April Weather Discussion.

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srainhoutx
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Although we are still a ways out and folks normally have a lot of activities planned, guidance suggests that we may see some stormy weather during the Easter Weekend time frame. We shall see.

ECMWF @ 216 Hours

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GFS @ 216 Hours

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Last edited by srainhoutx on Fri Apr 30, 2010 8:01 am, edited 17 times in total.
Reason: Change The Title
Carla/Alicia/Jerry(In The Eye)/Michelle/Charley/Ivan/Dennis/Katrina/Rita/Wilma/Humberto/Ike/Harvey

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Ptarmigan
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I remember Good Friday and Easter Day night in 1992 was very stormy. The Good Friday event was a heavy rain event. There was lots of lightning, hail, and heavy rain from that storm on Easter Day.
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wxdata
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Noticed that the Euro has slowed the upper system down a bit (at least for this run.)

http://www.ecmwf.int/products/forecasts ... !chart.gif
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wxman57
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It does look like it could be a stormy Easter Sunday. We may be able to escape the storms Friday and Saturday, though. Too early to be sure about Saturday's storm potential. I'll be in Florida next week at the NHC, where it'll be just as cold as it's been here. Can't even get an above-80F day in Florida in early April!
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Overnight GFS run moves the front through next Saturday, leaving Sunday warm. 2-meter temps in the low 80s for Easter. First prediction of 80+ temps by the GFS this season.
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srainhoutx
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Those 80's temps certainly look nice on the GFS finally. Of coarse that does raise the chances that we are heading toward some active weather as well. I noticed that FWD is already mentioning the chance of severe weather from the storm system on Easter Weekend. Timing will be an issue on which model will be correct though.

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Carla/Alicia/Jerry(In The Eye)/Michelle/Charley/Ivan/Dennis/Katrina/Rita/Wilma/Humberto/Ike/Harvey

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srainhoutx
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12Z GFS continues the trend for some rather rough weather on the Saturday before Easter.

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Carla/Alicia/Jerry(In The Eye)/Michelle/Charley/Ivan/Dennis/Katrina/Rita/Wilma/Humberto/Ike/Harvey

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Interestingly guidance suggests a very stormy pattern for Easter weekend as a very deep trough forms out W and a stout ridge builds in the E. It appears that a frontal boundry will stall near E TX/W LA on Easter Sunday. HPC Morning Update also suggests things could become rather stormy in TX and the Southern Plains with this clash of airmasses.

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PRELIMINARY EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
740 AM EDT SAT MAR 27 2010

VALID 12Z WED MAR 31 2010 - 12Z SAT APR 03 2010

LATEST GUIDANCE CONTINUES THE THEME OF A VERY ACTIVE ERN PAC THRU
CNTRL NOAM PATTERN WHILE DOWNSTREAM RIDGING INTO ERN NOAM SHOULD
GRADUALLY PUSH AWAY A SLOW MOVING SYSTEM FCST TO BE NEAR THE EAST
COAST TUE-WED. WITH BOTH ERN PAC/WRN NOAM FLOW AND THE EAST COAST
SYSTEM... THE 00Z GFS IS GENERALLY NOT AS EXTREME COMPARED TO THE
CURRENT MODEL/ENSEMBLE SPREAD AS THE GFS WAS 24 HRS AGO BUT ENOUGH
QUESTION MARKS EXIST TO FAVOR LEANING AWAY FROM ITS DETAILS FOR
THE MEDIUM RANGE FCST.

STARTING FROM VERY LATE IN THE SHORT RANGE PERIOD... CONSENSUS OF
00Z MODELS AND 12Z ECMWF/CANADIAN ENSEMBLES INDICATES A PREFERENCE
TOWARD AN OVERALL ERN PAC/WRN NOAM TROF THAT IS SLIGHTLY BROADER
THAN THE 00Z GFS DURING THE FIRST HALF OF THE MEDIUM RANGE PERIOD.
AS THE TROF CROSSES THE WEST AND EJECTS INTO THE PLAINS... THE
GFS AND GEFS MEAN ARE THE FASTEST SOLNS AND THE 00Z ECMWF/UKMET
AND 12Z ECMWF ENS MEAN ARE SLOWEST. BASED ON RECENT EXPERIENCE
THE ECMWF MAY RUN THE RISK OF BEING A LITTLE TOO SLOW BUT THE
AMPLIFIED LARGE SCALE PATTERN WOULD SUGGEST THAT TIMING IN THE
SLOWER HALF OF THE SOLN ENVELOPE IS PROBABLY BEST. BEHIND THIS
SYSTEM THE GFS IS ON THE FAST EDGE OF GUIDANCE WITH UPSTREAM
ENERGY REACHING THE WEST COAST BY LATE THU NIGHT OR FRI.

WITH THE SYSTEM GRADUALLY DRIFTING AWAY FROM THE EAST COAST...
LATE IN THE SHORT RANGE PERIOD THE 00Z ECMWF TRENDED DEEPER TO THE
CANADIAN SOLN. DEEP BIASES IN THE CMC QUESTION THE DEPTH ALOFT
AND EXTREME WWD SFC POSN OF THE ECMWF/CMC AS OF EARLY DAY 3 TUE.
ON THE OTHER HAND THE GFS LEANS TO THE ERN SIDE OF THE SPREAD.
CONTINUITY/TRENDS OF GUIDANCE AS A WHOLE AND SEPARATION OF THIS
SYSTEM FROM NRN STREAM FLOW FAVOR A SOLN IN THE SLOWER HALF OF THE
ENVELOPE WITH THE 12Z ECMWF PROVIDING A MORE MODERATE
REPRESENTATION OF THIS PREFERENCE COMPARED TO THE 00Z ECMWF/CMC
EARLY IN THE PERIOD.

EARLY PRELIMS USE FOR THE FCST FOR DAYS 3-4 TUE-WED STARTS WITH A
NEARLY EVEN BLEND OF THE 00Z ECMWF/12Z ECMWF/12Z ECMWF ENSEMBLE
MEAN TO PROVIDE GREATER EMPHASIS ON 12Z ECMWF DATA FOR THE SYSTEM
NEAR THE EAST COAST AND TO REPRESENT THE PRIMARY NON-GFS
CLUSTERING FARTHER WWD. DAYS 5-7 THU-SAT ADJUST TO A SIMPLER 00Z
ECMWF/12Z ECMWF ENSEMBLE MEAN BLEND AS THE BEST WAY TO CAPTURE THE
SLOWER HALF OF THE SOLN SPREAD WITH ERN PAC TO CNTRL NOAM FLOW AND
THE SYSTEM DEPARTING FROM THE EAST COAST.

UPDATED MORNING PRELIMS FOLLOW SAME PATTERN WITH A SUBSTITUTION OF
THE 00Z ECMWF ENS MEAN FOR PRIOR 12Z EC MEAN. SOME MINOR FRONTAL
CHANGES OCCUR IN THE NRN PLAINS/UPPER MS VALLEY OTHERWISE
FEATURES/FRONTS REMAIN THE SAME.

A SIGNIFICANT COOLING IN STORE FOR WRN CONUS WITH THE DEEP WRN
TROF AND CLOSED LOW DROPING SOUTHEAST AND SWINGING THRU THEH
SOUTHWEST ALONG WITH WET CONDITIONS OVER THE PAC NORTHWEST
SHIFTING SOUTHWARD THRU CA AND EWD THRU THE ROCKIES AND INTO THE
NRN PLAINS MID-LATE WEEK. SLOW MOVING N-S FRONTAL BOUNDARY THRU
THE CENTRAL PLAINS NWD INTO THE UPPER MS VALLEY LIKELY TO BE THE
FOCUS OF SOME HVY RAINFALL AND STRONG CONVECTION FRI INTO SUNDAY
WITH A STRONG BAROCLINIC CLASH OF A COLD TROF AND SIGNIFICANT WARM
ADVECTION AHEAD OF IT THRU THE SRN PLAINS ALONG WITH GOOD INFLOW
OF GULF MOISTURE SPREADING WELL NWD OVER A PERIOD OF DAYS.

EASTWARD HVY RAIN EVENT SETTING UP DAY 3 TUES VA-NEW ENG WITH
CONSIDERABLE DRYING AND WARMING FOLLOWING AS MID LEVEL HTS RISE
AND STRONG WARM ADVECTION OCCURS FROM THE MS VALLEY EWD TO THE
EAST COAST BY THE WEEKEND. FIRST TRUE WIDESPREAD WARMING EVENT OF
THE SPRING TO OCCUR LATE WEEK INTO EASTER WEEKEND. GREATEST
TEMPERATURE ANOMALIES TO OCCUR FROM NEW ENG TO THE GREAT LAKES
REGION WHERE H850 TEMP ANOMALIES ARE IN THE RANGE OF THREE
STANDARD DEVIATIONS ABOVE NORMAL YIELDING A LARGE AREA OF TEMPS IN
THE 60-70S OVER THIS AREA WITH UPPER 70S-LOW 80S COMMON SOUTHWARD
FROM THE NORTHEAST TO OH VALLEY AND SOUTH TO THE GULF COAST.

RAUSCH/ROSENSTEIN
Carla/Alicia/Jerry(In The Eye)/Michelle/Charley/Ivan/Dennis/Katrina/Rita/Wilma/Humberto/Ike/Harvey

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wxdata
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0z ECMWF still hints at a stalling front somewhere over SE TX.
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12z GFS has added a new wrinkle for Easter (deja vu of last year!)
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