610 FXUS63 KFGF 290855 AFDFGF AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND FORKS ND 355 AM CDT MON APR 29 2013 .SHORT TERM...(TODAY THROUGH TUESDAY) ISSUED AT 355 AM CDT MON APR 29 2013 PRIMARY CONCERN WILL BE RAIN CHANCES AND AMOUNTS TONIGHT INTO EARLY TUESDAY MORNING. GFS/NAM/ECMWF/GEM SURFACE LOW TRACKS AND ASSOCIATED QPF ARE NOW RELATIVELY SIMILAR...SO WILL USE A BLENDED SOLUTION FOR THIS FORECAST. FOR TODAY...CLEAR SKIES THIS MORNING WILL GIVE WAY TO INCREASING CLOUD COVER FROM WEST TO EAST AHEAD OF THE NEXT PACIFIC WAVE CURRENTLY CRASHING ONTO THE BRITISH COLUMBIA COAST. LIGHT WIND WILL INCREASE FROM THE SOUTH AS THE PRESSURE GRADIENT STRENGTHENS WITH SOME AFTERNOON GUSTS UP TO 25 MPH. INCREASING WARM AIR ADVECTION AND MODEST BOUNDARY LAYER MIXING SHOULD ALLOW TEMPERATURES TO CLIMB INTO THE MID TO UPPER 60S ACROSS THE SOUTHERN VALLEY AND INTO THE FORESTS OF NORTHWEST MN. FARTHER NORTH AND WEST...EXPECT SLIGHTLY COOLER TEMPERATURES FROM THE MID 50S TO LOWER 60S. AREAS WITH SNOW COVER ACROSS THE DEVILS LAKE BASIN NOT LIKELY TO BREAK OUT OF THE 40S. DECREASED POPS THIS AFTERNOON ACROSS THE WESTERN FORECAST AREA INTO THE CHANCE CATEGORY AS IT APPEARS DRY LOW-MID LEVELS WILL TAKE SOME TIME TO SATURATE. MOST OF TODAY SHOULD BE DRY WITH MAIN PRECIPITATION EVENT BEGINNING THIS EVENING AND CONTINUING THROUGH THE NIGHT. VERY STRONG 700 HPA FRONTOGENESIS...MODEST DIVERGENCE ALOFT AHEAD OF A 100+ KT 300 HPA JET...AND PRECIPITABLE WATER FROM 0.75 TO 1.0 INCHES WILL RESULT IN RAPID DEVELOPMENT OF RAIN SHOWERS ACROSS MUCH OF THE FORECAST AREA. STILL NOT MUCH INSTABILITY...BUT WILL MAINTAIN ISOLATED THUNDER MENTION DUE TO THE STRENGTH OF THE FORCING. THE HEAVIEST BAND OF RAIN SHOULD STRETCH FROM NEAR COOPERSTOWN TO GRAND FORKS TO WARROAD AND BAUDETTE WHERE 0.75 TO 1.0 INCH ACCUMULATION IS POSSIBLE. ELSEWHERE...EXPECT 0.25 TO 0.75 INCHES...EXCEPT THE SOUTHERN VALLEY INTO ADJACENT PORTIONS OF WEST CENTRAL MN WHERE LESS THAN 0.25 INCHES WILL FALL. WITH THE WARM TEMPERATURES TODAY AND RAINFALL THIS EVENING AND OVERNIGHT...WILL CONTINUE THE AREAL FLOOD WATCH. SEE HYDROLOGY SECTION BELOW FOR OTHER IMPACTS TO RIVERS AND OVERLAND FLOODING. RAIN SHOWERS WILL MOVE QUICKLY TO THE EAST TUESDAY MORNING WITH ONLY SOME LINGERING ACTIVITY ALONG THE CANADIAN BORDER THROUGH THE DAY. TEMPERATURES TUESDAY WILL BE COOLER WITH AFTERNOON HIGHS FROM THE MID 40S TO THE MID 50S. WINDS WILL SHIFT TO THE WEST AND BECOME QUITE BREEZY BY THE AFTERNOON. .LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY) ISSUED AT 355 AM CDT MON APR 29 2013 TUESDAY NIGHT INTO WEDNESDAY WILL BE DRY...BUT COLD FOR THE START OF MAY. 850 HPA TEMPERATURES BEHIND THE FRONT FALL FROM -6 TO -10 C...RESULTING IN DAYTIME HIGHS WEDNESDAY FROM THE MID 30S TO THE MID 40S...A SOLID 20 DEGREES BELOW NORMAL. LOWS WEDNESDAY MORNING WILL BE IN THE 20S TO LOWER 30S. THURSDAY THROUGH SUNDAY...FOR THE END OF THE WORK WEEK AND INTO THE WEEKEND...MEDIUM RANGE MODELS CONTINUE TO STRUGGLE ON HOW THEY HANDLE A CUT OFF LOW MEANDERING OVER THE CENTRAL CONUS. THEY ALL HAVE A HIGHLY AMPLIFIED UPPER TROUGH DIGGING INTO THE PLAINS ON THURSDAY AND STARTING TO CUT OFF OVER EASTERN NEB/SD...BUT DIFFER QUITE A BIT ON WHERE THEY TAKE THE CUT OFF LOW. THE GFS KEEPS THE LOW OVER THE MID MS VALLEY THROUGH SUNDAY...WHILE THE ECMWF STARTS OFF IN THAT AREA BUT THEN KICKS THE SYSTEM FARTHER NORTH AND WEST WHERE IT MOVES OVER OUR CWA THEN OFF INTO CANADA. THE GEM IS AN OUTLIER AND HAS A MUCH WEAKER CUT OFF OVER THE LOWER MS VALLEY. UNCERTAINTY IS HIGH AS NONE OF THE MODELS WILL HANDLE THESE TYPE OF SYSTEMS VERY WELL. HOWEVER...EVEN THE FARTHER SOUTH AND EAST GFS BRINGS SOME PRECIP RETROGRADING BACK INTO OUR CWA DURING THE FRIDAY/SATURDAY TIME FRAME. WILL CONTINUE TO KEEP 20-50 POPS THAT ALLBLEND GIVES US MAINLY FOR OUR SOUTHEASTERN COUNTIES. TEMPS WILL REMAIN BELOW SEASONAL AVERAGES WITH COLD HIGH PRESSURE STARTING OUT THE PERIOD AND THEN GIVING WAY TO CLOUDS AND PRECIP. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT) ISSUED AT 1146 PM CDT SUN APR 28 2013 THE AVIATION DISCUSSION WILL BE TEMPORARILY SUSPENDED BEGINNING AT 12 UTC 29 APRIL DUE TO ONGOING FLOODING ACROSS THE RED RIVER BASIN. THE DISCUSSION WILL RESUME ONCE WATER LEVELS RECEDE AND ASSOCIATED WARNINGS ARE CANCELLED OR ALLOWED TO EXPIRE. LIGHT WINDS MONDAY MORNING WILL INCREASE FROM THE SOUTH BY EARLY AFTERNOON...WITH GUSTS UP TO 25 KNOTS POSSIBLE THROUGH THE AFTERNOON HOURS. CLEAR SKIES EXPECTED OVERNIGHT AND INTO MONDAY AFTERNOON. CLOUDS WILL INCREASE AND LOWER AHEAD OF THE NEXT WEATHER SYSTEM...WITH RAIN BECOMING LIKELY AT MOST SITES MONDAY EVENING AND INTO THE OVERNIGHT HOURS. THE MAIN CHALLENGE WILL BE CIGS AND NOT SURE HOW LOW THEY WILL BE. KEPT CIG HEIGHTS VFR...BUT LOWER HEIGHTS ARE POSSIBLE. && .HYDROLOGY... ISSUED AT 930 PM CDT SUN APR 28 2013 FLOODING CONTINUES ON THE RED RIVER AND MOST OF ITS TRIBUTARIES. THE POINT RIVER FORECASTS ALREADY ACCOUNT FOR THE POTENTIAL RAINFALL ON MONDAY NIGHT AND EARLY TUESDAY MORNING...WHICH IS EXPECTED TO TOTAL FROM A QUARTER TO A HALF INCH IN MANY SPOTS...WITH LOCAL AMOUNTS UP TO AN INCH. IF MORE THAN AN INCH OF RAIN FALLS ON A LOCALIZED BASIS IN SOME BASINS THOUGH...THERE MAY STILL BE SOME IMPACT ON ULTIMATE CRESTS FOR SOME LOCATIONS. ON THE RED RIVER...THE FORECAST CREST AT FARGO WAS LOWERED TO AROUND 37 FEET EARLIER ON SUNDAY BASED ON MORE INFILTRATION AND LOWER FLOWS COMING IN ON THE WILD RICE RIVER. THE CREST AT FARGO IS EXPECTED TO OCCUR TUESDAY OR WEDNESDAY. THE CREST WILL REACH EAST GRAND FORKS BY NEXT WEEKEND...BUT WILL NOT REACH THE CANADIAN BORDER UNTIL MID MAY. ON THE PEMBINA RIVER...FORECAST RIVER LEVELS HAVE BEEN INCREASED IN RESPONSE TO RAPID INCREASES IN LOCAL RUNOFF AND EXPECTED FLOW OUT OF SOUTHERN CANADA...WHICH IS FORECAST AROUND 7500 CFS AT WINDYGATES THIS WEEK. LEVELS ARE NOW EXPECTED TO REACH STAGES WHERE BREAKOUT FLOW AND FLOODING OF OVERLAND AREAS OCCURS DOWNSTREAM OF WALHALLA TOWARD NECHE. ELSEWHERE...WE EXPANDED AREAL FLOOD WARNINGS INTO SEVERAL ADDITIONAL COUNTIES SUNDAY EVENING AND KEPT THE ONES FOR WALSH AND GRAND FORKS COUNTIES UNTIL 600 PM CDT TUESDAY AS WELL. THIS WAS BASED ON REPORTS OF WATER OVER MANY RURAL ROADS AND RISES NOTED ON GAGES OF SMALLER STREAMS AND RIVERS. THE TURTLE RIVER NEAR ARVILLA IN WESTERN GRAND FORKS COUNTY IN PARTICULAR SHOWED A SIGNIFICANT RISE SUNDAY. WE ALSO HAVE AN AREAL FLOOD WATCH IN EFFECT THROUGH TUESDAY AFTERNOON IN THE PORTIONS OF THE DEVILS LAKE BASIN AND NORTHWEST AND WEST CENTRAL MINNESOTA WHERE THERE COULD STILL BE OVERLAND FLOODING ISSUES AND WHERE WE HAVE NOT UPGRADED TO WARNINGS. THERE IS POTENTIAL FOR THE RAINFALL MONDAY NIGHT AND EARLY TUESDAY TO CREATE AN INCREASE IN THE OVERLAND FLOOD POTENTIAL IN SOME AREAS. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...FLOOD WATCH THROUGH TUESDAY AFTERNOON FOR NDZ014-015-024-026-028. MN...FLOOD WATCH THROUGH TUESDAY AFTERNOON FOR MNZ004>006-008-009-013- 014-027-028-030>032. && $$ SHORT TERM...ROGERS LONG TERM...JR AVIATION...TG HYDROLOGY...CJS