RSS FeedsIssued by NWS Aberdeen, SD
000 FXUS63 KABR 222125 AFDABR AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ABERDEEN SD 325 PM CST SUN NOV 22 2009 .SHORT TERM...TONIGHT THROUGH TUESDAY NIGHT MAIN CHALLENGE IN THE NEAR TERM IS PRECIPITATION CHANCES BEGINNING LATER TONIGHT. THE MODELS ARE IN FAIRLY GOOD AGREEMENT...AND GENERALLY FOLLOWED A BLEND OF THE NAM AND GFS. AN UPPER LEVEL TROUGH CURRENTLY OVER THE PLAINS WILL SLIDE EASTWARD TONIGHT...WITH A SECOND TROUGH SLIDING OVER THE ROCKIES. WILL BEGIN TO SEE SOME ENERGY FROM THE WESTERN TROUGH REACH THE WESTERN PART OF THE STATE LATE TONIGHT. THE TROUGH SLIDES OVER THE PLAINS ON MONDAY...WITH THE MAIN LOW CENTER OVER WESTERN NEBRASKA AND WESTERN KANSAS. THE TROUGH SLOWLY PUSHES EASTWARD MONDAY NIGHT...BECOMING CENTERED OVER THE EASTERN PLAINS. THE MAIN LOW CENTER SWINGS NORTHEASTWARD TO JUST EAST OF THE CWA ON TUESDAY...WITH WEAK RIDGING PUSHING OVER THE WESTERN AND CENTRAL PART OF THE STATE AHEAD OF ANOTHER TROUGH SETTING UP OVER SASK. THIS TROUGH DROPS OVER THE NORTHERN PLAINS TUESDAY NIGHT. AT THE SURFACE...WEAK HIGH PRESSURE WILL BE OVER THE PLAINS THIS EVENING....THEN LOW PRESSURE APPROACHES FROM THE WEST. AS SOME LINGERING UPPER LEVEL ENERGY SLIDES ACROSS THE EASTERN CWA...MAY SEE SOME RAIN SHOWERS DEVELOP LATE TONIGHT ALONG AND EAST OF THE SISSETON HILLS. THE SURFACE LOW STRENGTHENS OVER THE SOUTHERN PLAINS ON MONDAY...WITH AN INVERTED TROUGH DEVELOPING NORTHWARD OVER THE EASTERN PLAINS. THIS TROUGH WILL BE THE FOCUS FOR CONTINUING PRECIPITATION CHANCES THROUGH THE DAY TUESDAY. WILL KEEP CHC POPS GOING ACROSS THE EASTERN CWA THROUGH THE DAY TUESDAY. MAY SEE A FEW SHOWERS ACROSS THE CENTRAL AND WEST DURING THE DAY MONDAY...THEN DIMINISHING PRECIPITATION CHANCES IN THOSE AREAS AS HIGH PRESSURE BEGINS TO NOSE OVER THE WESTERN PART OF THE STATE MONDAY NIGHT THROUGH TUESDAY. KEPT ALL THE PRECIPITATION MENTION AS RAIN AS CLOUD COVER SHOULD HELP KEEP TEMPERATURES UP. MODEL TIME SECTIONS INDICATE ABOVE FREEZING TEMPERATURES FROM THE SURFACE TO 800 MB THROUGH MOST OF THE PERIOD. H85 TEMPS REMAIN IN THE SINGLE DIGITS ABOVE ZERO THROUGH TUESDAY EVENING BEFORE FALLING BELOW ZERO. THIS SHOULD ALLOW FOR TEMPERATURES A GOOD 5 TO 10 DEGREES ABOVE NORMAL. .LONG TERM...WEDNESDAY THROUGH SUNDAY AT THE START OF THE EXTENDED FORECAST...STILL EXPERIENCING THE EFFECTS OF UPPER LEVEL LOW PRESSURE DIVING INTO THE BACK-SIDE OF A LONGWAVE TROF OF LOW PRESSURE OVER THE EASTERN HALF OF THE UNITED STATES. STEEP ENOUGH LOW LEVEL LAPSE RATES IN SUB-FREEZING AIR...SHOULD BE ENOUGH TO SUPPORT SOME ISOLATED/WIDELY SCATTERED SNOW SHOWERS WITH THIS UPPER LOW ON WEDNESDAY AS IT DIVES SOUTHWARD THROUGH THE DAKOTAS ON ITS WAY TOWARD THE MID-MISSISSIPPI RIVER VALLEY. BOUNDARY LAYER AIR WILL REMAIN COOL /CLOSE TO NORMAL/ RIGHT ON INTO THURSDAY WITH COOL CANADIAN HIGH PRESSURE IN PLACE. BY FRIDAY...HOWEVER...HIGH PRESSURE ALOFT WORKS INTO THE REGION...AND RETURN FLOW SETS UP IN THE LOW LEVELS...SIGNALING THE START OF A MODEST WARM UP HEADING INTO THE WEEKEND. THERE IS ANOTHER AREA OF LOW PRESSURE ALOFT FORECAST TO WORK ACROSS THE INTERNATIONAL CANADIAN/US BORDER DURING THE WEEKEND /DAY 6 AND 7 TIMEFRAME/. THIS SYSTEM IS CURRENTLY PROGGED TO WORK THROUGH IN NORTHERN BRANCH OF JET ENERGY IN A SPLIT FLOW PATTERN. AND...CURRENTLY THE ONLY WX IMPACTS FROM THIS LOW AS IT PASSES BY TO THE NORTH OF THIS CWA IS A DRY COLD FRONTAL PASSAGE. THE DEGREE OF COLD AIR ADVECTION FOLLOWING THE FROPA REMAINS THE BIG QUESTION MARK. SOME OF THE MOST RECENT GFS MODEL SOLUTIONS ARE SUPPORTING A NOTABLE COOL DOWN BY THE START OF NEXT WEEK...WHILE THE ECMWF MODEL HAS BEEN MAINTAINING A SOMEWHAT WARMER SCENARIO HEADING INTO NEXT WEEK. && .AVIATION... FLYING WEATHER CONDITIONS ARE VFR AT THIS TIME...AND SHOULD STAY THAT WAY FOR THE REMAINDER OF TODAY. HOWEVER...IFR LOW CLOUDS AND FOG ARE NOT FAR AWAY...LESS THAN 100 MILES TO THE SOUTH AND EAST OF THE KATY TERMINAL. GIVEN THE EXPECTED PRESSURE PATTERN FORECAST TO SET UP TONIGHT...LOW LEVEL WINDS SHOULD BECOME EAST-SOUTHEAST AND DRAW SOME OF THE HIGHER MOISTURE AIR /INCLUDING THESE LOW CLOUDS AND FOG/ NORTHWESTWARD INTO THIS FORECAST AREA...IN PARTICULAR INTO THE KATY TERMINAL AGAIN. SOME FORM OF IFR FLYING WEATHER IS EXPECTED TO RETURN TO THE KATY TERMINAL TONIGHT...LASTING INTO THE DAYTIME HOURS ON MONDAY. ELSEWHERE...VFR FLYING WEATHER IS EXPECTED TO PERSIST TONIGHT AND MONDAY AT THE KMBG...KPIR AND KABR TERMINALS...ALTHOUGH...THE KPIR AND KABR TERMINALS APPEAR TO BE ON THE FRINGE OF WHERE THIS LOW LEVEL MOIST AIR IS ABLE TO MOVE TO OVERNIGHT. THERE MAY BE SOME MVFR OR IFR GROUND FOG DEVELOPING TOWARD MORNING AT THESE TWO TERMINALS...WHICH WOULD REQUIRE A FEW HOURS TO BURN OFF MONDAY MORNING. OTHERWISE...LOOK FOR EASTERLY WINDS TONIGHT TO BECOME NORTHERLY WINDS ON MONDAY AT ALL TERMINALS...AS A LOW PRESSURE SYSTEM WORKS SOUTHEASTWARD OUT OF THE ROCKIES ONTO THE PLAINS. THERE IS A SMALL CHANCE OF SOME LIGHT RAINFALL ASSOCIATED WITH THIS LOW PRESSURE SYSTEM ON MONDAY AT KATY. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ SHORT TERM...PARKIN LONG TERM...DORN AVIATION...DORN WEATHER.GOV/ABERDEEN
