US HAZARDS OUTLOOK NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD 300 PM EST MARCH 10 2017 SYNOPSIS: EARLY IN THE FORECAST PERIOD A SURFACE LOW PRESSURE PASSING THROUGH THE MIDWEST IS ANTICIPATED TO PHASE WITH A COASTAL DISTURBANCE OFF THE CAROLINAS, WITH EXPLOSIVE DEVELOPMENT OF THE SUBSEQUENT SYSTEM JUST OFF THE MID-ATLANTIC COAST. SURFACE HIGH PRESSURE IS FORECAST TO SETTLE EAST OF THE MISSISSIPPI IN THE WAKE OF THIS SYSTEM. PERIODIC DISTURBANCES ARE POSSIBLE IN THE NORTHEAST PACIFIC THROUGHOUT WEEK-1, BUT THE STORM TRACK APPEARS TO HAVE BECOME FOCUSED OVER BRITISH COLUMBIA. SURFACE HIGH PRESSURE IS FORECAST TO SHIFT WESTWARD IN THE BERING SEA DURING WEEK-1 AND 2. DURING WEEK-2 OVER THE LOWER-48, MID-LEVEL HIGH PRESSURE IS FORECAST ACROSS THE WEST WITH MID-LEVEL LOW PRESSURE OVER NEW ENGLAND. HAZARDS HEAVY SNOW ACROSS PORTIONS OF THE NORTHEAST, THE CENTRAL APPALACHIANS, THE MID-ATLANTIC, THE SOUTHERN APPALACHIANS, AND THE OHIO VALLEY, MON-TUE, MAR 13-14. HEAVY RAIN ACROSS PORTIONS OF THE SOUTHEAST, THE MID-ATLANTIC, AND THE NORTHEAST, MON-TUE, MAR 13-14. HIGH WINDS ACROSS PORTIONS OF THE MID-ATLANTIC AND THE NORTHEAST, MON-WED, MAR 13-15. MUCH BELOW-NORMAL TEMPERATURES ACROSS PORTIONS OF THE NORTHEAST, THE CENTRAL APPALACHIANS, THE MIDDLE MISSISSIPPI VALLEY, THE MID-ATLANTIC, AND THE MIDWEST, MON-TUE, MAR 13-14. MUCH BELOW-NORMAL TEMPERATURES ACROSS PORTIONS OF THE NORTHERN PLAINS, THE CENTRAL PLAINS, AND THE UPPER MISSISSIPPI VALLEY, MON-TUE, MAR 13-14. MUCH BELOW-NORMAL TEMPERATURES ACROSS PORTIONS OF THE LOWER MISSISSIPPI VALLEY, THE CENTRAL APPALACHIANS, THE TENNESSEE VALLEY, THE MIDDLE MISSISSIPPI VALLEY, THE MID-ATLANTIC, THE SOUTHERN APPALACHIANS, THE SOUTHEAST, THE GREAT LAKES, AND THE OHIO VALLEY, WED-THU, MAR 15-16. MUCH BELOW-NORMAL TEMPERATURES ACROSS PORTIONS OF NORTHERN MAINLAND ALASKA, TUE-WED, MAR 14-15. MUCH BELOW-NORMAL TEMPERATURES ACROSS PORTIONS OF SOUTHWESTERN MAINLAND ALASKA, TUE-FRI, MAR 14-17. HEAVY PRECIPITATION ACROSS PORTIONS OF THE PACIFIC NORTHWEST, FRI, MAR 17. FLOODING LIKELY, OCCURRING, OR IMMINENT ACROSS PORTIONS OF THE NORTHERN GREAT BASIN. SLIGHT RISK OF MUCH BELOW-NORMAL TEMPERATURES FOR PORTIONS OF THE NORTHEAST, THE CENTRAL APPALACHIANS, THE MID-ATLANTIC, THE SOUTHERN APPALACHIANS, THE GREAT LAKES, AND THE OHIO VALLEY, SAT, MAR 18. SLIGHT RISK OF MUCH BELOW-NORMAL TEMPERATURES FOR ALL OF ALASKA WITH THE EXCEPTION OF THE SOUTHEAST AND PANHANDLE, SAT-FRI, MAR 18-24. MODERATE RISK OF MUCH BELOW-NORMAL TEMPERATURES FOR PORTIONS OF WESTERN MAINLAND ALASKA AND THE ALEUTIANS, SAT-SUN, MAR 18-19. HIGH RISK OF MUCH BELOW-NORMAL TEMPERATURES FOR PORTIONS OF SOUTHWESTERN MAINLAND ALASKA, SAT, MAR 18. SEVERE DROUGHT FOR PARTS OF CALIFORNIA, ARIZONA, THE GREAT PLAINS, THE MISSISSIPPI VALLEY, AND THE EASTERN U.S. DETAILED SUMMARY FOR MONDAY MARCH 13 - FRIDAY MARCH 17: THE PRIMARY WEATHER-MAKER FOR THE U.S. DURING WEEK-1 APPEARS TO BE THE POTENTIAL LATE-SEASON NOR'EASTER. MUCH BELOW-NORMAL TEMPERATURES (MINIMUM TEMPERATURE ANOMALIES OF -12 DEGREES F OR GREATER) ARE ANTICIPATED ACROSS THE NORTHEAST IN ADVANCE OF THE SYSTEM ON MAR 13-14, HELPING TO INCREASE SUBSEQUENT SNOWFALL ODDS DESPITE IT BEING MID-MARCH. MODEL GUIDANCE STILL CONSISTENTLY PHASES A DISTURBANCE PASSING THROUGH THE MIDWEST WITH A LOW PRESSURE OFF THE CAROLINAS, WITH RAPID DEEPENING OF THE SYSTEM IN THE ATLANTIC AS A LOW CLOSES OFF AT 500-HPA WITHIN THE LONGWAVE TROUGH. DESPITE THE BROADER SIMILARITIES, MODEL DIFFERENCES REMAIN AND ARE EXPECTED TO HEAVILY IMPACT PRECIPITATION TYPE FROM THE SYSTEM. THE DETERMINISTIC GFS HAS THE FURTHEST WEST TRACK, WITH 0 AND 6Z RUNS PLACING THE SYSTEM NEAR CAPE MAY BY 12Z ON MAR 14, WHILE THE 12Z RUN HAS THE SYSTEM OVER THE DELMARVA PENINSULA. THIS WESTERN TRACK APPEARS TIED TO THE MODEL SUFFERING FROM GRID-SCALE CONVECTIVE FEEDBACK ISSUES, WITH THIS APPARENT IN THE UNREASONABLY TIGHT LOW- AND MID-LEVEL VERTICAL MOTION FIELDS THAT PULL THE SURFACE CENTER TOO FAR TO THE WEST. THE 12Z GEFS HAS TRENDED WEST RELATIVE TO PRIOR RUNS AS WELL, WITH SOLUTIONS CLUSTERING FURTHER SOUTH AND ABOUT HALF OF MEMBERS STILL SUPPORTING MAJOR SNOW FOR THE I-95 CORRIDOR. THE 0Z AND 12Z GEM, 0Z GEPS, 0Z ECMWF/ECENS, AND 12Z DETERMINISTIC ECMWF FORECASTS FALL TO THE EAST OF THE LATEST GEFS SOLUTION, TRACKING THE SYSTEM FROM OFF THE OUTER BANKS THROUGH EAST OF CAPE COD WHICH WOULD YIELD THE HEAVIEST SNOW FOR MORE COASTAL AREAS WITH LIMITED AREAS CHANGING TO RAIN. IN GENERAL THE CANADIAN FORECASTS HAVE A WEAKER SYSTEM, WHILE THE EUROPEAN SOLUTIONS ARE AS STRONG, OR STRONGER THAN, THE GFS-BASED PREDICTIONS. IN TERMS OF ASSOCIATED HAZARDS WITH THIS SYSTEM, HEAVY SNOW (EXCEEDING 4 INCHES IN 24 HOURS, LOCALIZED TOTALS OF 1-2 FEET IN PREFERRED LOCATIONS WHERE ELEVATED CONVECTIVE INSTABILITY IS RELEASED WITHIN THE TROWAL REGION) IS FORECAST FROM CENTRAL VIRGINIA NORTHWARD THROUGH NEW ENGLAND ON MAR 13-14, APPROXIMATELY ALONG THE I-95 CORRIDOR. TO THE EAST, AN AREA OF HEAVY RAIN (1 INCH OR GREATER IN 24 HOURS) IS FORECAST CLOSER TO THE COAST FROM EASTERN NORTH CAROLINA THROUGH SOUTHEASTERN MASSACHUSETTS FOR MAR 13-14. HIGH WINDS (IN EXCESS OF 35 KT) ARE ALSO ANTICIPATED WITH THE DEEPENING SYSTEM, SPANNING COASTAL AREAS FROM THE DELMARVA PENINSULA THROUGH MAINE FOR MAR 13-15. ANOTHER ROUND OF MUCH BELOW-NORMAL TEMPERATURES IS FORECAST FOR THE MIDWEST AND MID-ATLANTIC THROUGH THE SOUTHEAST ON MAR 15-16 ASSOCIATED WITH THE NORTHERLY WINDS IN THE WAKE OF THE NOR'EASTER AND BEHIND THE MID-LEVEL TROUGH. THE ANOMALOUS COLD OVER THE EAST LATE IN WEEK-1 IS ALSO ASSOCIATED WITH SURFACE HIGH PRESSURE ANTICIPATED TO BE SETTLING INTO THE CENTRAL PLAINS NEAR THE OUTSET OF THE PERIOD. THE CORE OF THIS HIGH PRESSURE IS ANTICIPATED TO DRIVE A REGION OF MUCH BELOW-NORMAL TEMPERATURES SHIFTING SOUTHEASTWARD FROM THE NORTHERN PLAINS INTO THE MIDDLE MISSISSIPPI VALLEY FOR MAR 13-14. A 500-HPA TROUGH CONTINUES TO BE FORECAST IN THE NORTHEAST PACIFIC DURING WEEK-1, DOWNSTREAM OF THE BLOCKING HIGH OFF THE RUSSIAN COAST. PERIODIC SHORTWAVES ARE FORECAST TO PASS AROUND THE TROUGH, BUT MUCH OF THE ENERGY IS FAVORED TO IMPACT BRITISH COLUMBIA INSTEAD OF U.S. INTERESTS. THE GEFS/ECENS INDICATE A CHANCE FOR ONE OF THESE FEATURES TO YIELD HEAVY PRECIPITATION (2" OR GREATER LIQUID EQUIVALENT, WITH SNOW IN THE NORTHERN CASCADES AND RAIN ELSEWHERE) FOR WESTERN OREGON AND WASHINGTON STATE ON MAR 17. A NORTHERLY COMPONENT TO THE LOW-LEVEL FLOW IS ANTICIPATED OVER MUCH OF ALASKA DURING WEEK-1 AS SURFACE HIGH PRESSURE IN THE BERING SEA IS FORECAST TO RETROGRADE. GIVEN THIS PATTERN, MUCH BELOW-NORMAL TEMPERATURES (MINIMUM TEMPERATURE ANOMALIES OF -20 DEGREES F OR GREATER) ARE FAVORED TO THE NORTH OF THE BROOKS RANGE FOR MAR 14-15 AND TO THE NORTH AND WEST OF THE ALASKA RANGE ON MAR 14-17 AS ANOMALOUSLY COLD AIR POOLS AGAINST THE TOPOGRAPHY. FOR SATURDAY MARCH 18 - FRIDAY MARCH 24: THE 500-HPA PATTERN DURING WEEK-2 OVER THE CONUS FAVORS A RIDGE ACROSS THE WEST AND TROUGHING OVER NEW ENGLAND. POSITIVE 500-HPA HEIGHT ANOMALIES ARE DISPLACED FURTHER EAST BY THE ECENS AND GEPS ACROSS THE CENTRAL PLAINS RELATIVE TO THE GFS AND GEFS WHICH ARE MORE FOCUSED OVER THE SOUTHWEST. 500-HPA TROUGHING AND NEGATIVE HEIGHT ANOMALIES ARE FORECAST ACROSS ALASKA IN WEEK-2. A SLIGHT RISK OF MUCH BELOW-NORMAL TEMPERATURES IS POSSIBLE FROM EASTERN NORTH CAROLINA THROUGH MAINE ON MAR 18 AS SOME RESIDUAL COLD MAY LINGER FROM WEEK-1. ONCE MORE THE PRIMARY FOCUS FOR MUCH BELOW-NORMAL CHANCES DURING WEEK-2 APPEARS TO BE ALASKA. THE GEFS PROBABILISTIC EXTREMES TOOL INDICATES A HIGH (60%), MODERATE (40%), AND SLIGHT (20%) RISKS OF MUCH BELOW-NORMAL TEMPERATURES FOR THE STATE, WITH HIGHEST PROBABILITIES FOCUSED ACROSS THE SOUTHWESTERN AND WESTERN PORTIONS OF THE STATE DURING THE FIRST PART OF WEEK-2. THE SLIGHT RISK OF MUCH BELOW-NORMAL TEMPERATURES HAZARD COVERS THE ENTIRE STATE WITH THE EXCEPTION OF SOUTHEASTERN MAINLAND ALASKA AND THE ALASKA PANHANDLE THROUGHOUT WEEK-2. TODAY'S ECENS REFORECAST GUIDANCE IS MORE MODERATE THAN RECENT DAYS WITH ALASKAN TEMPERATURES, WHILE THE GEFS CONTINUES TO SUPPORT STRONG COLD SIGNALS IN THE SOUTHWESTERN PART OF THE STATE. ACCORDING TO THE U.S. DROUGHT MONITOR VALID ON MARCH 7, SEVERE DROUGHT IS DESIGNATED ACROSS PARTS OF CALIFORNIA, ARIZONA, THE GREAT PLAINS, THE MISSISSIPPI VALLEY, AND THE EASTERN U.S. COVERAGE OF SEVERE, OR GREATER INTENSITY, DROUGHT THROUGHOUT THE CONUS INCREASED FROM 3.68 TO 4 PERCENT. IMPROVEMENT IN PARTS OF THE SOUTHWEST WAS OFFSET BY DETERIORATION ACROSS THE PLAINS AND MIDDLE AND LOWER MISSISSIPPI VALLEY. FORECASTER: CPC FORECASTER $$