FXUS63 KBIS 180853 AFDBIS AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BISMARCK ND 353 AM CDT THU MAR 18 2010 .SHORT TERM...TODAY THROUGH SATURDAY NIGHT... FORECAST CONCERNS TODAY CONTINUE WITH SNOW MELT AND HYDROLOGIC ISSUES...AND GUSTY WINDS ACROSS NORTH CENTRAL THIS AFTERNOON. COLDER TEMPERATURES FRIDAY AND INTO THE WEEKEND WILL SLOW THE MELTING PROCESS...ESPECIALLY AT NIGHT WITH LOWS DROPPING INTO THE TEENS. FOR TODAY...A COLD FRONT WILL SWEEP FROM NORTH TO SOUTH WITH GUSTY NORTHWEST WINDS TO FOLLOW BEHIND THE FRONT. THE GUSTY WINDS WILL IMPACT NORTHERN NORTH DAKOTA LATE THIS MORNING AND THROUGH THE AFTERNOON WITH 25 TO 35 MPH. WITH THE FRONT PASSING OVER CENTRAL AND SOUTHERN NORTH DAKOTA LATER THIS AFTERNOON...WINDS WILL NOT BE AS GUSTY THIS EVENING/TONIGHT BUT STILL BRISK AT 15 TO 25 MPH. ISOLATED RAIN AND SNOW SHOWERS WILL ACCOMPANY THE FRONT. HOWEVER NO SIGNIFICANT PRECIPITATION IS EXPECTED THROUGH THE SHORT TERM. THE LATEST WATER VAPOR SHOWS GENERALLY A ZONAL FLOW ACROSS THE NORTHERN HIGH PLAINS WITH AN UPSTREAM LOW/UPPER TROUGH NOW MOVING THROUGH CENTRAL SASKATCHEWAN TRAILING BACK INTO MONTANA. A 90KT 300 MB JET WAS LOCATED OVER NORTHEASTERN MONTANA. THE RIGHT ENTRANCE REGION OF THE JET WAS SUPPORTING SOME LIGHT PRECIPITATION OVER EASTERN MONTANA AS EVIDENT ON THE REGIONAL RADAR...HOWEVER MOST OF THIS WAS NOT REACHING THE GROUND AT THIS TIME. MID LEVEL OVERCAST CLOUDS WERE ALREADY SPREADING OVER WESTERN NORTH DAKOTA AND EXPECT THIS TREND TO CONTINUE THROUGH THE CWA THIS MORNING AND INTO THE AFTERNOON. THE UPPER TROUGH WAS SUPPORTING A SURFACE LOW PRESSURE AND COLD FRONT OVER SOUTH CENTRAL SASKATCHEWAN. MODELS IN GOOD AGREEMENT IN MOVING THE LOW SOUTHEAST AND CONCUR GIVEN THE GREATEST PRESSURE FALLS ARE OCCURRING TO THE EAST AND SOUTHEAST PER MSAS. THE COLD FRONT WILL MOVE THROUGH THE NORTH CENTRAL ZONES BETWEEN 12Z AND 18Z TODAY...THEN ACROSS SOUTH CENTRAL NORTH DAKOTA BETWEEN 18Z- 00Z. AS MENTIONED ABOVE GUSTY NORTHWEST WINDS WILL ACCOMPANY THE PASSAGE OF THE FRONT WHICH WILL CONTINUE INTO TONIGHT. WITH THE AFOREMENTIONED JETSTREAK MOVING INTO NORTHERN NORTH DAKOTA THIS AFTERNOON AND INTO MINNESOTA THIS EVENING...THAT COMBINED WITH THE SURFACE FRONT DROPPING SOUTH THROUGH THE STATE TODAY WILL GENERATE ENOUGH CONVERGENCE AND SUBSEQUENT LIFT TO PRODUCE ISOLATED RAIN/SNOW SHOWERS THIS MORNING THEN ISOLATED RAIN SHOWERS THIS AFTERNOON. TEMPERATURES WILL BE COOLER TODAY ACROSS THE NORTH WITH AN EARLIER FRONTAL PASSAGE...HOWEVER MOST OF SOUTH CENTRAL AND SOUTHWEST NORTH DAKOTA WILL ACTUALLY EXPERIENCE NEARLY AS HIGH OR POSSIBLY SLIGHTLY HIGHER TEMPERATURES THAN WEDNESDAY AS MIXING IN THE BOUNDARY LAYER INCREASES DURING THE DAY AND WEAKENS/ERODES THE PERSISTENT INVERSION ALOFT...HELPING TO MIX DOWN SOME OF THE MILDER AIR BEFORE THE COLD FRONT ARRIVES. OVERALL THOUGH EXPECT HIGH TEMPERATURES IN THE LOW TO MID 40S ACROSS THE NORTH AND MID/UPPER 40S ACROSS THE SOUTHWEST AND SOUTH CENTRAL. ZONAL FLOW QUICKLY TRANSITIONS TOWARD NORTHWEST FLOW TONIGHT RESULTING IN STRONG COLD AIR ADVECTION FIRMLY TAKING CONTROL. CROSS SECTIONS SUPPORT A MOISTENING BOUNDARY LAYER TONIGHT INTO FRIDAY AND THIS IS SUPPORTED BY CURRENT SATELLITE IMAGERY AND SURFACE OBSERVATIONS BEHIND THE FRONT IN SASKATCHEWAN. THUS EXPECT RAIN/SNOW SHOWERS BECOMING JUST ISOLATED SNOW SHOWERS TONIGHT AND FRIDAY. HIGHS ON FRIDAY WILL BE NOTICEABLY COLDER WITH HIGHS ONLY IN THE LOWER 30S AND BRISK NORTHWEST WINDS BETWEEN 10 AND 20 MPH. THE UPPER TROUGH SLIDES THROUGH FRIDAY NIGHT WHICH WILL END THE THREAT OF PRECIPITATION. NORTHWEST FLOW CONTINUES THROUGH SATURDAY NIGHT WITH LOW/MID LEVEL WARM AIR ADVECTION INITIATES AS BROAD RIDGING MOVES INTO CENTRAL MONTANA BY 12Z SUNDAY. EXPECT DRY WEATHER SATURDAY AND SATURDAY NIGHT. SLIGHTLY MILDER SATURDAY THAN FRIDAY WITH HIGH TEMPERATURES BETWEEN 35 AND 40F. LOWS SATURDAY NIGHT INTO EARLY SUNDAY MORNING WILL RANGE FROM THE UPPER TEENS TO AROUND 20F. .LONG TERM...SUNDAY THROUGH WEDNESDAY NIGHT... A HIGHLY AMPLIFIED PATTERN WILL BE IN PLACE OVER THE CONUS TO START THE LONG TERM WITH A RIDGE OVER THE WESTERN CONUS AND A SPRAWLING TROUGH IN THE VICINITY OF THE HUDSON BAY. A WEAK DISTURBANCE MOVING THROUGH THE FLOW GRAZES NORTH DAKOTA ON SUNDAY ALLOWING SOME COOLER AIR TO SPILL SOUTHWARD. A TROUGH MOVING INTO THE PACIFIC NORTHWEST WILL BEGIN TO FLATTEN THE WESTERN CONUS RIDGE AND KICK IT EASTWARD. THIS WILL SIGNAL A CHANGE TO A MORE ACTIVE PATTERN FOR NEXT WEEK. MODELS BEGIN TO DISAGREE QUICKLY WITH THE INTERACTION OF THE PACIFIC NORTHWEST TROUGH THE TROUGHING IN THE HUDSON BAY. THE GFS DROPS THE UPPER LEVEL LOW OVER THE HUDSON BAY SOUTHWARD WHICH FORCES THE PACIFIC NORTHWEST TROUGH AND ITS ENERGY FARTHER TO THE SOUTH. THE ECMWF DOES NOT DROP THE HUDSON BAY TROUGH AS FAR TO THE SOUTH ALLOWING ENERGY FROM THE PACIFIC NORTHWEST TO MOVE THROUGH NORTH DAKOTA. BOTH MODELS INDUCE A SURFACE LOW IN THE CENTRAL PLAINS AS THE ENERGY CROSSES THE ROCKIES WITH THE GFS PRODUCING A SURFACE LOW OVER CO/TX AND THE ECMWF PLACES THE LOW OVER SD/NE. THIS HAS BIG FORECAST IMPLICATION FOR WESTERN AND CENTRAL NORTH DAKOTA. THE ECMWF SCENARIO WOULD BRING MORE WIDESPREAD PRECIPITATION TO THE REGION MONDAY INTO TUESDAY WHILE THE GFS SOLUTION WOULD INDICATE A LOWER CHANCE OF PRECIPITATION. BOTH MODELS THEN MOVE A SECOND DISTURBANCE THROUGH THE NORTHERN PLAINS ON WEDNESDAY WITH DIFFERENCES IN THE STRENGTH. THE GFS SYSTEM IS SLIGHTLY STRONGER WITH MORE PRECIPITATION. HAVE OPTED TO EXPAND SLIGHT CHANCE POPS MONDAY INTO TUESDAY...AND CONTINUE THEM INTO WEDNESDAY...BUT FORECAST CONFIDENCE CONTINUES TO BE LOW THIS PERIOD. && .AVIATION... A SHORTWAVE MOVES THROUGH THE STATE THIS AFTERNOON AND PUSHES A SURFACE TROUGH THROUGH THE REGION WITH A WEAK WIND SHIFT FROM WEST TO NORTHWEST THURSDAY EVENING. WINDS INCREASE AGAIN THIS AFTERNOON ESPECIALLY AT KISN AND KMOT WITH WINDS OCCASIONAL GUSTING ABOVE 25 MPH. WINDS AT KIDK...KBIS...AND KJMS ARE EXPECTED TO BE IN THE 10 TO 20 MPH RANGE CURRENTLY...LOCAL RADARS ARE SHOWING SOME RETURNS BUT OBSERVATIONS INDICATE THAT THEY ARE MAINLY MID LEVEL CLOUDS AND VIRGA. THIS IS EXPECTED TO MOVE OUT OF THE REGION BY MID MORNING. && .HYDROLOGY... AS OF THURSDAY MORNING...RIVER LEVELS CONTINUE TO RISE ACROSS SOUTHERN PORTIONS OF WESTERN AND CENTRAL NORTH DAKOTA. WITH THE WARMER TEMPERATURES EXPERIENCED WEDNESDAY...THE WATERSHEDS HAD STANDING WATER MOVING TOWARDS SMALL STREAMS AND RIVERS. THESE INCLUDE APPLE CREEK NEAR MENOKEN... BEAVER CREEK NEAR LINTON...THE CANNONBALL NEAR BREIEN...THE LITTLE MISSOURI NEAR MARMARTH...THE JAMES AND KNIFE RIVERS AND PIPESTEM CREEK AREAS. RECENT SNOW MELT HAS RESULTED IN RAPID RISES THE LAST COUPLE OF DAYS IN THE APPLE CREEK BASIN. A RIVER FLOOD WARNING REMAINS IN EFFECT FOR BEAVER CREEK NEAR LINTON...WITH MAJOR FLOODING FORECAST. EARLY THURSDAY MORNING BEAVER CREEK STOOD AT 12.61 FEET. MAJOR FLOOD STAGE IS 13 FEET. AN ONGOING ICE JAM NEAR THE SENSOR BEGAN WEDNESDAY EVENING AND LATEST HYDROGRAPH TIME SERIES CONTINUE TO SHOW A FAST TREND UPWARDS TOWARDS MAJOR FLOODING. CURRENT FORECASTS SHOW THE RIVER RISING INTO MAJOR FLOOD STAGE THURSDAY AFTERNOON. A RIVER FLOOD WARNING REMAINS IN EFFECT FOR THE JAMES RIVER NEAR LUDDEN DAM. THE CURRENT STAGE EARLY THURSDAY MORNING WAS 12.47 FEET. THE RIVER LEVEL IS FORECAST TO RISE TO THE MODERATE FLOOD CATEGORY OF 14.0 FEET FRIDAY AFTERNOON...THEN CONTINUE SLOW RISES IN THE MODERATE CATEGORY THEREAFTER. A RIVER FLOOD WARNING REMAINS IN EFFECT FOR THE JAMES RIVER AT LAMOURE. THE CURRENT STAGE EARLY THURSDAY MORNING WAS 13.38 FEET. FLOOD STAGE IS 14 FEET. THE RIVER IS FORECAST TO REACH FLOOD STAGE THURSDAY MORNING. MODERATE FLOODING IS FORECAST TO OCCUR FRIDAY NIGHT. A RIVER FLOOD WATCH REMAINS IN EFFECT FOR APPLE CREEK IN BURLEIGH COUNTY. NO FLOODING IS CURRENTLY OBSERVED AT MENOKEN...BUT MINOR FLOODING IS POSSIBLE OVER THE WEEKEND. FORECASTS RISE THE CREEK TO NEAR 15 FEET BY SATURDAY MORNING. ADDITIONALLY...OVERLAND FLOODING ALONG THE APPLE CREEK IN BURLEIGH COUNTY IS POSSIBLE. A RIVER FLOOD WATCH CONTINUES FOR THE JAMES RIVER NEAR GRACE CITY AFFECTING FOSTER COUNTY. THE CURRENT STAGE EARLY THURSDAY MORNING WAS 7.88 FEET. FLOOD STAGE IS 12 FEET. CONTINUED RUNOFF FROM MELTING SNOW WILL RESULT IN THE RIVER TO REACH FLOOD STAGE EARLY FRIDAY MORNING. MAJOR FLOODING IS POSSIBLE SATURDAY AFTERNOON AS THE RIVER COULD RISE TO AROUND 15 FEET. A RIVER FLOOD WATCH CONTINUES FOR THE PIPESTEM CREEK NEAR PINGREE AFFECTING STUTSMAN COUNTY. THE CURRENT STAGE EARLY THURSDAY MORNING WAS 8.38 FEET. FLOOD STAGE IS 9.0 FEET. MINOR FLOODING IS FORECAST THURSDAY NIGHT AND CRESTING AT 9.3 FEET SATURDAY THROUGH SUNDAY. A FLOOD WARNING FOR OVERLAND FLOODING IS IN EFFECT FOR DICKEY...LAMOURE...MCINTOSH AND LOGAN COUNTIES IN SOUTH CENTRAL NORTH DAKOTA. WEDNESDAY AFTERNOON...EMERGENCY MANAGERS REPORTED OVERLAND FLOODING. SEVERAL ROADS HAVE BEEN WASHED OUT OR CLOSED DUE TO BLOCKED CULVERTS AND OVERFLOWING STREAM SYSTEMS. HIGH TEMPERATURES WILL BE IN THE MID 40S THURSDAY WHICH WILL ACCELERATE SNOW MELT. A COLD FRONT WILL SWEEP THROUGH LATE THURSDAY AFTERNOON RESULTING IN COLDER TEMPERATURES FOR FRIDAY WITH HIGHS RANGING BETWEEN 30 TO 35. OVERNIGHT LOW TEMPERATURES WILL RANGE BETWEEN 20 AND 25 FRIDAY MORNING...THEN LOWS BETWEEN 15 AND 20 ARE FORECAST OVER THE WEEKEND. THIS SHOULD ACT TO SLOW THE RATE OF MELTING CONSIDERABLY. A FLOOD WATCH IS IN EFFECT FOR OVERLAND AND RIVER FLOODING POTENTIAL IN SOUTHWEST AND SOUTH CENTRAL NORTH DAKOTA. THE PRIMARY CONCERN IS OVERLAND FLOODING DUE TO SNOWMELT RUNOFF ENCOUNTERING PLUGGED CULVERTS AND SURFACE DRAINAGES...WHICH MAY CAUSE WATER TO TOP LOCAL ROADWAYS. RIVERS AND CREEKS ACROSS NORTHERN NORTH DAKOTA HAVE NOT SHOWN MUCH RESPONSE TO THE ONGOING SNOW MELT. AS A RESULT...A FLOOD WATCH HAS NOT BEEN ISSUED FOR THIS PORTION OF THE CWA. HOWEVER...THIS AREA WILL HAVE TO BE MONITORED OVER THE NEXT FEW DAYS. && .BIS WATCHES/WARNINGS/ADVISORIES... FLOOD WATCH THROUGH FRIDAY EVENING FOR NDZ018>023-025-031>037- 040>046. && $$ SHORT TERM/HYDROLOGY...KS LONG TERM...AVIATION...DC/RK