Prognostic Meteorological Discussion
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FXUS21 KWNC 281911
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT JUNE 28 2016

SYNOPSIS: AT THE BEGINNING OF THE FORECAST PERIOD, A STATIONARY FRONT IS
ANTICIPATED TO EXTEND FROM THE SOUTHERN PLAINS EASTWARD THROUGH THE
MID-ATLANTIC.  EARLY IN WEEK-1 A COLD FRONT IS FORECAST TO DESCEND SOUTHWARD
THROUGH THE PLAINS, AND MERGE WITH THE AFOREMENTIONED BOUNDARY.  PERIODIC
DISTURBANCES ARE EXPECTED TO RIDE ALONG THIS STATIONARY FRONT BRINGING HEAVY
RAINFALL TO THE CENTRAL PLAINS AND OHIO VALLEY.  MID-LEVEL HIGH PRESSURE IS
FORECAST SOUTH AND WEST OF THIS FRONTAL ACTIVITY, WITH HEAT-RELATED HAZARDS
POSSIBLE IN THE LATTER HALF OF WEEK-1.  MID-LEVEL HIGH PRESSURE IS GENERALLY
FORECAST FOR THE CONUS DURING WEEK-2.  PERIODIC WEAK DISTURBANCES ARE
ANTICIPATED TO IMPACT SOUTHERN ALASKA DURING BOTH WEEKS 1 AND 2.

HAZARDS

HEAVY RAIN ACROSS PORTIONS OF THE CENTRAL PLAINS, THE CENTRAL APPALACHIANS, THE
TENNESSEE VALLEY, THE MIDDLE MISSISSIPPI VALLEY, THE SOUTHERN APPALACHIANS, THE
GREAT LAKES, AND THE OHIO VALLEY, SAT-MON, JUL 2-JUL 4.

HEAVY RAIN ACROSS PORTIONS OF THE MID-ATLANTIC, SUN-MON, JUL 3-JUL 4.

FLOODING OCCURRING OR IMMINENT ACROSS PORTIONS OF THE SOUTHERN PLAINS, FRI-SAT,
JUL 1-JUL 2.

FLOODING LIKELY ACROSS PORTIONS OF THE SOUTHERN PLAINS, FRI-SAT, JUL 1-JUL 2.

EXCESSIVE HEAT ACROSS PORTIONS OF CALIFORNIA AND THE SOUTHWEST, SUN-TUE, JUL
3-JUL 5.

EXCESSIVE HEAT ACROSS PORTIONS OF THE SOUTHERN PLAINS, SAT-TUE, JUL 2-JUL 5.

MODERATE RISK OF MUCH ABOVE-NORMAL TEMPERATURES FOR PORTIONS OF THE SOUTHERN
PLAINS, WED, JUL 6.

SLIGHT RISK OF MUCH ABOVE-NORMAL TEMPERATURES FOR PORTIONS OF THE CENTRAL
PLAINS, THE LOWER MISSISSIPPI VALLEY, THE NORTHERN PLAINS, THE MIDDLE
MISSISSIPPI VALLEY, THE UPPER MISSISSIPPI VALLEY, AND THE SOUTHERN PLAINS, WED,
JUL 6.

SLIGHT RISK OF MUCH ABOVE-NORMAL TEMPERATURES FOR PORTIONS OF THE CENTRAL GREAT
BASIN, CALIFORNIA, THE NORTHERN GREAT BASIN, AND THE SOUTHWEST, SAT-TUE, JUL
9-JUL 12.

SEVERE DROUGHT ACROSS THE CENTRAL GREAT BASIN, THE NORTHERN PLAINS, THE
TENNESSEE VALLEY, HAWAII, THE MID-ATLANTIC, CALIFORNIA, THE SOUTHEAST, THE
SOUTHERN APPALACHIANS, AND THE SOUTHWEST.

DETAILED SUMMARY

FOR FRIDAY JULY 01 - TUESDAY JULY 05: AT THE BEGINNING OF WEEK-1, 500-HPA
RIDGING IS FORECAST ACROSS THE WESTERN CONUS WITH TROUGHING THROUGH THE GREAT
LAKES.  OVER THE COURSE OF THE WEEK THE PATTERN IS EXPECTED TO PROGRESS
EASTWARD AND FLATTEN OUT SLIGHTLY, WITH THE GREATEST POSITIVE HEIGHT ANOMALIES
FORECAST THROUGH THE NORTHERN ROCKIES AND PLAINS.  SOUTH OF THESE FORECAST
HEIGHT ANOMALIES A STATIONARY FRONT IS FORECAST TO BE PRESENT ACCOMPANIED BY
PERSISTENT HEAVY RAINFALL (EXCEEDING 1" IN 24 HOURS) ACROSS THE CENTRAL PLAINS
AND MIDDLE-OHIO VALLEY SATURDAY-MONDAY, JULY 2-4.  THIS PRECIPITATION IS
EXPECTED TO SHIFT ITS FOCAL REGION SLOWLY EASTWARD DURING THIS 3-DAY PERIOD.
NO SEVERE WEATHER THREATS ARE INDICATED ON THE FORECAST MAP, BUT ANY SEVERE
WEATHER EARLY IN WEEK-1 WOULD LIKELY BE COLLOCATED WITH THIS HEAVY
PRECIPITATION REGION.  FURTHER EAST ALONG THE STATIONARY BOUNDARY, A SECOND
REGION OF HEAVY RAINFALL IS POSSIBLE FOR EASTERN NORTH CAROLINA ON SUNDAY, JULY
3 AND MONDAY, JULY 4.  A REGION LINKING THE TWO HEAVY RAINFALL SHAPES WAS
CONSIDERED, HOWEVER THE 12Z GFS SHIFTED SEVERAL HUNDRED MILES FURTHER NORTH AND
EAST WITH THIS RAINFALL RELATIVE TO THE PRIOR TWO RUNS, WHILE THE 0Z ECMWF IS
MUCH FURTHER SOUTH WITH THIS PRECIPITATION.  INCREASED CONSISTENCY BETWEEN THE
TWO MODELS FOR DELINEATION OF A HAZARD WILL BE SOUGHT IN UPCOMING FORECASTS
GIVEN THE CURRENTLY DIVERGING SOLUTIONS.



OUTSIDE OF THE HEAVY RAINFALL IMPACTS FROM THE STATIONARY FRONT, HEAT AND
FIRE-RELATED HAZARDS ARE POSSIBLE IN THE SOUTH AND WEST.  ACROSS PORTIONS OF
THE SOUTHERN PLAINS ON SATURDAY, JULY 2 THROUGH TUESDAY, JULY 5, EXCESSIVE HEAT
IS FORECAST, WITH INITIAL CONCERN ACROSS THE SOUTHERN PARTS OF THIS SHAPE
BEFORE INCREASING NORTH AND EAST DURING THE PERIOD.  HERE, TEMPERATURES ARE
FORECAST TO GENERALLY BE IN THE MID- TO UPPER-90S, BUT MOIST
SOUTH-SOUTHEASTERLY FLOW OFF THE GULF OF MEXICO IS ANTICIPATED TO DRIVE THE
HEAT INDEX TO 105-110 DEGREES FAHRENHEIT.  A SECOND REGION OF EXCESSIVE HEAT IS
FORECAST ACROSS THE SOUTHWEST SUNDAY, JULY 3 THROUGH TUESDAY, JULY 5, WHERE
MAXIMUM TEMPERATURES ARE FORECAST TO APPROACH OR EXCEED 110 DEGREES FAHRENHEIT.
 ALSO ACROSS THE WEST ELEVATED RISKS OF FIRE WEATHER ARE POSSIBLE FOR PORTIONS
OF THE INTERIOR PACIFIC NORTHWEST ON FRIDAY, JULY 1 AND SOUTHERN CALIFORNIA
FRIDAY, JULY 1 THROUGH SUNDAY, JULY 3, ASSOCIATED WITH DRY CONDITIONS AND
POTENTIALLY STRONG, BUT NON-HAZARDOUS, WINDS.



PERIODIC DISTURBANCES ARE EXPECTED TO IMPACT ALASKA DURING WEEK-1, WITH NO
HAZARDS CURRENTLY ANTICIPATED.  THE GEFS AND OPERATIONAL GFS DO SUPPORT
POTENTIAL FOR 24-HOUR RAINFALL EXCEEDING 3" ACROSS PORTIONS OF THE ALASKA RANGE
EARLY IN WEEK-1; HOWEVER, THE ECMWF PROJECTS THIS PRECIPITATION TO BE FURTHER
NORTH AND WEST WHILE FAILING TO APPROACH HAZARDS CRITERIA.

FOR WEDNESDAY JULY 06 - TUESDAY JULY 12: RIDGING AT 500-HPA IS FORECAST ACROSS
THE CONUS DURING WEEK-2, WITH THE GREATEST POSITIVE HEIGHT ANOMALIES ACROSS THE
NORTHERN TIER, WITH THE GEFS BEING SLIGHTLY MORE AMPLIFIED THAN THE ECMWF.
OVER THE COURSE OF THE WEEK THIS RIDGE IS FORECAST TO RETROGRADE WESTWARD
SOMEWHAT, BECOMING FOCUSED ACROSS THE SOUTHERN ROCKIES.  FOR WEDNESDAY, JULY 6
A SLIGHT AND MODERATE RISK OF MUCH-ABOVE NORMAL TEMPERATURES IS FORECAST ACROSS
MUCH OF THE GREAT PLAINS BENEATH THE RIDGE-AXIS, WHERE THE GEFS PROBABILISTIC
EXTREMES TOOL INDICATES A GREATER THAN 20% (SLIGHT RISK) AND 40% (MODERATE
RISK) PROBABILITY OF EXCEEDING THE 85TH PERCENTILE OF CLIMATOLOGICAL MAXIMUM
TEMPERATURES.  LATER IN WEEK-2 AS THE RIDGE RETROGRADES WESTWARD, A SLIGHT RISK
OF MUCH ABOVE-NORMAL TEMPERATURES IS FORECAST ACROSS MUCH OF THE GREAT BASIN
AND SOUTHWEST, WHERE SIMILAR RISKS OF EXCEEDING THE 85TH PERCENTILE OF
CLIMATOLOGICAL MAXIMUM TEMPERATURES ARE INDICATED BY THE GEFS.



ACCORDING TO THE U.S. DROUGHT MONITOR (USDM), VALID ON JUNE 21, SEVERE, OR
GREATER INTENSITY, DROUGHT COVERS 4.24 PERCENT OF THE U.S. DROUGHT MONITOR
AREAS (INCLUDING ALASKA, HAWAII, AND PUERTO RICO), UP SLIGHTLY FROM 4.00
PERCENT ON JUNE 14.

FORECASTER: DANIEL HARNOS

$$



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