Prognostic Meteorological Discussion
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FXUS21 KWNC 231819
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT APRIL 23 2014

SYNOPSIS: AT THE START OF THE HAZARDS OUTLOOK, LOW PRESSURE OVER THE GREAT
BASIN IS EXPECTED TO DEEPEN AND MOVE TO THE CENTRAL ROCKIES AND CENTRAL PLAINS
AND THEN CONTINUE EASTWARD TOWARDS THE TENNESSEE AND OHIO VALLEYS. HIGH
PRESSURE IS ANTICIPATED TO BUILD IN BEHIND THIS AREA OF LOW PRESSURE OVER THE
ROCKIES AND HIGH PLAINS. LOW PRESSURE IS FORECAST TO MOVE SOUTH OF THE
ALEUTIANS TO THE GULF OF ALASKA.

HAZARDS

HEAVY RAIN FOR PARTS OF THE NORTHERN AND CENTRAL PLAINS, SAT-SUN, APR 26-27.

HIGH WINDS FOR PARTS OF THE SOUTHWEST, SOUTHERN CALIFORNIA, GREAT BASIN,
ROCKIES, PLAINS, UPPER AND MIDDLE MISSISSIPPI VALLEYS, AND GREAT LAKES,
SAT-TUE, APR 26-29.

HEAVY SNOW FOR PARTS OF THE CENTRAL ROCKIES, SAT-SUN, APR 26-27.

HEAVY RAIN FOR PARTS OF THE SOUTHERN PLAINS, MISSISSIPPI VALLEY, GREAT LAKES,
OHIO AND TENNESSEE VALLEYS, SOUTHERN AND CENTRAL APPALACHIANS, AND SOUTHEAST
SUN-TUE, APR 27-29.

SEVERE WEATHER FOR PARTS OF THE CENTRAL AND SOUTHERN PLAINS, SAT, APR 26.

SEVERE WEATHER FOR PARTS OF THE CENTRAL AND SOUTHERN PLAINS AND LOWER AND
MIDDLE MISSISSIPPI VALLEYS, SUN, APR 27.

SEVERE WEATHER FOR PARTS OF THE SOUTHERN PLAINS, LOWER AND MIDDLE MISSISSIPPI
VALLEYS, OHIO AND TENNESSEE VALLEYS, AND SOUTHEAST, MON, APR 28.

ENHANCED WILDFIRE RISK FOR PARTS OF CENTRAL AND EASTERN NEW MEXICO,
SOUTHEASTERN COLORADO, THE WESTERN OKLAHOMA PANHANDLE, AND WESTERN TEXAS, SAT,
APR 26.

ENHANCED WILDFIRE RISK FOR PARTS OF SOUTHEASTERN NEW MEXICO AND WESTERN TEXAS,
SUN, APR 27.

FLOODING IS LIKELY, OCCURRING, OR IMMINENT FOR PARTS OF THE SOUTHEAST AND LOWER
MISSISSIPPI VALLEY, SAT-SUN, APR 26-27.

SEVERE DROUGHT FOR PARTS OF IOWA, GREAT PLAINS, SOUTHWEST, PACIFIC NORTHWEST,
GREAT BASIN, CALIFORNIA, AND HAWAII.

FLOODING POSSIBLE DUE TO ICE JAMS FOR PARTS OF THE YUKON RIVER, WED-SUN, APR
30-MAY 4.

FLOODING POSSIBLE DUE TO ICE JAMS FOR PARTS OF CENTRAL ALASKA, SUN-TUE, MAY 4-6.

DETAILED SUMMARY

FOR SATURDAY APRIL 26 - WEDNESDAY APRIL 30: THERE ARE A SIGNIFICANT NUMBER OF
FLOOD-RELATED DESIGNATIONS ON THE MAP IN THE SOUTHEAST. THESE ARE GENERALLY DUE
TO WET ANTECEDENT CONDITIONS. HEAVY RAINFALL ANTICIPATED OVER PARTS OF THIS
REGION EARLY NEXT WEEK MAY PROLONG AND EXACERBATE FLOODING CONCERNS.



THE PRIMARY CONCERN FOR HAZARDS DURING THIS PERIOD INVOLVES AN AREA OF SURFACE
AND UPPER-LEVEL LOW PRESSURE FORECAST TO DEVELOP OVER THE GREAT BASIN. THIS
SYSTEM IS EXPECTED TO DEEPEN AND MOVE TOWARDS THE ROCKIES AND PLAINS BEFORE
MOVING EASTWARD TO THE OHIO AND TENNESSE VALLEYS. EARLY IN THE PERIOD, THIS LOW
PRESSURE SYSTEM IS LIKELY TO BRING HEAVY RAIN (1 TO 1.5 INCHES) TO PARTS OF THE
NORTHERN AND CENTRAL PLAINS, AND HEAVY SNOW (6-12 INCHES) TO PARTS OF THE
CENTRAL ROCKIES. THE TIGHT PRESSURE GRADIENT BETWEEN THIS AREA OF LOW PRESSURE
AND HIGH PRESSURE BUILDING OVER THE WESTERN AND CENTRAL CONUS LEADS TO HIGH
WINDS (20-30 KTS OR GREATER) FOR PARTS OF THE SOUTHWEST, SOUTHERN CALIFORNIA,
GREAT BASIN, ROCKIES, PLAINS, UPPER AND MIDDLE MISSISSIPPI VALLEYS, AND GREAT
LAKES APR 26-APR 29. HIGH WINDS AND LOW RELATIVE HUMIDITY LEAD TO AN ENHANCED
WILDFIRE RISK FOR PARTS OF CENTRAL AND EASTERN NEW MEXICO, SOUTHEASTERN
COLORADO, THE WESTERN OKLAHOMA PANHANDLE, AND WESTERN TEXAS APR 26, AND
SOUTHEASTERN NEW MEXICO AND WESTERN TEXAS APR 27.



AS THE AREA OF LOW PRESSURE MOVES ACROSS THE PLAINS, WARM MOIST AIR IS EXPECTED
TO BE DRAWN NORTHWARD FROM THE GULF OF MEXICO. THIS WILL INCREASE INSTABILITY
ACROSS THE REGION AND SEVERE WEATHER IS ANTICIPATED FOR PARTS OF THE CENTRAL
AND SOUTHERN PLAINS APR 26, FOR PARTS OF THE CENTRAL AND SOUTHERN PLAINS AND
LOWER AND MIDDLE MISSISSIPPI VALLEYS APR 27, AND FOR PARTS OF THE SOUTHERN
PLAINS, LOWER AND MIDDLE MISSISSIPPI VALLEYS, OHIO AND TENNESSEE VALLEYS, AND
SOUTHEAST APR 28. IN ADDITION, HEAVY RAIN (1-4 INCHES) IS EXPECTED FOR PARTS OF
THE SOUTHERN PLAINS, MISSISSIPPI VALLEY, GREAT LAKES, OHIO AND TENNESSEE
VALLEYS, SOUTHERN AND CENTRAL APPALACHIANS, AND SOUTHEAST APR 27-29.



FLOODING IS POSSIBLE DUE TO ICE JAMS FOR PARTS OF THE YUKON RIVER WED APR 30.

FOR THURSDAY MAY 01 - WEDNESDAY MAY 07: BY WEEK-2, THE GENERAL CIRCULATION
PATTERN AT 500-HPA IS EXPECTED TO FEATURE TROUGHS OVER THE EASTERN AND WESTERN
U.S. AND THE ALEUTIANS, WHILE RIDGES ARE ANTICIPATED OVER THE WEST-CENTRAL
CONUS AND ALASKA. NO SPECIFIC HAZARDS CAN BE DESIGNATED OVER THE CONUS WITH
CONFIDENCE AT THIS RANGE, OTHER THAN CONTINUING LONG-TERM DROUGHT AREAS.



ACCORDING TO THE U.S. DROUGHT MONITOR VALID ON APRIL 15, SEVERE DROUGHT
COVERAGE HAS INCREASED NEARLY A PERCENTAGE POINT, FROM 24.23 PERCENT LAST WEEK
(CONUS) TO 25.20 PERCENT THIS WEEK.



FLOODING IS POSSIBLE FOR PORTIONS OF THE YUKON RIVER AND PARTS OF CENTRAL
ALASKA DUE TO ICE JAMS AS RIVER ICE BREAK-UP IS EXPECTED TO OCCUR DURING THE
PERIOD.

FORECASTER: RANDY SCHECHTER

$$




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