Threats Assessment Discussion

098 
FXUS21 KWNC 162001
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT OCTOBER 16 2018
SYNOPSIS: A STATIONARY FRONT IS PREDICTED TO STRETCH FROM A SURFACE LOW OFF THE 
SOUTH TEXAS COAST EASTWARD ACROSS THE NORTHERN GULF OF MEXICO AND THE FLORIDA 
PENINSULA THROUGHOUT THE 3-7 DAY PERIOD. MEANWHILE, A SERIES OF COLD FRONTS ARE 
PREDICTED TO SLIDE SOUTHEASTWARD OUT OF CANADA ACROSS THE CENTRAL AND EASTERN 
CONUS. BACK TO BACK STORM SYSTEMS ARE PREDICTED TO IMPACT PARTS OF THE SOUTH 
COAST OF ALASKA AND THE NORTHERN ALASKA PANHANDLE DURING THE 3-7 DAY PERIOD. 
MID-LEVEL LOW PRESSURE IS ANTICIPATED TO DOMINATE THE EASTERN HALF OF THE 
CONUS, ALEUTIANS, AND SOUTH COAST OF ALASKA DURING WEEK-2, WITH MID-LEVEL HIGH 
PRESSURE ELSEWHERE.
HAZARDS
PERIODS OF HEAVY RAIN ACROSS PORTIONS OF EASTERN TEXAS, FRI-TUE, OCT 19-23.
PERIODS OF HEAVY RAIN AND HIGH ELEVATION SNOW ACROSS PARTS OF THE SOUTH COAST 
OF ALASKA, AND THE ALASKA PANHANDLE, FRI-MON, OCT 19-22.
MUCH BELOW NORMAL TEMPERATURES ACROSS PRIMARILY INTERIOR PORTIONS OF THE 
NORTHEAST AND MID-ATLANTIC, AND THE UPPER OHIO VALLEY, FRI, OCT 19.
HIGH WINDS ACROSS THE GREAT LAKES REGION, FRI-SAT, OCT 19-20.
PERIODS OF HIGH WINDS ACROSS THE SOUTH COAST OF ALASKA AND THE NORTHERN 
PANHANDLE, FRI-MON, OCT 19-22.
HIGH SIGNIFICANT WAVE HEIGHTS FOR COASTAL PORTIONS OF SOUTH-CENTRAL ALASKA, 
FRI-MON, OCT 19-22.
FLOODING POSSIBLE, LIKELY, IMMINENT/OCCURRING OVER TEXAS, EASTERN KANSAS, THE 
MIDDLE AND UPPER MISSISSIPPI VALLEY, SOUTHERN VIRGINIA, AND PARTS OF THE 
SOUTHEAST.
SLIGHT RISK OF MUCH BELOW NORMAL TEMPERATURES FOR PORTIONS OF THE CONUS EAST OF 
THE MISSISSIPPI RIVER, WED-FRI, OCT 24-26.
SLIGHT RISK OF HEAVY PRECIPITATION FROM THE SOUTHERN PLAINS EASTWARD TO THE 
SOUTH ATLANTIC COAST, WED-SUN, OCT 24-28.
MODERATE RISK OF HEAVY PRECIPITATION FOR MOST OF THE GULF COAST REGION, 
WED-SUN, OCT 24-28.
SEVERE DROUGHT ACROSS THE PLAINS, THE ROCKIES, THE NORTHEAST, THE GREAT BASIN, 
THE PACIFIC COAST STATES, MISSOURI, AND THE ALASKA PANHANDLE.
DETAILED SUMMARY
FOR FRIDAY OCTOBER 19 - TUESDAY OCTOBER 23: A MID-LEVEL TROUGH OVER THE FOUR 
CORNERS REGION IS FORECAST TO STEER EASTERN PACIFIC MOISTURE FROM TROPICAL 
STORM TARA INTO THE SOUTHERN PLAINS AND LOWER MISSISSIPPI VALLEY EARLY IN THIS 
PERIOD. SURFACE LOW PRESSURE NEAR THE SOUTH TEXAS COAST AND AN ACCOMPANYING 
STATIONARY FRONT OVER THE NORTHERN GULF OF MEXICO ARE PREDICTED TO BRING 
PERIODS OF HEAVY RAIN (1.5-4.0 INCHES, OCT 19-22) TO PORTIONS OF EAST TEXAS, 
BUT ESPECIALLY CLOSE TO THE SOUTH TEXAS COAST. IN FACT, MOST OF THE ANTICIPATED 
RAINFALL IS EXPECTED TO BE CLOSE TO, OR JUST OFF THE COAST. THIS RAIN MAY 
EXACERBATE OR PROLONG AREAS ALREADY IMPACTED BY FLOODING IN THE SOUTHERN PLAINS.
AN AMPLIFYING MID-LEVEL TROUGH OVER THE EASTERN CONUS FAVORS MUCH BELOW NORMAL 
TEMPERATURES FOR MOSTLY INTERIOR PORTIONS OF THE NORTHEAST, MID-ATLANTIC, AND 
UPPER OHIO VALLEY ON OCT 19. EVEN THOUGH MINIMUM TEMPERATURE ANOMALIES MAY ONLY 
REACH 8-10 DEG F COMPARED TO NORMAL, THE HIGHLIGHTED REGION DEPICTS WHERE AREAS 
MAY EXPERIENCE THEIR FIRST FROST OF THE SEASON. A SURFACE LOW OVER EASTERN 
CANADA AND ITS ASSOCIATED TRAILING COLD FRONTS MAY BRING HIGH WINDS (20-25 
KNOTS OR GREATER) TO PARTS OF THE GREAT LAKES REGION,  OCT 19-20. THOUGH 
TEMPERATURES ARE STILL RELATIVELY WARM NOW, THE PASSAGE OF THESE COLDER AIR 
MASSES IS FORECASTED TO BRING THE FIRST LAKE-EFFECT SNOWFALL OF THE SEASON TO 
SOME DOWNWIND LOCATIONS, THOUGH SNOWFALL AMOUNTS ARE FORECAST TO BE ON THE 
LIGHTER SIDE.
BACK TO BACK SURFACE LOWS ARE PREDICTED TO IMPACT THE SOUTH COAST OF ALASKA AND 
THE PANHANDLE REGION THROUGHOUT THE 3-7 DAY PERIOD. PERIODS OF HEAVY 
PRECIPITATION (LOW ELEVATION RAIN AND MOUNTAIN SNOW, 3 INCHES OR MORE LIQUID 
EQUIVALENT), STRONG WINDS (40 KNOTS OR GREATER) AND HIGH SIGNIFICANT WAVE 
HEIGHTS (20-25 FEET OR MORE) ARE FAVORED, AS DEPICTED ON THE MAP.
FOR WEDNESDAY OCTOBER 24 - TUESDAY OCTOBER 30: CONTINUED MID-LEVEL TROUGHING 
AND RENEWED SURGES OF COLDER AIR NEAR THE SURFACE OVER THE EASTERN CONUS FAVOR 
A SLIGHT CHANCE OF MUCH BELOW NORMAL TEMPERATURES FOR MANY AREAS EAST OF THE 
MISSISSIPPI RIVER, OCT 24-26. THIS IS WHERE THE GEFS REFORECAST TOOL IDENTIFIES 
A 20% CHANCE OR GREATER OF TEMPERATURES REACHING THE 15TH PERCENTILE OR LOWER 
OF THE HISTORICAL DISTRIBUTION. FREEZING TEMPERATURES ARE MORE LIKELY FOR THE 
OHIO VALLEY AND NORTHWARD, WHILE TEMPERATURES ACROSS THE TENNESSEE VALLEY, 
LOWER MISSISSIPPI VALLEY, AND SOUTHEAST ARE FORECAST TO REACH 40 DEG F OR 
COLDER.
SLIGHT AND MODERATE RISKS FOR HEAVY PRECIPITATION (20% AND 40%, RESPECTIVELY) 
ARE PREDICTED FROM THE SOUTHERN PLAINS EASTWARD ACROSS THE GULF COAST STATES TO 
THE SOUTH ATLANTIC COAST, OCT 24-28. THESE AREAS DEPICT, IN GENERAL, WHERE THE 
GEFS AND ECMWF FORECAST TOOLS AGREE ON PRECIPITATION AMOUNTS REACHING THE 85TH 
PERCENTILE DURING THIS PERIOD (OCT 24-28), AND ALSO WHERE AT LEAST 2 INCHES IS 
FAVORED. THIS REGION IS ALSO OUT AHEAD OF A PREDICTED SOUTHERN STREAM 500-HPA 
TROUGH, AND ASSOCIATED WITH LOW SURFACE PRESSURE AND A MEAN BAROCLINIC ZONE 
OVER THE GULF OF MEXICO.
THE U.S. DROUGHT MONITOR, VALID OCTOBER 9TH, INDICATES A DECREASE IN SEVERE TO 
EXCEPTIONAL DROUGHT (D2 TO D4) COVERAGE FROM 17.03% TO 14.40% DURING THE PAST 
WEEK. SOME IMPROVEMENT IN DROUGHT CONDITIONS WAS NOTED OVER PARTS OF EASTERN 
KANSAS, MISSOURI, WEST TEXAS, AND UTAH. SOME DETERIORATION WAS NOTED IN PARTS 
OF THE NORTHERN PLAINS. NO CHANGES IN THE DROUGHT DEPICTION WERE RENDERED TO 
ALASKA OR PUERTO RICO. A SMALL AREA OF D0 WAS REMOVED OVER HAWAII.
FORECASTER: ANTHONY ARTUSA 
$$