Prognostic Meteorological Discussion
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FXUS21 KWNC 042020
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EST MARCH 04 2015

SYNOPSIS: ARCTIC HIGH PRESSURE IS EXPECTED OVER THE SOUTH-CENTRAL AND EASTERN
U.S. SURFACE LOW PRESSURE IS EXPECTED TO MOVE NORTHEASTWARD ACROSS THE GREAT
LAKES AND NORTH OF NEW ENGLAND. RETURN FLOW AROUND THE REAR SIDE OF THE AREA OF
HIGH PRESSURE WILL GRADUALLY DRAW MOISTURE NORTHWARD FROM THE GULF OF MEXICO.
SURFACE LOW PRESSURE IS FORECAST TO CROSS CENTRAL ALASKA WITH COLD SURFACE HIGH
PRESSURE THEN ANTICIPATED TO BUILD OVER WESTERN AND NORTHERN ALASKA. A 2ND AREA
OF SURFACE LOW PRESSURE IS EXPECTED TO APPROACH THE ALEUTIANS. DEEP UPPER-LEVEL
LOW PRESSURE IS FORECAST NEAR AND NORTH OF THE HAWAIIAN ISLANDS. DURING WEEK 2,
AREAS OF UPPER-LEVEL LOW PRESSURE ARE FORECAST OVER THE NORTHEAST, SOUTHERN
PLAINS, AND ALASKA.

HAZARDS

HEAVY RAIN FOR PARTS OF THE TEXAS AND LOUISIANA GULF COAST, MON-TUE, MAR 9-10.

HIGH WINDS FOR COASTAL SECTIONS OF THE NORTHEAST AND NORTHERN MID-ATLANTIC,
SAT, MAR 7.

MUCH BELOW NORMAL TEMPERATURES FOR MUCH OF THE SOUTH-CENTRAL AND EASTERN CONUS
(EXCEPT THE SOUTHEAST), SAT-SUN, MAR 7-8.

HEAVY SNOW FOR PARTS OF CENTRAL ALASKA NEAR AND SOUTH OF THE BROOKS RANGE, SAT,
MAR 7.

PERIODS OF HIGH WINDS FOR PARTS OF WESTERN AND SOUTHERN COASTAL ALASKA,
SAT-WED, MAR 7-11.

SIGNIFICANT WAVES FOR COASTAL SECTIONS OF SOUTHWESTERN ALASKA, SAT, MAR 7.

SIGNIFICANT WAVES FOR PARTS OF THE ALEUTIANS, MON-TUE, MAR 9-10.

MUCH BELOW NORMAL TEMPERATURES FOR PARTS OF CENTRAL AND EASTERN ALASKA,
MON-WED, MAR 9-11.

FLOODING POSSIBLE OR LIKELY FOR PARTS OF KENTUCKY.

A SLIGHT RISK OF MUCH BELOW-NORMAL MINIMUM TEMPERATURES FOR MUCH OF THE PLAINS,
PARTS OF THE NORTHERN ROCKIES, GREAT LAKES, MISSISSIPPI AND TENNESSEE VALLEYS,
AND SOUTHEAST, THU-MON, MAR 12-16.

A SLIGHT RISK OF MUCH BELOW NORMAL MINIMUM TEMPERATURES FOR PARTS OF THE
MID-ATLANTIC AND NORTHEAST, FRI-SUN, MAR 13-15.

A SLIGHT RISK OF MUCH BELOW NORMAL MINIMUM TEMPERATURES FOR MUCH OF CENTRAL AND
EASTERN ALASKA, THU-SAT, MAR 12-14.

A MODERATE RISK OF MUCH BELOW NORMAL MINIMUM TEMPERATURES FOR PARTS OF CENTRAL
EASTERN ALASKA, THU, MAR 12.

PERIODS OF HEAVY RAIN FOR HAWAII (ESPECIALLY MAUI AND THE BIG ISLAND), SAT-TUE,
MAR 7-11.

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

DETAILED SUMMARY

FOR SATURDAY MARCH 07 - WEDNESDAY MARCH 11: ARCTIC HIGH PRESSURE DOMINATES MUCH
OF THE EASTERN AND SOUTH-CENTRAL CONUS WHICH LEADS TO MUCH BELOW NORMAL
TEMPERATURES (NEGATIVE ANOMALIES OF 12-24 DEGREES) SPREADING EASTWARD ACROSS
MUCH OF THE SOUTH-CENTRAL AND EASTERN CONUS (EXCEPT THE SOUTHEAST) MAR 7-8. LOW
PRESSURE IS FORECAST TO MOVE ACROSS THE NORTHERN GREAT LAKES AND NORTH OF NEW
ENGLAND. THE TIGHT PRESSURE GRADIENT BETWEEN THIS AREA OF LOW PRESSURE AND THE
AREA OF ARCTIC HIGH PRESSURE LEADS TO HIGH WINDS (IN EXCESS OF 30 KNOTS) FOR
COASTAL SECTIONS OF THE NORTHEAST AND NORTHERN MID-ATLANTIC MAR 7. AS THE
ARCTIC HIGH PRESSURE MOVES OFF THE EAST COAST, A MOIST RETURN FLOW IS EXPECTED
TO GET ESTABLISHED LEADING TO HEAVY RAIN FOR PARTS OF THE TEXAS AND LOUISIANA
GULF COAST MAR 9-10. THIS RAINFALL IS EXPECTED TO GRADUALLY SPREAD NORTH AND
EASTWARD, BUT MODEL UNCERTAINTY PRECLUDES THE SPECIFICATION OF ADDITIONAL
HAZARD SHAPES AT THIS TIME.



ANTECEDENT RAINFALL, ALONG WITH SNOW MELT AND THE EXPECTATION OF ADDITIONAL
PRECIPITATION BEFORE THE START OF THE PERIOD LEADS TO POSSIBLE OR LIKELY RIVER
FLOODING FOR PARTS OF KENTUCKY.



LOW PRESSURE AND ITS ASSOCIATED FRONTAL SYSTEM ARE EXPECTED TO MOVE ACROSS
CENTRAL AND SOUTHERN ALASKA LEADING TO HEAVY SNOW (IN EXCESS OF 6 INCHES IN 24
HOURS) FOR PARTS OF CENTRAL ALASKA NEAR AND SOUTH OF THE BROOKS RANGE MAR 7.
HIGH WINDS (IN EXCESS OF 30 KNOTS) ARE ANTICIPATED FOR PARTS OF WESTERN AND
SOUTHERN COASTAL ALASKA MAR 7-11 AS A 2ND AREA OF LOW PRESSURE APPROACHES THE
ALEUTIANS. IN ADDITION, SIGNIFICANT WAVES (IN EXCESS OF 18 FEET) ARE
ANTICIPATED FOR COASTAL SECTIONS OF SOUTHWESTERN ALASKA MAR 7, AND THE
ALEUTIANS MAR 9-10. HIGH PRESSURE BUILDING OVER WESTERN AND NORTHERN ALASKA
LEADS TO MUCH BELOW NORMAL TEMPERATURES (20-30 DEGREE NEGATIVE ANOMALIES) FOR
PARTS OF CENTRAL AND EASTERN ALASKA MAR 9-11.



A 500-HPA TROUGH OVER THE EAST-CENTRAL PACIFIC IS PREDICTED NEAR AND NORTH OF
HAWAII. 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.

FOR THURSDAY MARCH 12 - WEDNESDAY MARCH 18: THERE IS A SLIGHT RISK OF MUCH
BELOW-NORMAL TEMPERATURES FOR MUCH OF THE PLAINS, PARTS OF THE NORTHERN
ROCKIES, GREAT LAKES, MISSISSIPPI AND TENNESSEE VALLEYS, AND THE SOUTHEAST
DURING MAR 12-16 DUE TO AN AREA OF UPPER-LEVEL LOW PRESSURE. THE EXPECTATION OF
UPPER-LEVEL LOW PRESSURE ALSO LEADS TO A SLIGHT RISK OF MUCH BELOW-NORMAL
TEMPERATURES FOR PARTS OF THE MID-ATLANTIC AND NORTHEAST MAR 13-15.



UPPER-LEVEL LOW PRESSURE LEADS TO A SLIGHT RISK OF MUCH BELOW NORMAL
TEMPERATURES FOR MUCH OF CENTRAL AND EASTERN ALASKA MAR 12-14, AND A MODERATE
RISK OF MUCH BELOW NORMAL TEMPERATURES FOR PARTS OF EAST-CENTRAL ALASKA MAR 12.



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: RANDY SCHECHTER

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