Prognostic Meteorological Discussion
Issued by NWS

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2
000
FXUS21 KWNC 272050
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EST FEBRUARY 27 2015

SYNOPSIS: AN ARCTIC AIR MASS IS FORECAST TO MOVE SOUTHWARD AND EASTWARD OUT OF
WESTERN CANADA EARLY IN THE PERIOD. UNSEASONABLY COLD AIR IS EXPECTED TO
OVERSPREAD MOST OF THE LOWER 48 STATES, REACHING THE EASTERN SEABOARD BY THE
END OF NEXT WEEK. SEVERAL PRECIPITATION EVENTS ARE PREDICTED ACROSS MUCH OF THE
CENTRAL AND EASTERN LOWER 48 STATES DURING THE FIRST HALF OF THE OUTLOOK
PERIOD, WITH A RANGE OF PRECIPITATION TYPES EXPECTED. IN THE HIGHER ELEVATIONS
OF THE SOUTHWEST, AN EXTENDED PERIOD OF SNOWY CONDITIONS IS ANTICIPATED.
RELATIVELY MILD AND WET CONDITIONS ARE PREDICTED FOR A LARGE PORTION OF ALASKA,
AS A SERIES OF PACIFIC STORM SYSTEMS MOVES ACROSS THE STATE. IN HAWAII, AN
UPPER-AIR DISTURBANCE IS FORECAST TO BRING HEAVY PRECIPITATION, ESPECIALLY FOR
THE SOUTHERN ISLANDS OF THE ARCHIPELAGO.

HAZARDS

MUCH BELOW-NORMAL TEMPERATURES FOR MOST OF THE CONTIGUOUS U.S., TUE-FRI, MAR
3-6.

PERIODS OF HEAVY SNOW IN THE FOUR CORNERS REGION, MON-WED, MAR 2-4.

PERIODS OF HEAVY PRECIPITATION (SNOW, SLEET, AND FREEZING RAIN) FROM THE
NORTH-CENTRAL MISSISSIPPI VALLEY EASTWARD ACROSS THE GREAT LAKES REGION,
NORTHERN OHIO VALLEY, AND NORTHEAST, MON-THU, MAR 2-5.

PERIODS OF HEAVY RAIN FOR THE CENTRAL AND SOUTHERN MISSISSIPPI VALLEY, THE
SOUTHERN GREAT LAKES REGION, THE OHIO AND TENNESSEE VALLEYS, MUCH OF THE
INTERIOR SOUTHEAST, MOST OF THE APPALACHIANS, AND FROM VIRGINIA TO SOUTHERN
MAINE, MON-THU, MAR 2-5.

PERIODS OF HEAVY RAIN FOR HAWAII (ESPECIALLY MAUI AND THE BIG ISLAND), MON-SAT,
MAR 2-7.

FLOODING IS OCCURRING OR IMMINENT IN CENTRAL MISSISSIPPI, MON-TUE, MAR 2-3.

A SLIGHT RISK OF MUCH BELOW-NORMAL MINIMUM TEMPERATURES FOR THE SOUTHERN
PLAINS, MISSISSIPPI VALLEY, GREAT LAKES REGION, NORTHEAST, MID-ATLANTIC, OHIO
AND TENNESSEE VALLEYS, AND THE CENTRAL GULF COAST STATES, SAT-MON, MAR 7-9.

A MODERATE RISK OF MUCH BELOW-NORMAL MINIMUM TEMPERATURES FOR MUCH OF THE
SOUTHERN PLAINS, MISSISSIPPI VALLEY, THE GREAT LAKES REGION, THE OHIO VALLEY
AND LOWER TENNESSEE VALLEY, AND FROM NORTHERN WEST VIRGINIA AND NORTHERN
MARYLAND NORTHEASTWARD TO MAINE, SAT-MON, MAR 7-9.

SEVERE DROUGHT FOR THE CENTRAL AND SOUTHERN GREAT PLAINS, SOUTHWEST, GREAT
BASIN, CALIFORNIA, THE PACIFIC NORTHWEST, AND TENNESSEE VALLEY.

DETAILED SUMMARY

FOR MONDAY MARCH 02 - FRIDAY MARCH 06: AN ARCTIC AIR MASS IS FORECAST TO MOVE
SOUTHWARD AND EASTWARD OUT OF WESTERN CANADA EARLY IN THE PERIOD. UNSEASONABLY
COLD AIR IS EXPECTED TO OVERSPREAD MOST OF THE LOWER 48 STATES, REACHING THE
EASTERN SEABOARD BY THE END OF NEXT WEEK. TEMPERATURES ARE PREDICTED TO RANGE
BETWEEN 12 AND 32 DEGREES F BELOW NORMAL, WITH THE LARGEST DEPARTURES IN THE
CENTRAL CONUS.



AS THIS ARCTIC AIR MASS MOVES ACROSS THE NORTHERN GREAT PLAINS ON TUESDAY, IT
IS EXPECTED TO BE ACCOMPANIED BY GUSTY WINDS OF 20-25 KNOTS, WHICH DOESN`T
QUITE REACH THE HAZARDOUS WIND SPEED CRITERION (30 KNOTS). THEREFORE, NO WIND
HAZARD HAS BEEN PLACED ON THE MAP IN THIS REGION.



PERIODS OF HEAVY SNOW ARE PREDICTED FOR THE FOUR CORNERS REGION FROM MAR 2-4,
AS A SURFACE LOW PRESSURE SYSTEM TRAVERSES THE AREA AND INTERACTS WITH ARCTIC
AIR. A POSITIVELY TILTED 500-HPA TROUGH, EXPECTED TO BE JUST WEST OF THIS
REGION, WILL HELP PROVIDE A FAVORABLE ENVIRONMENT FOR PRECIPITATION WITH ITS
ASSOCIATED LARGE-SCALE ASCENT OF AIR.



SOUTHERLY FLOW IS PREDICTED TO BRIEFLY DEVELOP ACROSS THE SOUTHEASTERN QUARTER
OF THE CONUS, PRIOR TO THE NEXT SOUTHWARD PUSH OF ARCTIC AIR. CURRENT THINKING
IS THAT THE BOUNDARY SEPARATING THE WARM, MOIST AIR FROM THE COLD, DRY AIR
(INITIALLY STRETCHING FROM THE CENTRAL PLAINS TO THE CAROLINAS) WILL ADVANCE
AND RETREAT SEVERAL TIMES DURING THIS PERIOD. RATHER THAN HAVE A SINGLE, MAJOR
STORM SYSTEM TO CONTEND WITH, IT APPEARS THE ASSOCIATED PRECIPITATION WILL BE
DISTRIBUTED AMONG TWO, WEAKER STORM SYSTEMS, WHICH GENERALLY TRACK FROM THE
CENTRAL PLAINS NORTHEASTWARD TOWARDS THE GREAT LAKES REGION. THIS COMPLEX AND
VERY DYNAMIC SETUP MAKES IT EXTREMELY DIFFICULT TO ACCURATELY DETERMINE WHERE
THE SWATHS OF RAIN, SNOW, FREEZING RAIN, AND SLEET WILL BE, AND HOW THEY WILL
SHIFT WITH TIME. AT THIS TIME, THE AREA MOST LIKELY TO RECEIVE HEAVY WINTER
PRECIPITATION (SNOW, SLEET, FREEZING RAIN) IS FROM THE NORTH-CENTRAL
MISSISSIPPI VALLEY EASTWARD ACROSS THE GREAT LAKES REGION, NORTHERN OHIO
VALLEY, AND NORTHEAST, MON-THU, MAR 2-5. THE AREA MOST LIKELY TO RECEIVE HEAVY
RAINFALL IS THE CENTRAL AND SOUTHERN MISSISSIPPI VALLEY, THE SOUTHERN GREAT
LAKES REGION, THE OHIO AND TENNESSEE VALLEYS, MUCH OF THE INTERIOR SOUTHEAST,
MOST OF THE APPALACHIANS, AND FROM VIRGINIA TO SOUTHERN MAINE, MON-THU, MAR
2-5. THERE IS A FAIRLY LARGE AREA OF OVERLAP BETWEEN THESE TWO SHAPES. THIS
OVERLAP AREA DEPICTS SEVERAL THINGS. FIRST, THIS IS THE FORECASTED AREA MOST
LIKELY TO RECEIVE FREEZING RAIN AND SLEET. SECOND, THIS AREA ALSO DEPICTS A
TRANSITION ZONE WHERE THE PRECIPITATION TYPES ARE EXPECTED TO CHANGE SEVERAL
TIMES DURING THIS PERIOD.



ANOTHER CONSIDERATION ASSOCIATED WITH THE ANTICIPATED PRECIPITATION EVENTS OVER
THE CENTRAL AND EASTERN CONUS IS SEVERE WEATHER. WITH SO MUCH UNCERTAINTY AS TO
WHETHER ARCTIC AIR OR MARITIME TROPICAL AIR DOMINATES THE SOUTHERN PLAINS, THE
LOWER MISSISSIPPI VALLEY, AND THE OHIO AND TENNESSEE VALLEYS, NO AREA OF SEVERE
WEATHER IS CURRENTLY INDICATED ON THE MAP. IF WARM ADVECTION OF MOIST, UNSTABLE
GULF AIR DOMINATES, THE CHANCES FOR SEVERE WEATHER WILL INCREASE IN THIS AREA.
HOWEVER, IF COLD, DRY ARCTIC AIR DOMINATES, THE BOUNDARY LAYER WILL BE VERY
STABLE, WITH WINDS BLOWING OFFSHORE, EFFECTIVELY SHUTTING DOWN THE POTENTIAL
FOR SEVERE THUNDERSTORM ACTIVITY.



FLOODING IS EITHER IMMINENT OR OCCURRING IN CENTRAL MISSISSIPPI FROM MONDAY TO
TUESDAY, ESPECIALLY IN REGARDS TO THE BIG BLACK RIVER AT BENTONIA AND WEST.
SEVERAL HYDROGRAPHS (U.S. ARMY CORPS OF ENGINEERS) INDICATE THIS RIVER WILL
REMAIN ABOVE FLOOD STAGE AT LEAST INTO TUESDAY. ACCORDING TO THE ADVANCED
HYDROLOGIC PREDICTION SYSTEM (AHPS), 3-5 INCHES OF RAIN HAS FALLEN IN THIS AREA
DURING THE PAST 7-DAYS.



A 500-HPA TROUGH OVER THE EAST-CENTRAL PACIFIC IS PREDICTED TO SHIFT WEST OF
HAWAII, BEFORE RESUMING ITS EASTWARD MOTION. AS A RESULT, SEVERAL MODELS
PREDICT RAINFALL AMOUNTS OF 2-5 INCHES FOR THE ISLANDS IN GENERAL, AND LOCALLY
UP TO A FOOT OF RAIN IS POSSIBLE IN MAUI AND THE BIG ISLAND DURING THIS PERIOD.



IN ALASKA, RELATIVELY FAST ZONAL FLOW IS FORECAST DURING THIS PERIOD, WHICH
REDUCES THE POSSIBILITY OF EXTREMES FOR BOTH TEMPERATURE AND PRECIPITATION.
NEAR TO ABOVE-NORMAL TEMPERATURES, AND ABOVE-MEDIAN PRECIPITATION, ARE
ANTICIPATED FOR ALASKA DURING THIS PERIOD.

FOR SATURDAY MARCH 07 - FRIDAY MARCH 13: THERE IS A SLIGHT RISK OF MUCH
BELOW-NORMAL TEMPERATURES FOR THE SOUTHERN PLAINS, MISSISSIPPI VALLEY, GREAT
LAKES REGION, NORTHEAST, MID-ATLANTIC, OHIO AND TENNESSEE VALLEYS, AND THE
CENTRAL GULF COAST STATES, SAT-MON, MAR 7-9. A MODERATE RISK OF MUCH
BELOW-NORMAL MINIMUM TEMPERATURES IS INDICATED FOR MUCH OF THE SOUTHERN PLAINS,
MISSISSIPPI VALLEY, THE GREAT LAKES REGION, THE OHIO VALLEY AND LOWER TENNESSEE
VALLEY, AND FROM NORTHERN WEST VIRGINIA AND NORTHERN MARYLAND NORTHEASTWARD TO
MAINE, SAT-MON, MAR 7-9.



THE MOST RECENT U.S. DROUGHT MONITOR, RELEASED FEBRUARY 26, 2015, INDICATES A
SLIGHT DECREASE IN THE AREAL COVERAGE OF SEVERE TO EXCEPTIONAL DROUGHT (D2 TO
D4) IN THE PAST WEEK FROM 16.44 TO 16.42 PERCENT ACROSS THE CONTINENTAL U.S.
FORTY PERCENT OF CALIFORNIA REMAINS DESIGNATED IN THE EXCEPTIONAL DROUGHT (D4)
CATEGORY. ALTHOUGH MOST REVISIONS MADE TO THE MONITOR THIS WEEK ARE FAIRLY
SMALL, THE MORE NOTABLE CHANGES INCLUDE A GENERAL 1-CATEGORY IMPROVEMENT IN
KENTUCKY AND WESTERN TENNESSEE, AND A 1-CATEGORY DEGRADATION ACROSS THE CENTRAL
GULF COAST AREA.

FORECASTER: ANTHONY ARTUSA

$$




USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.