Valid Monday, May 27, 2013 to Friday, June 07, 2013

Summary of Forecasts and Hazards

US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT MAY 24 2013

SYNOPSIS: *** HAZARDS WILL BE UPDATED BY MID-AFTERNOON ***
AT THE START OF THE PERIOD, A LOW PRESSURE CENTER IS FORECAST NEAR CAPE COD. THE ASSOCIATED COLD FRONT IS PREDICTED TO EXTEND SOUTHWARD FROM THIS LOW TO THE SOUTHERN ATLANTIC COAST, CONTINUING INLAND AS A STATIONARY FRONT ACROSS THE INTERIOR GULF COAST STATES, LOWER MISSISSIPPI VALLEY, AND SOUTH-CENTRAL PLAINS. HIGH PRESSURE IS EXPECTED TO BUILD IN BEHIND THIS FRONT ACROSS MOST OF THE EASTERN HALF OF THE CONTIGUOUS UNITED STATES. BY THE MIDDLE OF THE HAZARDS OUTLOOK, ONE FRONTAL SYSTEM IS ANTICIPATED OVER THE NORTH-CENTRAL STATES, WHILE ANOTHER TRAVERSES THE PACIFIC NORTHWEST. IN ALASKA, A LOW PRESSURE SYSTEM EXTENDING FROM THE CENTRAL ALEUTIANS TO THE CENTRAL GULF OF ALASKA IS PREDICTED TO MIGRATE SOUTHEASTWARD TOWARD VANCOUVER AND WASHINGTON STATE.

HAZARDS

• *** HAZARDS WILL BE UPDATED BY MID-AFTERNOON ***
• HEAVY RAIN FOR CENTRAL AND WESTERN PORTIONS OF THE CORN BELT, SUN-MON, MAY 26-27.
• HIGH WINDS ALONG THE MID-ATLANTIC AND NEW ENGLAND COASTS, SUN, MAY 26.
• MUCH ABOVE NORMAL TEMPERATURES FOR THE ALASKA PANHANDLE AND MUCH OF THE EASTERN MAINLAND, SUN-THU, MAY 26-30.
• RIVER FLOODING OCCURRING OR IMMINENT IN NORTHERN NORTH DAKOTA, PARTS OF THE MIDDLE MISSISSIPPI VALLEY, AND SOUTHEASTERN OKLAHOMA, SUN-MON, MAY 26-27.
• RIVER FLOODING LIKELY IN NORTHERN NORTH DAKOTA AND EASTERN IOWA, SUN-MON, MAY 26-27.
• RIVER FLOODING POSSIBLE FOR IOWA AND LOWER MICHIGAN, SUN-MON, MAY 26-27.
• RIVER FLOODING POSSIBLE ACROSS CENTRAL AND SOUTHWESTERN ALASKA, SUN-THU, MAY 26-30.
• RIVER FLOODING POSSIBLE IN WESTERN ALASKA, FRI-THU, MAY 31-JUNE 6.
• RIVER FLOODING POSSIBLE IN SOUTHWESTERN ALASKA, FRI-MON, MAY 31-JUNE 3.
• SEVERE DROUGHT FOR PARTS OF NORTHERN FLORIDA, GREAT PLAINS, RIO GRANDE VALLEY, ROCKIES, SOUTHWEST, GREAT BASIN, CALIFORNIA, AND HAWAII.

DETAILED SUMMARY

FOR MONDAY MAY 27 - FRIDAY MAY 31: *** HAZARDS WILL BE UPDATED BY MID-AFTERNOON ***
AN AREA OF HEAVY RAIN (NEAR 2 INCHES) IS PREDICTED OVER CENTRAL AND WESTERN SECTIONS OF THE CORN BELT DURING THE FIRST TWO DAYS OF THIS PERIOD, IN ADVANCE OF A WARM FRONT. THOUGH A MID-TROPOSPHERIC TROUGH IS FORECAST OVER THE WEST, AND A RIDGE OVER THE CENTRAL CONUS, THERE IS SIGNIFICANT UNCERTAINTY ASSOCIATED WITH THE ANTICIPATED EVOLUTION OF THE CIRCULATION PATTERN DURING THIS PERIOD. A MAJOR PROBLEM WITH THIS TYPE OF 500-HPA FLOW PATTERN IS TRYING TO PREDICT THE TIMING OF SHORT-WAVE TROUGHS EMBEDDED IN SOUTHWESTERLY FLOW. IT IS LARGELY FOR THIS REASON THAT NO SEVERE WEATHER AREAS OR ENHANCED WILDFIRE AREAS ARE CURRENTLY DESIGNATED ON THE MAP.

IN THE PAST WEEK, ANYWHERE FROM 2-6 INCHES OF RAIN HAVE FALLEN ACROSS NORTHERN AND SOUTH-CENTRAL PORTIONS OF BOTH THE GREAT PLAINS AND THE MISSISSIPPI VALLEY. ABOUT 10 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.

AT THE BEGINNING OF THE HAZARDS OUTLOOK, A COLD FRONT JUST OFF THE EAST COAST IS EXPECTED TO MOVE SLOWLY OUT TO SEA. A WAVE OF LOW PRESSURE IS FORECAST TO BE SITUATED ALONG THIS FRONT NEAR CAPE COD. AS THIS LOW DEEPENS, NORTHWESTERLY WINDS OF 20-30 KNOTS ARE EXPECTED ALONG THE MID-ATLANTIC AND NEW ENGLAND COASTS, HELPING TO ADVECT UNSEASONABLY CHILLY AIR INTO THE NORTHEAST FOR THE MEMORIAL DAY WEEKEND.

IN ALASKA, AN AREA OF LOW PRESSURE FROM THE CENTRAL ALEUTIANS TO THE CENTRAL GULF OF ALASKA IS ANTICIPATED TO TRACK SOUTHEASTWARD TOWARD VANCOUVER ISLAND AND WASHINGTON STATE. A SURFACE RIDGE OF HIGH PRESSURE IS FORECAST OVER SOUTHEASTERN PORTIONS OF ALASKA. MUCH ABOVE NORMAL TEMPERATURES ARE PROJECTED FOR THE PANHANDLE REGION AND A LARGE PORTION OF THE EASTERN 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, KUSKOKWIM, AND KOYUKUK RIVERS) IN CENTRAL AND SOUTHWESTERN ALASKA. WITH SUCH A LATE START TO THE SPRING MELT SEASON, AND A SIGNIFICANTLY HIGHER SUN ANGLE, IT IS REASONABLE TO EXPECT A SHORT-LIVED BUT FAIRLY INTENSE PERIOD OF RAPID SNOW MELT AND ICE JAMS IN ALASKA. 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 SET ON MAY 20, 1964.

FOR SATURDAY JUNE 01 - FRIDAY JUNE 07: *** HAZARDS WILL BE UPDATED BY MID-AFTERNOON ***
THE ONLY HAZARDOUS AREAS HIGHLIGHTED ON THE WEEK 2 MAP AT THIS TIME ARE THE CONTINUING FLOOD AND SEVERE DROUGHT AREAS. THERE ARE TWO ITEMS WHICH CONTINUE TO BE MONITORED. 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. HOWEVER, DIFFERING DYNAMICAL MODEL SOLUTIONS MAKE IT UNCLEAR AS TO THE STRENGTH AND THE DEGREE OF EASTWARD PROGRESSION OF THE UPPER-LEVEL RIDGE OVER THE CENTRAL CONUS. MOST LOCATIONS WITHIN THE NOTED REGION ARE PREDICTED TO EXPERIENCE TEMPERATURE ANOMALIES BETWEEN 8-12 DEGREES ABOVE NORMAL, WHICH IS AT BEST A MARGINAL HAZARD. 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

THE RELEASE OF THE U.S. DROUGHT MONITOR THIS MORNING(MAY 23)REVEALS MOSTLY MINOR ADJUSTMENTS WERE RENDERED TO LAST WEEK'S DROUGHT DEPICTION. THE MORE SIGNIFICANT CHANGES INCLUDED FURTHER DEGRADATION ACROSS THE SOUTHERN HIGH PLAINS, AND CONTINUED IMPROVEMENT ACROSS THE NORTH-CENTRAL CONUS. IN ADDITION, SEVERE TO EXCEPTIONAL (D2-D4) DROUGHT IS AT ITS LOWEST COVERAGE ACROSS THE CONUS SINCE JUNE 26, 2012 (ABOUT THE TIME WHEN THE FLASH DROUGHT WAS RAMPING UP LAST YEAR).

FORECASTER: ANTHONY ARTUSA

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