Prognostic Meteorological Discussion
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FXUS21 KWNC 221744
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT MAY 22 2015

SYNOPSIS: A WARM, HUMID PATTERN IS FORECAST TO DOMINATE OVER PARTS OF THE
EASTERN U.S. DURING MUCH OF THE PERIOD, WHILE AN ACTIVE PATTERN IS FORECAST TO
CONTINUE OVER THE NATION`S MIDSECTION. UPPER-LEVEL HIGH PRESSURE IS EXPECTED TO
PERSIST OVER ALASKA DURING THE NEXT TWO WEEKS, WHILE A GRADUAL WARMING TREND IS
FORECAST OVER THE WESTERN U.S. EARLY IN THE PERIOD.

HAZARDS

HEAVY RAIN FROM SOUTHEASTERN TEXAS THROUGH THE LOWER MISSISSIPPI VALLEY,
MON-TUE, MAY 25-26.

HEAVY RAIN FOR PARTS OF THE CENTRAL AND SOUTHERN PLAINS, WED-THU, MAY 27-28.

MUCH ABOVE-NORMAL TEMPERATURES ARE EXPECTED FOR PARTS OF THE MID-ATLANTIC AND
NORTHEAST U.S., TUE-FRI, MAY 26-29.

FLOODING IS POSSIBLE, IMMINENT, OR OCCURRING IN PARTS OF THE CENTRAL AND
SOUTHERN GREAT PLAINS REGION AS WELL AS THE CENTRAL ROCKIES.

ENHANCED WILDFIRE RISK FOR INTERIOR EASTERN ALASKA, MON-FRI, MAY 25-JUNE 5.

SLIGHT RISK OF MUCH ABOVE-NORMAL TEMPERATURES FOR THE MID-ATLANTIC U.S., SAT,
MAY 30.

SEVERE DROUGHT FOR PARTS OF THE NORTHERN, CENTRAL AND SOUTHERN GREAT PLAINS,
UPPER MISSISSIPPI VALLEY, SOUTHWEST, GREAT BASIN, CALIFORNIA, AND THE PACIFIC
NORTHWEST.

DETAILED SUMMARY

FOR MONDAY MAY 25 - FRIDAY MAY 29: DURING THIS PERIOD, AN AMPLIFIED UPPER-LEVEL
TROUGH IS FORECAST TO LIFT NORTHEASTWARD OUT OF THE WEST-CENTRAL CONUS WHILE
WEAKENING, AND ROBUST UPPER-LEVEL RIDGING IS FORECAST TO PERSIST NEAR THE EAST
COAST. SURFACE LOW PRESSURE ASSOCIATED WITH THE FORMER IS EXPECTED TO MOVE
QUICKLY NORTHEASTWARD TOWARD THE GREAT LAKES, PRODUCING HEAVY RAIN IN THE WARM
SECTOR ACROSS SOUTHEASTERN TEXAS AND THE LOWER MISSISSIPPI VALLEY.
PRECIPITATION AMOUNTS OF 1-4 INCHES ARE FORECAST FOR THE AREA DEPICTED ON THE
MAP OVER A 2-DAY PERIOD.



GIVEN THE RECENT HEAVY RAINFALL OVER THE CENTRAL AND SOUTHERN PLAINS, WITH MORE
ANTICIPATED EVEN BEFORE THE START OF THIS PERIOD, SATURATED SOILS WILL
UNDOUBTEDLY LEAD TO FLOODING AREAS. OTHER SMALL AREAS OF FLOODING ARE DEPICTED
IN PARTS OF COLORADO AND NEBRASKA. DUE TO THE FREQUENT AND OFTEN RAPID CHANGES
IN FLOOD AREAS DESIGNATED ON THE HAZARDS MAP, IT IS RECOMMENDED THAT RESIDENTS
CONSULT THE VERY LATEST INFORMATION AT THE RIVER FORECAST CENTER (RFC) HOMEPAGE
AT HTTP://WATER.WEATHER.GOV/AHPS/RFC/RFC.PHP



A WEAKER SHORTWAVE IS FORECAST TO MOVE THROUGH THE MEAN TROUGH CENTERED NEAR
THE ROCKIES LATER IN THE PERIOD. THIS IS EXPECTED TO TRIGGER ANOTHER ROUND OF
LOCALLY HEAVY RAINFALL FOR PARTS OF THE CENTRAL AND SOUTHERN PLAINS BY NEXT
WEDNESDAY AND THURSDAY. THERE IS STILL A FAIR AMOUNT OF UNCERTAINTY WITH THIS
FEATURE, SO IT WILL BE IMPORTANT TO MONITOR THE NEXT HAZARDS UPDATE ON MONDAY
FOR THE LATEST INFORMATION.



STRONG TO SEVERE THUNDERSTORMS MAY ALSO DEVELOP DURING THIS PERIOD ACROSS
CENTRAL AND SOUTHERN PORTIONS OF BOTH THE PLAINS AND MISSISSIPPI VALLEY. FAIRLY
POOR RUN-TO-RUN CONTINUITY AMONG VARIOUS DYNAMICAL MODELS, REGARDING THE TIMING
OF INDIVIDUAL SHORT-WAVE FEATURES EXPECTED TO MOVE THROUGH THIS REGION,
PRECLUDES THE DESIGNATION OF A SEVERE WEATHER AREA ON THE MAP AT THIS TIME.



AS AN UPPER-LEVEL RIDGE BUILDS OVER THE SOUTHEAST COAST, HOT AND HUMID
CONDITIONS ARE FORECAST TO RETURN TO PARTS OF THE EASTERN CONUS DURING THE
PERIOD. HIGH TEMPERATURES COULD EXCEED 90 DEGREES FOR THREE OR MORE CONSECUTIVE
DAYS OVER THE DEPICTED REGION, FOLLOWING A WARM FRONTAL PASSAGE ON MONDAY. THE
HAZARD IS DEPICTED OVER THE REGION WHERE MAXIMUM DAYTIME TEMPERATURES ARE
FORECAST TO BE GREATER THAN 10 DEGREES ABOVE NORMAL AND APPROACH OR EXCEED 90
DEGREES.



IN THE EASTERN INTERIOR OF ALASKA, CONTINUED WARM, DRY, AND BREEZY CONDITIONS
FAVOR AN INCREASED CHANCE OF CRITICAL WILDFIRE CONDITIONS THROUGHOUT THIS
PERIOD, AS WELL AS THE ENSUING WEEK-2 PERIOD.

FOR SATURDAY MAY 30 - FRIDAY JUNE 05: THE EXPECTED MID-TROPOSPHERIC FLOW
PATTERN FOR WEEK-2 FEATURES AN AMPLIFIED RIDGE OVER WESTERN CANADA AND ALASKA,
AND A DEEP TROUGH OVER EASTERN NORTHEASTERN CANADA. A LESS-AMPLIFIED PATTERN IS
PREDICTED OVER THE CONUS (ESPECIALLY COMPARED TO HIGHER LATITUDES), WITH A
CLIMATOLOGICAL TROUGH CENTERED OVER CALIFORNIA, AND QUASI-ZONAL FLOW DOWNSTREAM
OVER THE REMAINDER OF THE CONUS.



THE ENHANCED RISK OF WILDFIRES NOTED FOR EASTERN INTERIOR ALASKA DURING THE 3-7
DAY PERIOD IS LIKELY TO EXTEND THROUGHOUT MOST, IF NOT ALL, OF WEEK-2. WELL
ABOVE-AVERAGE TEMPERATURES AND BELOW-MEDIAN PRECIPITATION ARE ANTICIPATED
DURING THIS PERIOD, ASSOCIATED WITH THE PREDICTED PERSISTENCE OF AN ANOMALOUS
MID-TROPOSPHERIC RIDGE.



WARM AND HUMID CONDITIONS ARE MORE THAN LIKELY GOING TO PERSIST ACROSS PARTS OF
THE EASTERN CONUS, AT LEAST EARLY IN THE PERIOD, WHERE A SLIGHT RISK OF MUCH
ABOVE-NORMAL TEMPERATURES IS INDICATED OVER THE MID-ATLANTIC.



THE MOST RECENT U.S. DROUGHT MONITOR, RELEASED YESTERDAY, INDICATES A
SUBSTANTIAL DECREASE (FROM 17.68 TO 15.16) IN THE PERCENTAGE OF THE CONUS IN
SEVERE TO EXCEPTIONAL DROUGHT (D2-D4).

FORECASTER: STEPHEN BAXTER

$$




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