LONGRANGE: Extended Forecast Discussion
 

FXUS02 KWBC 121807
PMDEPD

EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
207 PM EDT TUE JUL 12 2011

VALID 12Z FRI JUL 15 2011 - 12Z TUE JUL 19 2011

....HEAT WAVE TO EXPAND NORTHWARD AND WESTWARD FROM TEXAS...
....HEAVY RAIN POSSIBLE ALONG THE SOUTHEAST COAST...

MODELS ARE QUITE CONSISTENT AND RECENTLY IN GOOD AGREEMENT IN
DEVELOPING A WEST COAST TROUGH...AN EXPANDING WARM CORE RIDGE
ACROSS THE PLAINS...AND A WESTERN ATLANTIC/EASTERN CANADA MEAN
TROUGH DURING THE MEDIUM RANGE PERIOD. THE SIZE AND STRENGTH OF
THE HIGH (595 DM 500 MB HEIGHTS AT THE CORE) COMBINED WITH GOOD
MODEL AGREEMENT PROVIDE A SMALL ARRAY OF ACCEPTABLE AND NEARLY
EQUAL MODEL BLENDS TO SMOOTH SMALL-SCALE OR DETAIL DIFFERENCES
THROUGH THE PERIOD. THUS...USED A 00Z GFS/00Z ECMWF/00Z UKMET
COMPROMISE FOR THE PRESSURES/FRONTS THROUGH SUNDAY BEFORE
SWITCHING TO A 00Z ECMWF/00Z GFS COMPROMISE EARLY NEXT WEEK.

THE STRENGTHENING WARM CORE RIDGE ACROSS THE SOUTHERN PLAINS
SHOULD LEAD TO HIGH TEMPERATURES BETWEEN 100 AND 110 DEGREES NEAR
ITS CORE MIGRATING NORTHWARD AND WESTWARD THROUGH THE PERIOD...
WITH LOCALLY HIGHER VALUES POSSIBLE. ANY RECORD HIGHS SET DURING
THE SUMMER OF 1980 SHOULD CONTINUE TO BE THREATENED DURING THE
MEDIUM RANGE PERIOD. WHILE THUNDERSTORM ACTIVITY ACROSS NORTHERN
TEXAS/OKLAHOMA/KANSAS SHOULD BE HARD TO COME BY...DISTURBANCES
EMBEDDED WITHIN THE INCREASINGLY DEEP EASTERLY FLOW UNDER THE BASE
OF THE RIDGE COULD LEAD TO THUNDERSTORMS ACROSS THE
SOUTHEAST/FLORIDA/SOUTHERN TEXAS FROM THIS WEEKEND INTO EARLY NEXT
WEEK. OF PARTICULAR NOTE IS A SMALL BUT POTENTIALLY SIGNIFICANT
AREA OF LOW PRESSURE WHICH THE MODELS ARE DEVELOPING ALONG A
STATIONARY FRONT DRAPED ACROSS THE SOUTHEAST COAST SUNDAY THROUGH
TUESDAY. DESPITE RELATIVELY WEAK MSLP VALUES...ITS SLOW MOVEMENT
WITHIN AN ANOMALOUSLY MOIST ENVIRONMENT SUPPORTS THE
POSSIBILITY...
ALBEIT WITH LIMITED PREDICTABILITY...OF HEAVY RAINFALL DEVELOPING
ALONG PORTIONS OF THE SOUTHEAST COAST DURING THE SECOND HALF OF
THE PERIOD. WILL NEED TO MONITOR FOR FURTHER MODEL CONTINUITY
AND/OR POTENTIALLY STRONGER SCENARIOS FOR INCREASING CONFIDENCE.
FOR NOW WILL DEPICT A WEAK LOW NEAR THE GA/SC COAST PER
COORDINATION WITH THE NHC AND SLIGHTLY INCREASE THE DAY 4/5 QPF
TOTALS. OTHERWISE... AFTERNOON AND EVENING MONSOON-RELATED
THUNDERSTORMS ARE EXPECTED FROM THE SOUTHWEST INTO THE CENTRAL
ROCKIES WEST OF THE RIDGE...WHILE ANY THUNDERSTORM COMPLEXES THAT
FORM ALONG THE NORTHERN PERIPHERY OF THE RIDGE SHOULD MOVE FROM
THE NORTHERN PLAINS THROUGH SOUTHEAST CANADA/THE GREAT
LAKES...BEFORE POSSIBLY DROPPING INTO THE MID-ATLANTIC AND
NORTHEASTERN STATES THEREAFTER.

ROTH/JAMES
$$

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