Prognostic Meteorological Discussion
Issued by NWS

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108
FXUS21 KWNC 261828
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT MAY 26 2017

SYNOPSIS: A COLD FRONT IS FORECAST TO REACH THE GULF COAST REGION AND THEN
STALL DURING THE 3-7 DAY PERIOD. ANOTHER COLD FRONT IS EXPECTED TO FOLLOW ON
ITS HEELS, AND TO REINFORCE THE FIRST FRONT. THIS GENERAL BOUNDARY IS PREDICTED
TO BE THE PRIMARY FOCUS FOR SHOWERS AND THUNDERSTORMS FOR DURING THE 3-7 DAY
PERIOD. A MID-LEVEL RIDGE OF HIGH PRESSURE OVER THE PACIFIC NORTHWEST EARLY IN
THE OUTLOOK PERIOD IS FORECAST TO SHIFT EASTWARD INTO THE NORTHERN GREAT PLAINS
REGION BY THE MIDDLE OF THE PERIOD, ACCOMPANIED BY RELATIVELY WARM SURFACE
TEMPERATURES. IN ALASKA, A RELATIVELY QUIET WEATHER PATTERN IS ANTICIPATED
DURING THE 3-7 DAY PERIOD. A LOW PRESSURE SYSTEM OVER THE CENTRAL GULF OF
ALASKA IS FORECAST TO TRACK TOWARDS THE ALEUTIANS, REACHING THE ARCHIPELAGO BY
THE MIDDLE OF THE OUTLOOK PERIOD.

HAZARDS

HEAVY RAIN FOR PORTIONS OF TEXAS, MON-TUE, MAY 29-30.

HEAVY RAIN FROM WEST-CENTRAL TEXAS TO SOUTHWESTERN MISSOURI, WED-THU, MAY
31-JUN 1.

MUCH ABOVE-NORMAL TEMPERATURES FOR PARTS OF NORTHERN CALIFORNIA AND THE PACIFIC
NORTHWEST, MON-TUE, MAY 29-30.

FLOODING OCCURRING, IMMINENT, LIKELY OR POSSIBLE FOR PARTS OF THE MISSISSIPPI
VALLEY, THE NORTHERN AND CENTRAL INTERMOUNTAIN REGION, AND THE NORTHERN ROCKIES.

SEVERE DROUGHT ACROSS PARTS OF THE SOUTHEAST, TEXAS, AND SOUTHERN CALIFORNIA.

DETAILED SUMMARY

FOR MONDAY MAY 29 - FRIDAY JUNE 02: REINFORCING COLD FRONTS DRAPED ACROSS THE
GULF COAST STATES ARE EXPECTED TO BRING SHOWERS AND THUNDERSTORMS TO PORTIONS
OF THE SOUTHERN PLAINS, LOWER AND MIDDLE MISSISSIPPI VALLEY, TENNESSEE VALLEY,
AND THE SOUTHEAST. HOWEVER, ONLY TWO AREAS OF HAZARDOUS, HEAVY RAINFALL ARE
ANTICIPATED. THE FIRST PREDICTED AREA OF HEAVY RAINFALL IS IN THE SOUTHWESTERN
PORTION OF TEXAS, WHERE AMOUNTS OF 1-3 INCHES ARE GENERALLY EXPECTED, BUT
LOCALLY UP TO 6 INCHES NEAR DEL RIO, ON MAY 29-30. THE SECOND PREDICTED AREA OF
HEAVY RAINFALL EXTENDS FROM WEST-CENTRAL TEXAS TO SOUTHWESTERN MISSOURI (1-3
INCHES, MAY 31-JUN 1).



A MID-LEVEL RIDGE OVER THE PACIFIC NORTHWEST AND NORTHERN CALIFORNIA IS
EXPECTED TO CONTRIBUTE TO WELL ABOVE-NORMAL TEMPERATURES ACROSS PARTS OF THE
REGION. THE HIGHLIGHTED REGION ON THE MAP DEFINES WHERE MAXIMUM TEMPERATURES
ARE FORECAST TO RANGE FROM 12-20 DEGREES F ABOVE NORMAL, AND WARM TO 90-95
DEGREES F, ON MAY 29-30. THESE HOT TEMPERATURES ARE LIKELY TO RESULT IN RAPID
SNOW MELT, LEADING TO INCREASED RUNOFF AND FLOWS ALONG RIVERS AND STREAMS
THROUGHOUT THE PACIFIC NORTHWEST AND NORTHERN GREAT BASIN.



RAINFALL, PRIOR TO THIS PERIOD, COUPLED WITH SATURATED SOILS MAY RESULT IN A
RENEWAL OF FLOODING ACROSS PARTS OF THE MISSISSIPPI RIVER VALLEY.  THE LOWER
PORTION OF THE MISSISSIPPI RIVER VALLEY IS FORECAST TO CREST EARLY NEXT WEEK,
BUT HEAVY RAINFALL FORECAST DURING THE NEXT WEEK COULD PROLONG FLOODING. PLEASE
NOTE THAT THESE FLOOD SHAPES MAY CHANGE FAIRLY FREQUENTLY; THEREFORE, FOR THE
VERY LATEST GRAPHICS, WE RECOMMEND CONSULTING THE RIVER FORECAST CENTER (RFC)
WEBSITE AT: HTTP://WATER.WEATHER.GOV/AHPS/RFC/RFC.PHP



LATE IN THIS PERIOD, A BRIEF DOWNSLOPE EVENT IS ANTICIPATED ACROSS EASTERN
MONTANA, WHICH IS EXPECTED TO RESULT IN DAYTIME TEMPERATURES AT, OR SLIGHTLY
ABOVE, 85 DEGREES F ON JUN 1-2.

FOR SATURDAY JUNE 03 - FRIDAY JUNE 09: TODAY`S DYNAMICAL MODELS GENERALLY
PREDICT A DE-AMPLIFIED RIDGE, WITH MORE WESTERLY FLOW, OVER THE PACIFIC
NORTHWEST, WHICH WOULD TEND TO REDUCE THE MAGNITUDE OF POSITIVE TEMPERATURE
ANOMALIES ANTICIPATED OVER THE REGION. THEY ALSO FORECAST A WEAK, UNDERCUTTING
TROUGH OVER THE CENTRAL BASIN, AND A FULL-LATITUDE TROUGH OVER EASTERN NORTH
AMERICA.



UNCERTAINTY BETWEEN MODEL SOLUTIONS PRECLUDES THE DESIGNATION OF A HEAVY
PRECIPITATION AREA OVER PORTIONS OF THE LOWER 48 STATES DURING WEEK-2.



THE U.S. DROUGHT MONITOR RELEASED ON MAY 25TH SHOWS D2-D4 DROUGHT COVERAGE OVER
THE CONUS NOW AT 1.22%, A SLIGHT DECREASE FROM 1.38% ONE WEEK AGO. THE ONLY
AREAS OF THE COUNTRY THAT HAVE D2 (OR WORSE) CONDITIONS INCLUDE PARTS OF THE
SOUTHEAST, THE SOUTHERN TIP OF TEXAS, AND EXTREME SOUTHEASTERN CALIFORNIA.

FORECASTER: ANTHONY ARTUSA

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