Prognostic Meteorological Discussion
Issued by NWS

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FXUS21 KWNC 111933
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT JULY 11 2014

SYNOPSIS: A STRONG COLD FRONT IS EXPECTED TO MOVE FROM THE GREAT LAKES TO THE
EAST COAST AT THE BEGINNING OF THIS PERIOD.  BEHIND THE FRONT, COOL HIGH
PRESSURE IS FORECAST TO BRING BELOW NORMAL TEMPERATURES TO MOST OF THE EASTERN
HALF OF THE LOWER 48.  IN THE INTERMOUNTAIN WEST, HIGH PRESSURE IS FORECAST TO
PREVAIL, FAVORING WARMER TEMPERATURES.

HAZARDS

MUCH ABOVE-NORMAL TEMPERATURES FOR PARTS OF THE GREAT BASIN AND NORTHERN
INTERMOUNTAIN WEST, MON-FRI, JUL 14-18.

HIGH WINDS FOR NORTHWEST ALASKA, TUE-WED, JUL 15-16.

HEAVY RAIN FOR NORTHWEST ALASKA, WED, JUL 16.

HIGH WINDS FOR THE ALEUTIANS AND SOUTHWESTERN COAST OF ALASKA, WED-THU, JUL
16-17.

SEVERE WEATHER FOR PARTS OF THE MISSISSIPPI AND OHIO VALLEYS AND THE
MID-ATLANTIC, MON, JUL 14.

HEAVY RAIN FOR PARTS OF THE SOUTHERN ROCKIES, OHIO AND TENNESSEE VALLEYS AND
THE NORTHEAST, MON-TUE, JUL 14-15.

HEAVY RAIN FOR COASTAL PORTIONS OF THE CAROLINAS AND SOUTHERN PLAINS, WED-THU,
JUL 16-17.

FLOODING OCCURRING OR IMMINENT FOR PARTS OF NORTH DAKOTA AND THE MIDDLE
MISSISSIPPI VALLEY.

SEVERE DROUGHT FOR PARTS OF THE GREAT PLAINS, SOUTHWEST, PACIFIC NORTHWEST,
GREAT BASIN, AND CALIFORNIA.

DETAILED SUMMARY

FOR MONDAY JULY 14 - FRIDAY JULY 18: THE FIRST PART OF THIS FORECAST PERIOD IS
EXPECTED TO FEATURE AN AMPLIFIED UPPER-LEVEL TROUGH ACROSS THE GREAT LAKES
REGION.  AS THIS TROUGH AMPLIFIES, A SURFACE COLD FRONT IS PREDICTED TO MOVE
FROM THE UPPER MIDWEST TO THE SOUTHEAST.  AS IT MAKES ITS WAY TOWARDS THE EAST
COAST, WARM, MOIST AIR IN ADVANCE OF THE FRONT COUPLED WITH AN UPPER-LEVEL JET
STREAK IS EXPECTED TO SET THE STAGE FOR A SEVERE WEATHER OUTBREAK FROM EASTERN
PENNSYLVANIA TO NORTHEAST ARKANSAS.  HOWEVER, BASED UPON WHERE THE GREATEST
AMOUNTS OF ATMOSPHERIC MOISTURE ARE EXPECTED TO BE, THE GREATEST CHANCES FOR
HEAVY RAIN INCLUDE THE TENNESSEE VALLEY AND NEW ENGLAND ON MONDAY AND TUESDAY,
THE 14TH AND 15TH.  BECAUSE THE COLD FRONT IS FORECAST TO LINGER ALONG THE
COASTAL CAROLINA REGION, THIS PART OF THE COUNTRY IS EXPECTED TO RECEIVE HEAVY
RAIN FROM MONDAY THE 14TH THROUGH THURSDAY THE 17TH.



THE COLD FRONT IS FORECAST TO STRETCH FROM THE EAST COAST BACK TO THE ROCKIES
AS HIGH PRESSURE IS EXPECTED TO BE SITUATED OVER THE NORTHERN AND CENTRAL
PLAINS.  THE COMBINATION OF UPSLOPE FLOW AND THE FOCUS OF PRECIPITATION
ASSOCIATED WITH THE FRONT, HEAVY RAIN IS ANTICIPATED FOR PARTS OF THE SOUTHERN
ROCKIES.  WITH RAINFALL TOTALS OF MORE THAN 2 INCHES PREDICTED OVER HIGH
TERRAIN, LOCALIZED FLASH FLOODING IS POSSIBLE AS WELL.



IN ADDITION, AN UPPER-LEVEL RIDGE IS FORECAST TO AMPLIFY IN THE WESTERN STATES,
FAVORING MUCH ABOVE NORMAL TEMPERATURES IN PARTS OF THE PACIFIC AND
INTERMOUNTAIN WEST, WITH DAILY MAXIMUM TEMPERATURES 12 TO 20 DEGREES ABOVE
NORMAL POSSIBLE THROUGHOUT THIS ENTIRE FORECAST PERIOD.



AN UPPER-LEVEL SHORTWAVE CURRENTLY IN THE EASTERN PACIFIC IS FORECAST TO ROTATE
AROUND THE WESTERN RIDGE AXIS AND MOVE INTO THE SOUTHERN PLAINS.  THE
DIVERGENCE ASSOCIATED WITH THIS SHORTWAVE, COMBINED WITH NORTHWEST FLOW, MAKES
CONDITIONS FAVORABLE FOR THE FORMATION OF A MESOSCALE CONVECTIVE SYSTEM.  THUS,
A HEAVY RAIN HAZARD IS INDICATED ON THE MAP FOR PARTS OF OKLAHOMA AND TEXAS ON
THE 16TH AND 17TH, WITH SEVERE WEATHER ALSO POSSIBLE.



IN ALASKA, A LARGE CLOSED UPPER-LEVEL LOW SLOWLY ROTATING NEAR THE ALEUTIANS IS
EXPECTED TO BE THE IMPETUS FOR UNSETTLED WEATHER.   TOWARDS THE END OF THIS
PERIOD, THE LOW IS FORECAST TO OPEN UP AND MOVE INTO THE STATE.  THE ASSOCIATED
SURFACE LOW IS PREDICTED TO MOVE PARALLEL TO THE ALEUTIANS AND BRING HIGH WINDS
OF 30-40 KNOTS TO THE ISLANDS AS WELL AS THE SOUTHWESTERN COAST.  IN ADDITION,
A SEPARATE UPPER-LEVEL SHORTWAVE IS FORECAST TO MOVE EAST FROM NORTHERN RUSSIA.
 IT IS EXPECTED TO BRING HIGH WINDS OF AT LEAST 30 KNOTS TO THE NORTH SLOPE
FROM THE 15TH TO THE 16TH.  HEAVY RAIN IS ALSO POSSIBLE WITH TOTALS OF 1 INCH
OR MORE ON THE 16TH.  BECAUSE THIS PART OF THE STATE IS VERY DRY THIS TIME OF
YEAR, SIGNIFICANT IMPACTS FROM THIS STORM COULD OCCUR.  SOME MODELS ARE
FORECASTING THAT THE SHORTWAVE IMPACTING THE NORTH SLOPE WILL PHASE WITH THE
LARGE LOW SOUTH OF THE ALEUTIANS.  IF THIS WERE TO HAPPEN, IT WOULD INCREASE
THE CHANCES OF HIGH WINDS AND HEAVY RAIN FOR THE ENTIRE WESTERN COAST,
ALEUTIANS AND SOUTHERN COAST.



FLOODING IN THE MID-MISSISSIPPI VALLEY AND NORTH DAKOTA IS PREDICTED TO
CONTINUE DURING THIS FORECAST PERIOD, AS WATER FROM RECENT RAINFALLS OF 3-8
INCHES (AND UP TO 19 INCHES DURING THE MONTH OF JUNE) CONTINUES TO FLOW INTO
THE LARGE RIVERS.

FOR SATURDAY JULY 19 - FRIDAY JULY 25: THE LATEST NUMERICAL MODELS ARE ONCE
AGAIN INDICATING THAT THE UPPER-LEVEL RIDGE IN THE WEST WILL DEAMPLIFY AND THE
FLOW WILL BECOME MORE ZONAL.  THIS WILL RETURN TEMPERATURES BACK TO NEAR NORMAL
VALUES AND END THE MUCH ABOVE NORMAL TEMPERATURE HAZARD.



BASED ON THE LATEST DROUGHT MONITOR VALID ON JULY 8, THE COVERAGE OF SEVERE TO
EXCEPTIONAL DROUGHT ACROSS THE CONTINENTAL U.S. REMAINED NEARLY STEADY AT JUST
UNDER 25 PERCENT.

FORECASTER: KENNETH PELMAN

$$



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