Skip Navigation Links weather.gov 
NOAA logo - Click to go to the NOAA homepage National Weather Service   NWS logo - Click to go to the NWS homepage
The Weather Prediction Center

 
 

 

Follow the Weather Prediction Center on Facebook Follow the Weather Prediction Center on Twitter
NCEP Quarterly Newsletter
WPC Home
Analyses and Forecasts
   National High & Low
   WPC Discussions
   Surface Analysis
   Days ½-2½ CONUS
   Days 3-7 CONUS
   Days 4-8 Alaska
   QPF
   PQPF
   Flood Outlook
   Winter Weather
   Storm Summaries
   Heat Index
   Air Quality
   Tropical Products
   Daily Weather Map
   GIS Products
Current Watches/
Warnings

Satellite and Radar Imagery
   Satellite Images
   National Radar
Product Archive
WPC Verification
   QPF
   Medium Range
   Model Diagnostics
   Event Reviews
International Desks
Development and Training
   Development
WPC Overview
   About the WPC
   Staff
   WPC History
   Accomplishments
   Other Sites
   FAQs
Meteorological Calculators
Contact Us
   About Our Site
 
USA.gov is the U.S. Government's official web portal to all federal, state, and local government web resources and services.
 
Extended Forecast Discussion
 
(Caution: Version displayed is not the latest version. - Issued 0658Z Aug 20, 2014)
 
Version Selection
Versions back from latest:  0   1   2   3   4   5   6   7   8   9   10   
 
Abbreviations and acronyms used in this product
 
Geographic Boundaries -  Map 1: Color  Black/White       Map 2: Color  Black/White


EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
258 AM EDT WED AUG 20 2014

VALID 12Z SAT AUG 23 2014 - 12Z WED AUG 27 2014

.OVERVIEW...
THE MEDIUM RANGE FORECAST PERIOD FOCUSES ON A
PROGRESSIVE...LOW-AMPLITUDE FLOW PATTERN ALOFT MIGRATING SEVERAL
UPPER-LEVEL SYSTEMS THROUGH SOUTHERN CANADA AND THE NORTHERN TIER.
ACROSS THE SOUTHEAST...SOUTHERN PLAINS AND NORTHERN GULF OF
MEXICO...A BROAD SUBTROPICAL RIDGE AXIS PREVAILS ALONG 25N-30N
LATITUDE---ANCHORING HOT AND HUMID CONDITIONS OVER A LARGE PORTION
OF THE REGION THROUGH THE MEDIUM RANGE PERIOD.  

.MODEL PREFERENCES/UNCERTAINTY ASSESSMENT...
THE 19/12Z ECENS/NAEFS CAPTURE THE GENERAL LOWER-AMPLITUDE WAVE
STRUCTURE  AND PROGRESSIVE FLOW ACROSS SOUTHERN CANADA. AND FOR
THE MOST PART...NOW IDENTIFY WITH THE THERMAL PATTERN ANTICIPATED
BENEATH THE MID-LEVEL RIDGE--AND ISOLATED POCKETS OF TRIPLE-DIGIT
READING IN THE OZARKS...OKLAHOMA AND TEXAS. 

USING THE DETERMINISTIC GUIDANCE AND PINPOINTING THE MOST ACTIVE
WEATHER THIS MEDIUM RANGE PERIOD...THE 19/12Z GFS/ECMWF WERE IN
DECENT AGREEMENT THROUGH DAY 4 WITH SIGNIFICANT HEIGHT FALLS
ACROSS THE NORTHERN ROCKIES AND NORTHERN PLAINS PUSHING OUT ACROSS
THE NORTH CENTRAL PLAINS--SOUTH DAKOTA AND NEBRASKA--ON SUNDAY
MORNING. AHEAD OF THE COLD FRONT...A BROAD AREA OF 250MB-500MB
LAYER DIVERGENCE FANS OUT ACROSS THE HIGH PLAINS OF WYOMING AND
COLORADO...WITH THE 19/12Z ECMWF A SLIGHTLY FASTER/STRONGER
SOLUTION VS THE 19/12Z GFS WITH RESPECT TO SOUTHWESTERLY JET
ENERGY AND 500MB PVA STREAKING OUT OF THE CENTRAL DIVIDE AND
MIGRATING ACROSS THE UPPER- AND MID-MISSOURI VALLEY ON SUNDAY
AFTERNOON/EVENING. BY MONDAY MORNING...THIS JET STREAK AND THE
CONVECTION ASSOCIATED WITH IT SPINS UP A RATHER ENERGETIC SURFACE
CYCLONE INVOF WEST CENTRAL MINNESOTA WITH LOW-LEVEL COLD ADVECTION
SURGING EAST-SOUTHWARD INTO THE CENTRAL PLAINS. ON MONDAY...THE
TEMPERATURE CONTRASTS AHEAD AND BEHIND THE FRONT WILL BE CLOSE TO
30F...WITH MUGGY CONDITIONS IN THE LOWER THIRD OF THE MISSOURI
VALLEY ADVECTING--IN A MODIFIED AIRMASS--NORTHEASTWARD AHEAD OF
THE FRONT AND INTO THE CENTRAL GREAT LAKES. THIS CLASH OF
CONTRASTING AIRMASSES--ALONG THE FRONT--IS ANTICIPATED TO BE AN
ACTIVE WEATHER SCENARIO ACROSS THE UPPER MIDWEST/MISSISSIPPI
VALLEY FOR DAY 5...AS THE UPPER-LEVEL FLOW BEHIND THE COLD FRONT
SHIFTS TO MORE OF A WESTERLY COMPONENT AND SHEARS THE COLD FRONT
EASTWARD ACROSS THE OHIO VALLEY.

.SENSIBLE WEATHER HIGHLIGHTS...
VERY WARM AND HUMID CONDITIONS EXPECTED FOR THE SOUTH BENEATH THE
WESTERN ATLANTIC RIDGE---EXPANDING WEST AND WEST-NORTHWEST INTO
THE SOUTH PLAINS AND MID-MISSISSIPPI VALLEY THIS WEEKEND.

A BACKDOOR COLD FRONT IS ASSOCIATED WITH A WEAK TROUGHING IN THE
WESTERN ATLANTIC WILL PRODUCE HIGH PRESSURE AND AN EASTERLY FLOW
ALONG THE EAST COAST...SURGING SOUTHWARD INTO THE
PIEDMONT...COASTAL GEORGIA AND THE 'FIRST COAST' AND 'SPACE COAST'
OF FLORIDA. THE FRONT DOES WEAKEN EARLY NEXT WEEK...BECOMES A
STATIONARY FRONT AND A FOCUS FOR SHOWERS AND THUNDERSTORMS ACROSS
THE PENINSULA FOR NEXT TUESDAY AND WEDNESDAY.

VOJTESAK