Prognostic Meteorological Discussion
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FXUS21 KWNC 181821
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT APRIL 18 2014

SYNOPSIS: AT THE START OF THE HAZARDS OUTLOOK, SEVERAL WEAK WEATHER
DISTURBANCES ARE FORECAST TO MOVE ACROSS THE CONTIGUOUS U.S. BY THE MIDDLE OF
NEXT WEEK, A MORE SIGNIFICANT STORM SYSTEM IS PREDICTED TO DEVELOP OVER THE
CENTRAL PORTION OF THE COUNTRY. SEVERAL NORTHERN PACIFIC STORM SYSTEMS ARE
ANTICIPATED TO INFLUENCE THE SOUTHERN COASTAL AREAS OF ALASKA.

HAZARDS

HEAVY RAIN ACROSS PARTS OF THE NORTHERN PLAINS AND NORTH-CENTRAL MISSISSIPPI
VALLEY, WED-THU, APR 23-24.

FLOODING IS OCCURRING, IMMINENT, OR LIKELY FOR THE CENTRAL GULF COAST STATES
AND NORTHERN PARTS OF FLORIDA, LOWER MICHIGAN, PARTS OF NEW YORK AND NEW
ENGLAND, AND OVER NORTHEASTERN NORTH DAKOTA AND ADJACENT NORTHWESTERN MINNESOTA
(THE RED RIVER OF THE NORTH), MON-TUE, APR 21-22.

HIGH WINDS ARE PREDICTED FOR MUCH OF NEVADA, SOUTHWEST UTAH, ARIZONA AND NEW
MEXICO, TUE-WED, APR 22-23.

ENHANCED WILDFIRE RISK FOR PARTS OF THE SOUTHWEST, TUE-WED, APR 22-23.

HIGH WINDS FOR PARTS OF THE NORTHERN AND CENTRAL PLAINS, WED, APR 23.

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

DETAILED SUMMARY

FOR MONDAY APRIL 21 - FRIDAY APRIL 25: THERE ARE A SIGNIFICANT NUMBER OF
FLOOD-RELATED DESIGNATIONS ON THE MAP IN THE EAST. THESE ARE GENERALLY DUE TO
WET ANTECEDENT CONDITIONS, ANTICIPATED RAINFALL DURING (OR IN THE TWO DAYS
PRIOR TO) THIS PERIOD, OR SNOW MELT (IN NORTHERN AREAS).



BY THE MIDDLE OF NEXT WEEK, A SIGNIFICANT 500-HPA TROUGH IS PREDICTED BY MOST
MODELS TO MOVE ACROSS THE WESTERN CONUS. HIGH WINDS (20-30 KTS OR MORE) ARE
FORECAST FOR NEVADA, SOUTHWEST UTAH, ARIZONA AND NEW MEXICO, IN CONNECTION WITH
THIS TROUGH. ADDITIONALLY, HIGH WINDS COMBINED WITH DRY FUEL AND LOW RELATIVE
HUMIDITY WILL INCREASE CHANCES FOR CRITICAL FIRE WEATHER. AS THIS PREDICTED
TROUGH MOVES OUT INTO THE PLAINS, THERE IS ALSO THE POTENTIAL FOR STRONG TO
SEVERE THUNDERSTORMS TO DEVELOP. HOWEVER, THE LATEST GUIDANCE SUGGESTS THAT ANY
STORMS THAT DO FORM COULD BE LIMITED BY THE AMOUNT OF UNSTABLE, LOW-LEVEL GULF
MOISTURE AVAILABLE TO THEM. THAT SAID, SHEAR PARAMETERS COULD BE IMPRESSIVE, SO
THIS SITUATION NEEDS TO BE CAREFULLY MONITORED. HIGH WINDS IN EXCESS OF 30
KNOTS ARE EXPECTED AHEAD OF THE SURFACE LOW ACROSS THE CENTRAL AND NORTHERN
PLAINS ON WEDNESDAY.



ABOVE-NORMAL TEMPERATURES ARE EXPECTED AHEAD OF THAT SYSTEM AS WELL ACROSS THE
SOUTH-CENTRAL CONUS, THOUGH DAYTIME HIGHS PEAKING IN THE 80S TO NEAR 90 HARDLY
SEEMS HAZARDOUS GIVEN THE TIME OF YEAR.



IN THE NORTHWEST, RAINFALL TOTALING 0.75-1.5 INCHES IS POSSIBLE LATER IN THIS
PERIOD, THOUGH THIS TOO IS NOT CONSIDERED HAZARDOUS.



SEVERAL LOW PRESSURE SYSTEMS ARE FORECAST TO MOVE ACROSS THE ALEUTIANS AND GULF
OF ALASKA, BRINGING PRECIPITATION TO MUCH OF THE SOUTHERN ALASKA COAST,
ESPECIALLY THE PANHANDLE. AT THIS TIME, NO HAZARDS ARE DEPICTED FOR THE STATE.

FOR SATURDAY APRIL 26 - FRIDAY MAY 02: BY WEEK-2, THE GENERAL CIRCULATION
PATTERN AT 500-HPA IS EXPECTED TO FEATURE A FAST, WESTERLY JET ACROSS THE
NORTHERN PACIFIC, WHICH WILL DIRECT ABUNDANT MOISTURE INTO THE WEST COAST.
ANOMALOUSLY WET CONDITIONS COULD EXTEND FAIRLY FAR SOUTH IN CALIFORNIA AND
POINTS EAST. A RIDGE IS FORECAST TO EXTEND FROM THE WEST-CENTRAL CONUS
NORTHWARD TO NORTHWESTERN NORTH AMERICA. NO SPECIFIC HAZARDS CAN BE DESIGNATED
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.

FORECASTER: STEPHEN BAXTER

$$




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