Prognostic Meteorological Discussion
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FXUS02 KWBC 291559
PMDEPD

EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1158 AM EDT WED MAR 29 2017

VALID 12Z SAT APR 1 2017 - 12Z WED APR 5 2017

***OVERVIEW AND GUIDANCE EVALUATION PLUS PREFERENCES***

THE SPLIT FLOW PATTERN ACROSS THE CONTINENTAL U.S. AND CANADA IS
EXPECTED TO CONTINUE THROUGH EARLY NEXT WEEK, WITH A PROGRESSIVE
NORTHERN STREAM AND A SERIES OF UPPER LOWS TRACKING EASTWARD IN
THE SOUTHERN STREAM.  THE CLOSED LOW TRACKING EASTWARD FROM THE
ROCKIES ON SUNDAY IS SHOWING SIMILARITIES COMPARED TO THE STORM
SYSTEM CURRENTLY AFFECTING THE SOUTH-CENTRAL U.S., WITH THE
EXCEPTION THAT THIS NEW ONE WILL LIKELY TAKE A TRACK FARTHER TO
THE SOUTH CLOSER TO THE GULF COAST.  BY THE END OF THE FORECAST
PERIOD, MOST OF THE MODEL GUIDANCE IS INDICATING A GRADUAL
EASTWARD TRANSITION OF THE OVERALL PATTERN AS A DEEPENING SYNOPTIC
SCALE TROUGH SETTLES OVER THE NORTHEASTERN PACIFIC AND AN UPPER
RIDGE BEGINS BUILDING DOWNSTREAM ACROSS THE WESTERN HALF OF THE
NATION.

IN RECENT DAYS, THE MODEL GUIDANCE HAS DIFFERED SIGNIFICANTLY WITH
THE PROGRESSION AND TRACK OF AN UPPER LOW FORECAST TO MOVE OUT OF
THE SOUTHERN ROCKIES FROM SATURDAY ONWARD ALONG WITH SPECIFICS OF
INCOMING PACIFIC ENERGY.  THE AMOUNT OF MODEL SPREAD HAS NOW
DECREASED WITH TODAY`S FORECAST, WITH THE OPERATIONAL 00Z ECMWF
MORE IN LINE WITH THE MODEL CONSENSUS, ESPECIALLY WITH THE
EVOLUTION OF THE SECOND UPPER LEVEL TROUGH OVER THE ROCKIES DURING
THE SECOND HALF OF THE PERIOD.  THE CMC APPEARED TO BE MORE
AMPLIFIED THAN THE MODEL CONSENSUS WITH THE SOUTHWEST U.S. TROUGH
ON TUESDAY.  TAKEN AS A WHOLE THE PLAUSIBILITY OF VARIOUS
SOLUTIONS SEEMS TO HAVE BECOME A LITTLE MORE BALANCED THAN
APPEARED TO BE THE CASE PREVIOUSLY.  THEREFORE THE UPDATED
FORECAST ADJUSTED TO A NEARLY EVEN BLEND AMONG THE GFS, ECMWF, AND
WPC CONTINUITY, WITH MORE OPERATIONAL WEIGHTING EARLY-MID PERIOD
AND MORE ENSEMBLE MEAN WEIGHTING LATE.


***SENSIBLE WEATHER HIGHLIGHTS AND POTENTIAL HAZARDS***

THE PART OF THE U.S WITH THE GREATEST WEATHER IMPACTS DURING THIS
TIME SHOULD ONCE AGAIN BE TEXAS AND EXTENDING EASTWARD TO THE DEEP
SOUTH.  THE UPPER LEVEL LOW AND THE RESULTING OCCLUDED SURFACE LOW
ARE FORECAST TO TRACK SLOWLY EASTWARD AND PRODUCE MULTIPLE ROUNDS
OF BAD WEATHER.  THE STORM PREDICTION CENTER IS INDICATING
FAVORABLE CONDITIONS FOR ADDITIONAL SEVERE WEATHER OVER THE
UPCOMING WEEKEND ACROSS PARTS OF TEXAS AND TOWARDS THE CENTRAL
GULF COAST.  VERY HEAVY RAINFALL CAPABLE OF PRODUCING FLASH
FLOODING WILL BE ALSO BE POSSIBLE AHEAD OF THE LOW ACROSS SOUTHERN
TEXAS AND LOUISIANA.  SOME LOCATIONS FROM SOUTHEAST TEXAS TO THE
FLORIDA PANHANDLE COULD RECEIVE IN EXCESS OF 5 INCHES OF RAIN AS
DEEP MOISTURE FROM THE GULF OF MEXICO IS ADVECTED INTO THIS STORM
SYSTEM.  FUTURE EXCESSIVE RAINFALL OUTLOOKS WILL HAVE ADDITIONAL
INFORMATION ON THE FLOODING POTENTIAL AS THE EVENT DRAWS CLOSER.

EXPECT TEMPERATURES TO BE ABOVE NORMAL ACROSS THE MAJORITY OF THE
NATION DURING THIS TIME PERIOD, WITH SOME OF THE GREATEST
ANOMALIES EXPECTED FROM MONTANA TO THE UPPER MIDWEST.  ANOTHER
AREA WITH NOTEWORTHY WARM TEMPERATURES WILL BE FROM SOUTHERN TEXAS
TO THE SOUTHEAST U.S., WITH WIDESPREAD HIGHS IN THE 80S LIKELY AND
NOTICEABLE LEVELS OF HUMIDITY, AND MILD OVERNIGHT LOWS.  COLDER
THAN NORMAL READINGS ARE LIKELY NEAR THE SOUTHWESTERN UPPER LOW
THAT TRACKS TOWARDS THE SOUTHERN PLAINS OVER THE WEEKEND, AND ALSO
FOR THE NORTHEAST U.S. AT THE BEGINNING OF THE PERIOD.

Hamrick

$$





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