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000
FXUS21 KWNC 211857
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT MAY 21 2013

SYNOPSIS: AT THE START OF THE PERIOD, A COLD FRONT IS PREDICTED TO MOVE OFF THE
ATLANTIC AND GULF COASTS, WITH THE WESTERN PORTION OF THIS FRONT EXTENDING
NORTHWESTWARD ACROSS TEXAS AND EASTERN COLORADO. HIGH PRESSURE IS FORECAST TO
BUILD IN BEHIND THIS COLD FRONT ACROSS THE EASTERN HALF OF THE CONTIGUOUS
UNITED STATES. THE WESTERN PORTION OF THE COLD FRONT IN TEXAS AND EASTERN
COLORADO IS ANTICIPATED TO BECOME STATIONARY AND TRANSFORM INTO A WARM FRONT,
WHICH IS FORECAST TO MIGRATE NORTHWARD ACROSS THE CENTRAL STATES. IN ALASKA, A
LOW PRESSURE SYSTEM OVER THE FAR NORTHERN PACIFIC IS EXPECTED TO TRACK
NORTHWARD TO THE CENTRAL ALEUTIANS, WITH MUCH OF ITS ENERGY BEING DIRECTED
EASTWARD INTO THE NORTHERN GULF OF ALASKA.

HAZARDS

HEAVY RAIN FOR IOWA AND SMALL PORTIONS OF NEARBY NEBRASKA AND MISSOURI,
FRI-SAT, MAY 24-25.

HEAVY RAIN FOR SOUTHERN IOWA, WESTERN ILLINOIS AND EXTREME NORTHEASTERN
MISSOURI, SUN-MON, MAY 26-27.

HIGH WINDS ALONG THE CENTRAL AND SOUTHERN CALIFORNIA COAST, FRI, MAY 24.

HIGH WINDS OVER THE NORTHERN HIGH PLAINS, FRI, MAY 24.

MUCH ABOVE NORMAL TEMPERATURES FOR THE ALASKA PANHANDLE AND SOUTHEASTERN
PORTIONS OF THE MAINLAND, FRI-SUN, MAY 24-26.

RIVER FLOODING OCCURRING OR IMMINENT IN FAR NORTHERN PARTS OF NORTH DAKOTA, AND
THE MIDDLE/LOWER MISSISSIPPI VALLEY, FRI-SAT, MAY 24-25.

RIVER FLOODING LIKELY IN NORTH-CENTRAL PARTS OF NORTH DAKOTA AND PARTS OF THE
MIDDLE MISSISSIPPI VALLEY, FRI-SAT, MAY 24-25.

RIVER FLOODING POSSIBLE FOR PORTIONS OF NORTH DAKOTA, MINNESOTA, IOWA, AND
OKLAHOMA, FRI-SAT, MAY 24-25.

RIVER FLOODING POSSIBLE ACROSS CENTRAL AND SOUTHWESTERN ALASKA, FRI-TUE, MAY
24-28.

RIVER FLOODING POSSIBLE IN WESTERN ALASKA, WED-TUE, MAY 29-JUNE 4.

RIVER FLOODING POSSIBLE IN SOUTHWESTERN ALASKA, WED-SAT, MAY 29-JUNE 1.

SEVERE DROUGHT FOR PARTS OF NORTHERN FLORIDA, GREAT PLAINS, RIO GRANDE VALLEY,
ROCKIES, SOUTHWEST, GREAT BASIN, CALIFORNIA, AND HAWAII.

DETAILED SUMMARY

FOR FRIDAY MAY 24 - TUESDAY MAY 28: AREAS OF HEAVY RAIN (2-3 INCHES) ARE
PREDICTED OVER THE CENTRAL CORN BELT DURING THIS PERIOD, IN ADVANCE OF A WARM
FRONT. WITH A 500-HPA TROUGH FORECAST OVER THE WEST, AND A 500-HPA RIDGE
FORECAST OVER THE CENTRAL CONUS, CHANCES OF GETTING SEVERE WEATHER ACROSS THE
CENTRAL GREAT PLAINS OR CRITICAL WILDFIRE AREAS IN THE SOUTHWEST ARE ELEVATED.
HOWEVER, THERE IS TOO MUCH UNCERTAINTY AT THIS TIME REGARDING THE TIMING OF
SHORT-WAVE TROUGHS EJECTING OUT OF THE WEST COAST LONG-WAVE TROUGH TO WARRANT A
SEVERE WEATHER AREA OR A CRITICAL WILDFIRE AREA ON THE MAP.



IN THE PAST WEEK, ANYWHERE FROM 2-6 INCHES OF RAIN HAVE FALLEN ACROSS NORTHERN
AND CENTRAL PORTIONS OF BOTH THE GREAT PLAINS AND THE MISSISSIPPI VALLEY.
BETWEEN 15-20 FLOOD AREAS ARE HIGHLIGHTED ON THE MAP OVER THE CENTRAL CONUS,
DUE TO THIS RECENT RAIN AND THE EXPECTATION OF MORE RAIN DURING THIS PERIOD.



WIND SPEEDS OF 20-30 KNOTS ARE EXPECTED ACROSS THE NORTHERN HIGH PLAINS EARLY
IN THE PERIOD, ASSOCIATED WITH A FAIRLY STRONG PRESSURE GRADIENT ACROSS THIS
REGION.



FAIRLY STRONG NORTHERLY AND NORTHWESTERLY WINDS (20-25 KNOTS) ARE ANTICIPATED
ALONG THE CENTRAL AND SOUTHERN COAST OF CALIFORNIA, RESULTING FROM A TIGHTENED
PRESSURE GRADIENT WITH HIGH PRESSURE OVER THE EASTERN PACIFIC AND LOW PRESSURE
OVER THE GREAT BASIN.



IN ALASKA, AN AREA OF LOW PRESSURE IS PREDICTED TO MOVE FROM THE FAR NORTHERN
PACIFIC NORTHWARD TO THE CENTRAL ALEUTIANS, WITH MUCH OF ITS ENERGY BEING
REDIRECTED EASTWARD INTO THE NORTHERN GULF OF ALASKA. CONCURRENTLY, AN AREA OF
HIGH PRESSURE IS ANTICIPATED OVER EASTERN PORTIONS OF ALASKA. MUCH ABOVE NORMAL
TEMPERATURES ARE PROJECTED FOR THE PANHANDLE REGION AND SOUTHEASTERN PART OF
THE MAINLAND. IN ADDITION, WITH THE EXPECTED CHANGE FROM UNSEASONABLY COLD TO
UNSEASONABLY WARM WEATHER, THERE ARE FLOODING CONCERNS ALONG MAJOR RIVERS (FOR
EXAMPLE, THE YUKON AND KUSKOKWIM RIVERS) IN CENTRAL AND SOUTHWESTERN ALASKA DUE
TO MELTING SNOW AND ICE JAMS. OF NOTE IS THE VERY RECENT BREAKUP OF RIVER ICE
IN THE TANANA RIVER NEAR NENANA, AK. THIS IS THE LATEST RECORDED RIVER ICE
BREAKUP FOR THE TANANA RIVER SINCE RECORD-KEEPING BEGAN IN 1917. THE PREVIOUS
RECORD WAS MAY 20, 1964.

FOR WEDNESDAY MAY 29 - TUESDAY JUNE 04: THE ONLY HAZARDOUS AREAS HIGHLIGHTED ON
THE WEEK 2 MAP AT THIS TIME ARE THE CONTINUING FLOOD AND DROUGHT AREAS. THERE
ARE TWO ITEMS WHICH WARRANT FURTHER MONITORING DURING THE NEXT FEW DAYS. THE
FIRST INVOLVES THE POTENTIAL FOR MUCH ABOVE NORMAL TEMPERATURES FROM THE
CENTRAL HIGH PLAINS EASTWARD ACROSS THE NORTH-CENTRAL MISSISSIPPI VALLEY AND
GREAT LAKES REGION. THE SECOND ITEM INVOLVES THE POSSIBILITY OF A TROPICAL
SYSTEM DEVELOPING OVER THE WESTERN CARIBBEAN AND MOVING NORTHWARD INTO THE GULF
OF MEXICO, AS INDICATED BY CPC`S GLOBAL TROPICS HAZARDS AND BENEFITS OUTLOOK
AT:

HTTP://WWW.CPC.NCEP.NOAA.GOV/PRODUCTS/PRECIP/CWLINK/GHAZARDS/IMAGES/GTH_FULL.PNG



ACCORDING TO THE U.S. DROUGHT MONITOR VALID MAY 14, SEVERE (D2) TO EXCEPTIONAL
(D4) DROUGHT COVERAGE ACROSS THE CONTINENTAL U.S. DECREASED SLIGHTLY TO 32
PERCENT WITH THE MOST IMPROVEMENT NOTED IN SOUTHERN MINNESOTA.

FORECASTER: ANTHONY ARTUSA

$$