Prognostic Meteorological Discussion
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FXUS21 KWNC 151850
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT APRIL 15 2014

SYNOPSIS: AT THE START OF THE HAZARDS OUTLOOK, FRONTAL SYSTEMS ARE FORECAST
OVER THE PACIFIC NORTHWEST, THE MISSISSIPPI VALLEY, AND JUST OFF THE SOUTHERN
ATLANTIC COAST. SEVERAL DAYS LATER, HIGH PRESSURE IS PREDICTED TO OVERSPREAD
THE EASTERN STATES, WHILE ANOTHER FRONTAL SYSTEM MOVES INTO THE NORTHWEST.
SEVERAL NORTHERN PACIFIC STORM SYSTEMS ARE ANTICIPATED TO INFLUENCE THE
SOUTHERN COASTAL AREAS OF ALASKA.

HAZARDS

HEAVY RAIN OVER THE SOUTHERN ATLANTIC COAST STATES, FRI-SAT, APR 18-19.

FLOODING IS OCCURRING OR IMMINENT OVER THE CENTRAL GULF COAST STATES, THE LOWER
OHIO VALLEY, AND OVER NORTHEASTERN NORTH DAKOTA AND ADJACENT NORTHWESTERN
MINNESOTA (THE RED RIVER OF THE NORTH), FRI-SAT, APR 18-19.

FLOODING IS LIKELY OVER LOWER MICHIGAN, AND THE MIDWEST, FRI-SAT, APR 18-19.

FLOODING IS POSSIBLE OVER PORTIONS OF NEW YORK AND NEW ENGLAND, FRI-SAT, APR
18-19.

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

DETAILED SUMMARY

FOR FRIDAY APRIL 18 - TUESDAY APRIL 22: PERIODS OF HEAVY RAIN (2-4 INCHES) ARE
PREDICTED FOR NORTHERN AND CENTRAL FLORIDA, AND THE COASTAL AREAS OF GEORGIA
AND SOUTH CAROLINA EARLY IN THE PERIOD, IN ASSOCIATION WITH AN OFFSHORE FRONT.
NORTH OF THIS REGION, THE FRONT AND ITS ASSOCIATED PRECIPITATION ARE EXPECTED
TO REMAIN LARGELY OFFSHORE.



THERE ARE A SIGNIFICANT NUMBER OF FLOOD-RELATED DESIGNATIONS ON THE MAP IN THE
EAST. THESE ARE GENERALLY DUE TO WET ANTECEDENT CONDITIONS, PREDICTED RAINFALL
DURING (OR IN THE TWO DAYS PRIOR TO) THIS PERIOD, OR (IN THE GREAT LAKES/UPPER
MIDWEST REGION) SNOW MELT. UP TO NOW, COLDER WEATHER HAS PREVENTED RAPID SNOW
MELT, WHICH WOULD OTHERWISE RESULT IN SIGNIFICANT FLOODING. HOWEVER, THIS IS
OFFSET SOMEWHAT BY FROST DEPTHS OF 3.5 - 5.0 FEET IN PARTS OF THE UPPER
MIDWEST, WHICH PREVENTS MELT WATER FROM PERCOLATING DEEP INTO THE SOIL, AND
RESULTS IN INCREASED RUNOFF. FOR MORE INFORMATION, PLEASE REFER TO THE NORTH
CENTRAL RIVER FORECAST CENTER SITE:
HTTP://WWW.CRH.NOAA.GOV/NCRFC/CONTENT/SOILTEMP/SOILTEMP_GD.PHP?PE=OB&DEPTH=02



FOR PARTS OF THE SOUTHERN AND CENTRAL HIGH PLAINS, TEMPERATURES FRIDAY MORNING
ARE EXPECTED TO BE NEAR FREEZING, WHICH WOULD FURTHER STRESS THE WINTER WHEAT
CROP IN THIS REGION (ESPECIALLY KANSAS). THIS COMES ON THE HEELS OF HARD
FREEZES THE PAST TWO MORNINGS.



IN THE SOUTHWEST, THERE IS THE POSSIBILITY FOR ENHANCED WILDFIRE CONDITIONS
LATE IN THIS PERIOD, ESPECIALLY IN ARIZONA, AS A 500-HPA TROUGH APPROACHES THE
AREA. THERE IS NOT YET ENOUGH CONFIDENCE TO JUSTIFY THE DESIGNATION OF A
WILDFIRE AREA ON THE MAP, BUT THE SITUATION WILL BE MONITORED OVER THE NEXT FEW
DAYS.



AN UPPER-LEVEL TROUGH IS FORECAST TO DIG SOUTHWARD OVER THE ALEUTIANS, WITH LOW
PRESSURE AT THE SURFACE TRACKING NORTHWARD OUT AHEAD OF IT, BRINGING SEVERAL
INCHES OF PRECIPITATION TO SOUTH-CENTRAL AND SOUTHEASTERN ALASKA, INCLUDING THE
PANHANDLE. AT THIS TIME, NO HAZARDS ARE ANTICIPATED WITH THIS SYSTEM.

FOR WEDNESDAY APRIL 23 - TUESDAY APRIL 29: BY WEEK-2, THERE IS SIGNIFICANT
MODEL UNCERTAINTY IN THE PREDICTED 500-HPA CIRCULATION PATTERN ACROSS THE NORTH
AMERICA DOMAIN, WHICH IS OFTEN THE CASE DURING A TRANSITIONAL SEASON SUCH AS
SPRING. THIS IS TYPICALLY ASSOCIATED WITH SHORTER-WAVELENGTH WEATHER FEATURES,
WHICH ARE NOTORIOUSLY DIFFICULT TO TIME ACCURATELY, AS WELL AS OCCASIONAL SPLIT
FLOW REGIMES. AS A RESULT, THE ONLY HAZARDS ANTICIPATED WITH CONFIDENCE ARE THE
LONG-TERM DROUGHT AREAS.



ACCORDING TO THE U.S. DROUGHT MONITOR VALID ON APRIL 8, SEVERE DROUGHT COVERS
24.2 PERCENT OF THE CONUS, WHICH IS A MINOR INCREASE SINCE THE PREVIOUS WEEK
AND THE LARGEST COVERAGE SINCE SEPTEMBER 2013.

FORECASTER: ANTHONY ARTUSA

$$




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