Threats Assessment Discussion

217 
FXUS21 KWNC 241925
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT MARCH 24 2017
SYNOPSIS: DURING THE FIRST FEW DAYS OF THE OUTLOOK PERIOD, SEVERAL WAVES OF LOW 
PRESSURE ARE PREDICTED TO TRACK NORTHEASTWARD ALONG A COLD FRONT THAT IS 
INITIALLY FORECAST TO EXTEND FROM THE SOUTHERN PLAINS TO THE EASTERN GREAT 
LAKES REGION. THE FRONT IS EXPECTED TO STALL AS IT REACHES THE DEEP SOUTH 
SEVERAL DAYS LATER. ON MARCH 30TH, THIS FRONT IS ANTICIPATED TO BEGIN MOVING 
NORTHWARD AS A WARM FRONT, WHICH EXTENDS WESTWARD TO A DEVELOPING LOW PRESSURE 
CENTER OVER THE SOUTHERN PLAINS. THIS DEVELOPING LOW IS THEN FORECAST TO TRACK 
NORTHEASTWARD TOWARDS THE OHIO VALLEY AND EASTERN GREAT LAKES REGION. THE 
ANTICIPATED PASSAGE OF SEVERAL FRONTAL SYSTEMS ACROSS THE WEST DURING THIS 
OUTLOOK PERIOD IS EXPECTED TO BRING ADDITIONAL PRECIPITATION, ESPECIALLY TO THE 
PACIFIC NORTHWEST. IN ALASKA, SEVERAL AREAS OF WEAK LOW PRESSURE ARE PROJECTED 
TO INFLUENCE THE SOUTHERN PORTIONS OF THE STATE. A MORE SIGNIFICANT STORM 
SYSTEM MAY AFFECT THE ALEUTIANS AND ALASKA PENINSULA ABOUT A WEEK FROM NOW.
HAZARDS
SEVERE WEATHER FOR PARTS OF THE LOWER MISSISSIPPI AND LOWER TENNESSEE VALLEYS, 
MON, MAR 27.
SEVERE WEATHER FOR WEST-CENTRAL TEXAS AND NEARBY PARTS OF EXTREME SOUTHERN 
OKLAHOMA, TUE, MAR 28.
SEVERE WEATHER FOR EASTERN PORTIONS OF THE SOUTHERN PLAINS, AND THE LOWER 
MISSISSIPPI VALLEY, WED, MAR 29.
PERIODS OF LOCALLY HEAVY RAIN FOR CENTRAL AND SOUTHERN PORTIONS OF BOTH THE 
GREAT PLAINS AND MISSISSIPPI VALLEY, EXTENDING EASTWARD INTO ALABAMA, MON-THU, 
MAR 27-30.
MIXED PRECIPITATION (RAIN, FREEZING RAIN, SLEET AND SNOW) FOR MUCH OF NEW 
ENGLAND, MON, MAR 27.
HEAVY PRECIPITATION (RAIN AND MOUNTAIN SNOW) FOR THE PACIFIC NORTHWEST, 
MON-TUE, MAR 27-28.
FLOODING IS POSSIBLE, LIKELY OR IMMINENT/OCCURRING OVER PARTS OF THE PACIFIC 
NORTHWEST, NORTHERN AND CENTRAL INTERMOUNTAIN REGION, AND THE NORTHERN ROCKIES.
HEAVY RAIN FOR EASTERN PORTIONS OF BOTH OKLAHOMA AND TEXAS, AND THE LOWER 
MISSISSIPPI VALLEY, SAT-SUN, APR 1-2.
SLIGHT CHANCE OF MUCH ABOVE-NORMAL TEMPERATURES FROM THE LOWER MISSISSIPPI 
VALLEY EASTWARD TO THE SOUTHERN ATLANTIC COAST, SAT, APR 1.
SEVERE DROUGHT ACROSS PARTS OF ARIZONA, CALIFORNIA, THE CENTRAL AND SOUTHERN 
GREAT PLAINS, ARKANSAS, MISSOURI, AND THE EASTERN U.S.
DETAILED SUMMARY
FOR MONDAY MARCH 27 - FRIDAY MARCH 31: AT THE START OF THE PERIOD, A COLD FRONT 
IS PREDICTED TO STRETCH SOUTHWESTWARD FROM A LOW PRESSURE CENTER OVER THE 
EASTERN GREAT LAKES REGION TO THE SOUTHERN GREAT PLAINS. A WARM FRONT IS 
FORECAST TO EXTEND EASTWARD FROM THE SURFACE LOW ACROSS THE NORTHEAST CONUS. 
ANOTHER LOW PRESSURE CENTER IS INITIALLY PREDICTED ON THE COLD FRONT IN THE 
VICINITY OF THE OZARK MOUNTAINS. THIS COMPLEX FRONTAL SYSTEM IS ANTICIPATED TO 
BRING SEVERAL WEATHER-RELATED HAZARDS, THE MOST SERIOUS OF WHICH INCLUDES 
MULTIPLE SEVERE THUNDERSTORM OUTBREAKS ACROSS THE SOUTHERN PLAINS, LOWER 
MISSISSIPPI VALLEY, AND LOWER TENNESSEE VALLEY DURING A THREE-DAY PERIOD. 
CHRONOLOGICALLY, THE FIRST HIGHLIGHTED AREA OF SEVERE WEATHER IS APPLICABLE FOR 
THE LOWER MISSISSIPPI AND LOWER TENNESSEE VALLEYS ON MONDAY, MARCH 27TH. THE 
STORM PREDICTION CENTER (SPC) IN OKLAHOMA EXPECTS AN AXIS OF INSTABILITY NEAR 
THE SOUTHERN PORTION OF THE MISSISSIPPI RIVER, AND DEEP-LAYER WIND SHEAR 
ASSOCIATED WITH A BELT OF STRONGER 500-HPA FLOW ROUNDING THE BASE OF THE UPPER 
TROUGH. THESE CONDITIONS ARE THOUGHT TO BE SUFFICIENT FOR ISOLATED AREAS OF 
SEVERE WEATHER. ON TUESDAY, MARCH 28TH, LOW-LEVEL GULF MOISTURE IS ANTICIPATED 
TO STREAM NORTHWARD ACROSS THE SOUTHERN PLAINS AHEAD OF AN EASTWARD-ADVANCING 
DRYLINE. ISOLATED SEVERE WEATHER COVERAGE IS AGAIN ANTICIPATED DURING THE 
AFTERNOON, THIS TIME ACROSS WEST-CENTRAL TEXAS AND ADJACENT PARTS OF OKLAHOMA. 
THE SPATIAL COVERAGE OF SEVERE THUNDERSTORMS IS EXPECTED TO INCREASE LATE IN 
THE DAY AND EVENING AS THE 500-HPA LOW AND TROUGH APPROACH THE AREA. MODERATE 
INSTABILITY AND STRONG DEEP-LAYER SHEAR ARE FORECAST TO BE IN PLACE. IN 
ADDITION, A WELL-DEVELOPED LOW-LEVEL JET SHOULD MAINTAIN AN ORGANIZED SEVERE 
WEATHER THREAT LATE TUESDAY NIGHT INTO WEDNESDAY, MARCH 29TH. PREDICTED HAZARDS 
INCLUDE LARGE HAIL, WIND DAMAGE, AND SOME TORNADOES, AS AN EXPECTED SQUALL LINE 
ORGANIZES AND MOVES ACROSS THE SOUTHERN PLAINS FROM TUESDAY EVENING INTO 
WEDNESDAY AFTERNOON. PERIODS OF HEAVY RAINFALL ARE ALSO PREDICTED ACROSS 
CENTRAL AND SOUTHERN PORTIONS OF BOTH THE GREAT PLAINS AND MISSISSIPPI VALLEY, 
EXTENDING EASTWARD INTO ALABAMA, FROM MARCH 27-30. PRECIPITATION AMOUNTS DURING 
THIS 4-DAY PERIOD ARE EXPECTED TO RANGE FROM 2-6 INCHES.
EARLY IN THIS PERIOD, ON MARCH 27TH, THERE IS AN INCREASED RISK OF MIXED 
PRECIPITATION (RAIN, FREEZING RAIN, SLEET AND SNOW) FOR MUCH OF NEW ENGLAND, 
NORTH OF A PREDICTED WARM FRONT.
PACIFIC STORM SYSTEMS ARE FORECAST TO MOVE ACROSS THE WEST COAST STATES DURING 
THIS PERIOD. A HEAVY PRECIPITATION (RAIN AND MOUNTAIN SNOW) HAZARD IS POSTED 
FOR THE PACIFIC NORTHWEST FOR LIQUID EQUIVALENT PRECIPITATION AMOUNTS OF ABOUT 
2.0-3.5 INCHES.
FLOODING IS POSSIBLE, LIKELY, OR OCCURRING/IMMINENT ACROSS PARTS OF THE PACIFIC 
NORTHWEST, THE NORTHERN AND CENTRAL INTERMOUNTAIN REGION, AND THE NORTHERN 
ROCKIES. THIS IS DUE TO UNSEASONABLY WARM TEMPERATURES COUPLED WITH RAINFALL 
DURING MID-MARCH.
A SIGNIFICANT CYCLONIC SYSTEM MAY APPROACH THE ALEUTIANS AND ALASKA PENINSULA 
FROM THE SOUTHWEST LATE IN THIS PERIOD. HOWEVER, SUBSTANTIAL DISAGREEMENTS 
BETWEEN THE ECMWF AND GFS MODELS REGARDING THE FORECAST PATH OF THIS SYSTEM 
PRECLUDE THE SPECIFICATION OF HAZARDOUS AREAS ON THE MAP AT THIS TIME.
FOR SATURDAY APRIL 01 - FRIDAY APRIL 07: AN AREA OF HEAVY RAIN IS FORECAST OVER 
EASTERN PORTIONS OF BOTH OKLAHOMA AND TEXAS, AND OVER THE LOWER MISSISSIPPI 
VALLEY, FROM APRIL 1-2. THIS IS IN RESPONSE TO A 500-HPA TROUGH EXPECTED TO 
APPROACH THIS AREA FROM THE WEST. THERE IS ALSO THE POTENTIAL FOR STRONG TO 
SEVERE THUNDERSTORMS TO DEVELOP ONCE AGAIN IN THIS GENERAL AREA, BUT THERE IS 
NOT ENOUGH CONFIDENCE AT THIS TIME TO WARRANT THE DEPICTION OF A SEVERE WEATHER 
REGION.
ON APRIL 1ST, THERE IS A SLIGHT CHANCE (20-PERCENT) OF MUCH ABOVE-NORMAL 
TEMPERATURES FROM THE LOWER MISSISSIPPI VALLEY EASTWARD TO THE SOUTHERN 
ATLANTIC COAST. WITHIN THIS AREA, TEMPERATURES ARE EXPECTED TO REACH THE 85TH 
PERCENTILE (OR HIGHER) OF THE HISTORICAL DISTRIBUTION. FOR MOST AREAS, HIGH 
TEMPERATURES ARE FORECAST TO REACH THE MID-UPPER 80'S, WHILE A FEW LOCALES MAY 
PUSH 90 DEG F.
ACCORDING TO THE U.S. DROUGHT MONITOR RELEASED ON MARCH 23RD (USING DATA 
THROUGH 8AM EASTERN TIME, MARCH 21ST), CHANGES COMPARED TO THE PREVIOUS WEEK 
INCLUDED ONE-CLASS DEGRADATION ACROSS PARTS OF THE SOUTHERN TIER OF STATES FROM 
NEW MEXICO TO SOUTH CAROLINA, PARTS OF OKLAHOMA AND KANSAS, AND HAWAII. 
ONE-CLASS IMPROVEMENTS IN DROUGHT CATEGORY WERE PRIMARILY FOCUSED ON THE 
NORTHEAST AND MID-ATLANTIC, TENNESSEE, NORTHERN ALABAMA, AND EASTERN PORTIONS 
OF PUERTO RICO. NO CHANGES TO THE DROUGHT DEPICTION WERE MADE IN ALASKA. 
COVERAGE OF SEVERE, OR GREATER INTENSITY, DROUGHT THROUGHOUT THE CONUS 
DECREASED SLIGHTLY FROM 3.95 LAST WEEK TO 3.74 PERCENT THIS WEEK.
FORECASTER: ANTHONY ARTUSA 
$$