWS A PROGRESSIVE FLOW IN ACTION WITH A SHORTWAVE TROUGH ALOFT ENTERING WESTERN NORTH DAKOTA. A 300MB 80KT JET STRETCHES FROM CENTRAL NORTH DAKOTA INTO MANITOBA. THE RIGHT ENTRANCE REGION IS PROMOTING UPWARD VERTICAL MOTION OVER CENTRAL NORTH DAKOTA PER IR SATELLITE IMAGERY WITH SCT TO BKN HIGH CLOUDS AS TOTAL MOISTURE COLUMN REMAINS RELATIVELY DRY. THIS JET EXITS THE AREA THIS MORNING WITH SINKING MOTION RETURNING/MOSTLY SUNNY SKIES BEHIND THE WAVE AND IN RESPONSE TO THE APPROACH OF A TRANSITORY RIDGE. THE NEXT UPPER LOW/TROUGH WAS SEEN MOVING INTO THE WESTERN WASHINGTON/OREGON COAST. MODELS IN FAIRLY GOOD AGREEMENT IN MOVING THE ENTIRE WAVE COMPLEX SOUTHEAST. CONCERNS IN THE SHORT TERM WILL REVOLVE AROUND PRECIPITATION CHANCES MAINLY OVER THE FAR SOUTHWEST AND FAR SOUTHEAST CWA TONIGHT THROUGH TUESDAY. THEREAFTER...THE NEXT CONCERN WILL BE AN ALBERTA CLIPPER PLOWING THROUGH TUESDAY NIGHT. OVERALL TEMPERATURES WILL TREND COLDER TODAY THEN REMAIN FAIRLY FLAT UNTIL TUESDAY NIGHT WHEN STRONG COLD AIR ADVECTION TAKES CONTROL. THE LATEST FOG/STRATUS IMAGERY LOOP SHOWS AN AREA OF LOW CLOUDS ACROSS NORTHWEST NORTH DAKOTA MOVING EAST WITH TIME. THE NAM 925-850MB MOISTURE VERIFIES FAIRLY WELL WHEN OVERLAID ON THE CURRENT IMAGERY. EXPECT THE BULK OF LOW CLOUDS TO REMAIN OVER NORTHERN NORTH DAKOTA NOW THROUGH 15Z FOLLOWING THE 925MB-850MB WINDS. ELSEWHERE...CURRENT HIGH LEVEL CLOUDS ARE MOSTLY OBSCURING STRATUS FROM BEING SEEN ON THE FOG/STRATUS IMAGERY...HOWEVER THERE ARE SOME HOLES AND SIGNS OF PATCHY LOW CLOUDS DEVELOPING IN OUR SOUTH CENTRAL ZONES. THIS IN LINE WITH THE CURRENT RELATIVE HUMIDITY TIME/HEIGHT CROSS SECTIONS. WILL PAINT SOME PATCHY CLOUDS INTO THE SKY GRIDS THIS MORNING BUT OVERALL EXPECT A QUICK RETURN TO MOSTLY SUNNY SKIES. AFTERNOON HIGH TEMPERATURES WILL BE ABOUT 10 DEGREES COOLER THAN SATURDAY`S HIGHS. FOR TONIGHT AND MONDAY...THE AFOREMENTIONED PACIFIC NORTHWEST LOW/TROUGH WILL DIVE SOUTHEAST AND GRAZE OUR SOUTHWEST ZONES. MAINTAINED A SLIGHT CHC SNOW TONIGHT INTO MONDAY MORNING AS THIS AREA IS CLOSEST TO THE UPPER LOW. A SURFACE LOW SPINS UP ACROSS NEBRASKA AND SOUTH DAKOTA MONDAY WITH AN INVERTED TROUGH JUST REACHING INTO SOUTHERN NORTH DAKOTA. THE GFS BRINGS PRECIPITATION UP THROUGH THIS AREA WHILE THE ECMWF IS FURTHER EAST AND SOUTH. A SLIGHT CHC TO CHC OF RAIN/SNOW IS POSSIBLE OVER OUR FAR SOUTHEAST ZONES GIVEN THE UNCERTAINTY BETWEEN THE MODELS. WILL LOWER POPS ELSEWHERE WITH MODELS IN GOOD AGREEMENT ON DRY CONDITIONS OTHER THAN THE SOUTHWEST AND SOUTHEAST. THE ENTIRE SYSTEM PUSHES FURTHER SOUTH TUESDAY MORNING WITH DRY WEATHER RESULTING THROUGH THE DAYLIGHT HOURS. FOR TUESDAY INTO TUESDAY NIGHT...AN ALBERTA CLIPPER SYSTEM APPROACHES OUR NORTHWESTERN ZONES TUESDAY AFTERNOON WHICH SWINGS A COLD FRONT THROUGH THE CWA TUESDAY EVENING...BETWEEN 00Z AND 06Z WEDS. BRISK NORTHWEST WINDS AND COLD AIR ADVECTION TAKE CONTROL AFTER MIDNIGHT. PRECIPITATION WILL BE LIMITED GIVEN MOISTURE SOURCE OF SYSTEM AND LACK OF ANY SIGNIFICANT MOISTURE ADVECTION INTO NORTH DAKOTA. SOME FLURRIES OR A SLIGHT CHANCE OF SNOW AT BEST TUESDAY NIGHT OVER FAR EAST CENTRAL NORTH DAKOTA WITH OUR WESTERN ZONES REMAINING DRY BUT BLUSTERY. .LONG TERM...WEDNESDAY THROUGH SUNDAY MEDIUM RANGE MODELS IN FAIR AGREEMENT AT BEGINNING OF EXTENDED WITH DIFFERENCES DEVELOPING BY LATE IN THE PERIOD. WILL GENERALLY USE ECMWF FOR THE GRIDS WITH THIS MODEL MORE CONSISTENT DURING THE PAST WEEK. DOUBLE LOWS OVER NORTHERN PLAINS TO GREAT LAKES AND MIDWEST AT BEGINNING OF PERIOD. SURFACE LOW INTO WISCONSIN AND ILLINOIS WITH FAIRLY GOOD CAA OVER THE NORTHERN PLAINS. COOLER DAY THAN PAST WEEK. MID LEVEL LOWS MERGE OVER MIDWEST ON THANKSGIVING WITH CAA CONTINUING THOUGH GENERALLY DRY OVER THE WESTERN PLAINS AS RIDGING DEVELOPS FROM NORTHERN ROCKIES TO CANADIAN PRAIRIE PROVINCES. SLIGHT CYCLONIC FLOW MAY PRODUCING A LITTLE LIGHT PRECIPITATION MID WEEK OVER FAR EASTERN PORTIONS OF FORECAST AREA. BY BEGINNING OF NEXT WEEKEND RIDGING FULLY OVER NORTHERN PLAINS AND WAA BEGINNING AHEAD OF NEXT ALBERTA CLIPPER WHICH DEVELOPS OVER SASKATCHEWAN AND ALBERTA SATURDAY AND SUNDAY. GFS BRINGS COLDEST AIR OF SEASON TO NORTHERN PLAINS ON SUNDAY AND SUNDAY NIGHT THOUGH GFS IS TRENDING WARMER AND CLOSER TO ECMWF AND WILL FOLLOW ECMWF. && .AVIATION... GUSTY WINDS AHEAD OF SECONDARY FRONT MOVING THROUGH WESTERN NORTH DAKOTA AND SMALL PATCH OF NEAR MVFR CLOUDS OVER NORTHERN TAF SITES ONLY CONCERNS WITH THIS AVIATION PACKAGE. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ KS/HW
