Prognostic Meteorological Discussion
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FXUS21 KWNC 272015
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EST FEBRUARY 27 2017

SYNOPSIS: EARLY IN THE PERIOD, A SERIES OF SURFACE LOW-PRESSURE SYSTEMS ARE
FORECAST TO MOVE ACROSS THE NORTHERN TIER OF THE U.S. SURFACE LOW PRESSURE IS
FORECAST TO PASS NORTH OF NORTHEAST MAINLAND ALASKA AS ITS TRAILING COLD FRONT
MOVES OVER THE REGION MAR 2-3. ANOTHER AREA OF SURFACE LOW PRESSURE IS EXPECTED
NEAR THE ALASKA PANHANDLE ON THOSE SAME DATES. COLD SURFACE HIGH PRESSURE IS
FORECAST TO DOMINATE MUCH OF THE REST OF MAINLAND ALASKA AND THE ALEUTIANS INTO
THE WEEK-2 PERIOD.

HAZARDS

PERIODS OF HEAVY SNOW FOR PARTS OF THE OLYMPICS AND CASCADES, THU-SAT, MAR 2-4.

PERIODS OF HEAVY SNOW FOR PARTS OF THE BITTERROOTS AND NORTHERN ROCKIES,
FRI-SUN, MAR 3-5.

HEAVY PRECIPITATION FOR PARTS OF NORTHERN CALIFORNIA AND WESTERN OREGON,
SAT-SUN, MAR 4-5.

PERIODS OF MUCH BELOW NORMAL TEMPERATURES FOR PARTS OF CENTRAL AND SOUTHERN
MAINLAND ALASKA AND THE ALASKA PANHANDLE, THU-MON, MAR 2-6.

HIGH WINDS FOR PARTS OF NORTHEAST MAINLAND ALASKA, THU-FRI, MAR 2-3.

HEAVY SNOW FOR PARTS OF THE SOUTHERN ALASKA PANHANDLE, THU-FRI, MAR 2-3.

FLOODING OCCURRING OR IMMINENT, LIKELY, OR POSSIBLE ACROSS PORTIONS OF THE
GREAT LAKES, THE MISSISSIPPI VALLEY, THE NORTHERN AND CENTRAL PLAINS AND THE
NORTHERN GREAT BASIN.

SLIGHT RISK OF MUCH BELOW NORMAL TEMPERATURES FOR MUCH OF THE ALASKA PANHANDLE,
MAINLAND ALASKA, AND THE ALEUTIANS, TUE-MON, MAR 7-MAR 13.

MODERATE RISK OF MUCH BELOW NORMAL TEMPERATURES FOR MOST OF MAINLAND ALASKA AND
THE ALEUTIANS, TUE-SAT, MAR 7-MAR 11.

HIGH RISK OF MUCH BELOW NORMAL TEMPERATURES FOR PARTS OF SOUTHERN AND CENTRAL
MAINLAND ALASKA AND THE ALASKA PENINSULA, TUE-WED, MAR 7-8.

SEVERE DROUGHT ACROSS THE CENTRAL PLAINS, THE LOWER MISSISSIPPI VALLEY, THE
TENNESSEE VALLEY, THE MID-ATLANTIC, CALIFORNIA, THE SOUTHEAST, THE SOUTHERN
APPALACHIANS, THE SOUTHERN PLAINS, AND THE SOUTHWEST.

DETAILED SUMMARY

FOR THURSDAY MARCH 02 - MONDAY MARCH 06: A SERIES OF LOW PRESSURE SYSTEMS AT
THE SURFACE AND ALOFT ARE EXPECTED TO DOMINATE MUCH OF THE NORTHERN TIER OF THE
U.S. MAR 2-5. PERIODS OF HEAVY SNOW (IN EXCESS OF 6 INCHES IN 24 HOURS) ARE
EXPECTED FOR PARTS OF THE OLYMPICS AND CASCADES (MAR 2-4) AND FOR PARTS OF THE
BITTERROOTS AND NORTHERN ROCKIES MAR 3-5. HEAVY PRECIPITATION (RAINFALL
EXCEEDING 2 INCHES IN 24 HOURS AT LOWER ELEVATIONS, SNOWFALL EXCEEDING 8 INCHES
IN 24 HOURS AT HIGHER ELEVATIONS) IS ANTICIPATED FOR PARTS OF NORTHERN
CALIFORNIA AND WESTERN OREGON MAR 4-5.



LOW PRESSURE PASSING NORTH OF MAINLAND ALASKA IS EXPECTED TO LEAD TO HIGH WINDS
(SPEEDS IN EXCESS OF 35 KNOTS) FOR PARTS OF NORTHEAST MAINLAND ALASKA MAR 2-3.
THE COMBINATION OF HIGH WINDS, AND FALLING OR BLOWING SNOW IS ANTICIPATED TO
CAUSE BLIZZARD-LIKE CONDITIONS FOR PART OF THE REGION. LOW PRESSURE NEAR THE
ALASKA PANHANDLE IS EXPECTED TO CAUSE HEAVY SNOW (AMOUNTS IN EXCESS OF 12
INCHES IN 24 HOURS) FOR PARTS OF THE SOUTHERN ALASKA PANHANDLE MAR 2-3. THE
SNOW AMOUNTS ANTICIPATED ARE MARGINAL FOR A HEAVY SNOW HAZARD, BUT THE SHAPE
WAS INCLUDED SINCE SNOWFALL IS LIKELY EVEN AT THE LOWEST ELEVATIONS. COLD HIGH
PRESSURES IS FORECAST TO LEAD TO PERIODS OF MUCH BELOW NORMAL TEMPERATURES
(NEGATIVE ANOMALIES IN EXCESS OF 20 DEGREES F) FOR PARTS OF CENTRAL AND
SOUTHERN MAINLAND ALASKA AND THE ALASKA PANHANDLE MAR 2-6.



ONSHORE FLOW IS FORECAST TO LEAD TO PRECIPITATION NEAR THE SOUTHEAST TEXAS
COAST BUT THE HEAVIEST RAINFALL IS CURRENTLY EXPECTED TO REMAIN OFFSHORE SO NO
HAZARDS ARE CURRENTLY ANTICIPATED.



LOW PRESSURE NEAR THE NORTHERN PLAINS MAR 6 MAY LEAD TO WINTRY PRECIPITATION
FOR PARTS OF THE REGION BUT LARGE MODEL SPREAD PRECLUDES THE SPECIFICATION OF A
HAZARD SHAPE AT THE CURRENT TIME.

FOR TUESDAY MARCH 07 - MONDAY MARCH 13: RIDING IS FORECAST WEST OF ALASKA WITH
TROUGHING EXPECTED OVER MAINLAND ALASKA. THIS FLOW PATTERN FAVORS MUCH BELOW
NORMAL TEMPERATURES FOR MUCH OF ALASKA. THE GEFS REFORECAST PROBABILISTIC
TEMPERATURE TOOL INDICATES A SLIGHT RISK OF MUCH BELOW NORMAL TEMPERATURES FOR
MUCH OF THE ALASKA PANHANDLE, MAINLAND ALASKA, AND THE ALEUTIANS MAR 7-13, A
MODERATE RISK OF MUCH BELOW NORMAL TEMPERATURES FOR MOST OF MAINLAND ALASKA AND
THE ALEUTIANS MAR 7-11, AND A HIGH RISK OF MUCH BELOW NORMAL TEMPERATURES FOR
PARTS OF SOUTHERN AND CENTRAL MAINLAND ALASKA AND THE ALASKA PENINSULA MAR 7-8.



ACCORDING TO THE U.S. DROUGHT MONITOR VALID ON FEBRUARY 21, SEVERE DROUGHT IS
DESIGNATED ACROSS PARTS OF CALIFORNIA, ARIZONA, THE GREAT PLAINS, ARKANSAS,
SOUTH TEXAS, AND THE EASTERN U.S. COVERAGE OF SEVERE, OR GREATER INTENSITY,
DROUGHT THROUGHOUT THE CONTINENTAL U.S. REMAINED NEARLY STEADY AT 3.31 PERCENT.
CALIFORNIA, TO THE NORTH OF POINT CONCEPTION, IS FREE OF LONG-TERM SEVERE
DROUGHT.

FORECASTER: RANDY SCHECHTER

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