Prognostic Meteorological Discussion
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FXUS21 KWNC 031750
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT JULY 03 2015

SYNOPSIS: DURING THE NEXT WEEK, THE STRONG AREA OF UPPER-LEVEL HIGH PRESSURE IS
EXPECTED TO GRADUALLY WEAKEN ACROSS THE PACIFIC NORTHWEST. AS AN AREA OF
UPPER-LEVEL LOW PRESSURE APPROACHES THE WEST COAST, WESTERLY FLOW IS FORECAST
TO SHIFT MONSOON MOISTURE EAST OF THE DESERT SOUTHWEST. A COLD FRONT IS
FORECAST TO SLOW AS IT PROGRESSES SOUTHEAST FROM THE GREAT PLAINS TO THE
MISSISSIPPI VALLEY EARLY IN THE PERIOD. UPPER-LEVEL HIGH PRESSURE IS EXPECTED
TO PERSIST ACROSS THE EASTERN HALF OF ALASKA AT LEAST THROUGH THE NEXT WEEK.

HAZARDS

MUCH ABOVE-NORMAL TEMPERATURES FOR PARTS OF THE PACIFIC NORTHWEST, MON-TUE, JUL
6-7.

HEAVY RAIN FOR PARTS OF EASTERN ARIZONA, COLORADO, AND NEW MEXICO, MON-TUE, JUL
6-7.

HEAVY RAIN FOR PARTS OF THE CENTRAL/SOUTHERN GREAT PLAINS, MIDDLE MISSISSIPPI
VALLEY, AND GREAT LAKES, MON-TUE, JUL 6-7.

ENHANCED WILDFIRE RISK FOR PARTS OF MAINLAND ALASKA, MON-FRI, JUL 6-17.

ONGOING OR LIKELY FLOODING ACROSS PARTS OF THE MIDDLE MISSISSIPPI VALLEY.

SEVERE DROUGHT FOR PARTS OF THE WESTERN THIRD OF THE CONUS, SOUTHEAST GEORGIA,
AND SOUTH FLORIDA.

DETAILED SUMMARY

FOR MONDAY JULY 06 - FRIDAY JULY 10: MUCH ABOVE-NORMAL TEMPERATURES (12 TO 16
DEGREES F) ARE FORECAST TO PERSIST THROUGH TUESDAY ACROSS THE PACIFIC
NORTHWEST. FOLLOWING AN EXTENDED PERIOD OF UNSEASONABLY HOT TEMPERATURES, A
DECREASE IN 500-HPA HEIGHTS IS EXPECTED TO PROVIDE HEAT RELIEF LATE IN THIS
PERIOD.



AN AMPLIFIED UPPER-LEVEL TROUGH OVER CENTRAL CANADA IS EXPECTED TO RESULT IN A
COLD FRONT ADVANCING SOUTHEAST ACROSS THE GREAT LAKES, MISSISSIPPI VALLEY, AND
CENTRAL/SOUTHERN GREAT PLAINS. HEAVY RAIN (1 TO 2 INCHES, LOCALLY MORE) IS
FORECAST TO ACCOMPANY THE COLD FRONT ON MONDAY AND TUESDAY ACROSS THESE AREAS.



ON WEDNESDAY AND THURSDAY, THE FRONT MAY RETURN NORTH, PROVIDING A FOCUS FOR
CONVECTION WITH HEAVY RAIN ACROSS THE MIDWEST. HOWEVER, LARGE MODEL DIFFERENCES
PRECLUDE DESIGNATION OF A HEAVY RAIN HAZARD BEYOND TUESDAY. SEVERE WEATHER
POTENTIAL APPEARS MARGINAL WITH ANY CONVECTION ACROSS THE EAST-CENTRAL U.S.
THROUGHOUT THIS PERIOD DUE TO WEAK LAPSE RATES. DAILY CONVECTION, ASSOCIATED
WITH A MID-LEVEL TROUGH, IS EXPECTED ACROSS THE SIERRAS.



HEAVY RAIN (LOCAL AMOUNTS EXCEEDING 1 INCH) IS FORECAST ACROSS PARTS OF EASTERN
ARIZONA, COLORADO, AND NEW MEXICO ON MONDAY AND TUESDAY DUE TO MONSOONAL
MOISTURE COUPLED WITH UPSLOPE FLOW BEHIND A COLD FRONT. LOCALLY HEAVY RAIN MAY
TRIGGER FLASH FLOODING ALONG THE EASTERN SLOPES OF THE CONTINENTAL DIVIDE.
DURING THE REMAINDER OF THE WEEK, AN INCREASE IN WESTERLY FLOW IS EXPECTED TO
REDUCE MONSOON MOISTURE THROUGHOUT THE SOUTHWEST.



MODERATE TO MAJOR RIVER FLOODING ALONG THE ILLINOIS AND MIDDLE MISSISSIPPI
RIVER IS EXPECTED TO PERSIST INTO THE EARLY PART OF THIS PERIOD.



WARM AND DRY CONDITIONS ARE ANTICIPATED ACROSS MUCH OF MAINLAND ALASKA,
MAINTAINING AN ENHANCED WILDFIRE RISK ACROSS PARTS OF THIS AREA DURING THIS
PERIOD AS WELL AS WEEK-2. ACTIVE WEATHER IS LIKELY OVER THE ALEUTIANS DURING
THE PERIOD, THOUGH NO ADDITIONAL HAZARD DEPICTION IS WARRANTED. AS OF JULY 3,
WILDFIRES HAVE BURNED MORE THAN 2 MILLION ACRES ACROSS ALASKA DURING 2015.

FOR SATURDAY JULY 11 - FRIDAY JULY 17: THE 6Z GFS AND 0Z ECMWF ENSEMBLE MEANS
ON JULY 3 INDICATE A SUBTROPICAL RIDGE CENTERED OVER THE SOUTH-CENTRAL U.S., A
TROUGH ALONG THE WEST COAST, AND A RIDGE OVER NORTHEAST ALASKA. 500-HPA HEIGHT
ANOMALIES ARE FORECAST TO BE SMALL ACROSS THE LOWER 48 WHICH REDUCES THE RISK
OF A HEAT WAVE DURING EARLY TO MID-JULY. WESTERLY FLOW ALOFT IS EXPECTED TO
LIMIT RAINFALL AMOUNTS ASSOCIATED WITH THE MONSOON ACROSS THE SOUTHWEST. LATER
IN WEEK-2, THE GFS MODEL FAVORS TROPICAL CYCLONE DEVELOPMENT ACROSS THE EAST
PACIFIC.



THE ENHANCED FIRE WEATHER HAZARD IN ALASKA CONTINUES DURING THIS PERIOD. THIS
IS DUE IN PART TO THE POTENTIAL FOR INCREASED CONVECTION, WHICH CAN CONTRIBUTE
TO A RISK OF WILDFIRES CAUSED BY CLOUD TO GROUND LIGHTNING STRIKES.



THE MOST RECENT U.S. DROUGHT MONITOR, VALID ON JUNE 30, INDICATES AN INCREASE
(FROM 14.31 TO 15.54) IN THE PERCENTAGE OF THE CONUS IN SEVERE TO EXCEPTIONAL
DROUGHT (D2-D4). DROUGHT INTENSIFICATION (IMPROVEMENT) WAS OBSERVED OVER PARTS
OF THE NORTHWEST AND SOUTHEAST (MID-ATLANTIC AND NORTHEAST).

FORECASTER: BRAD PUGH

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