January Weather Discussion: Slight Chance Severe Storms

[srainhoutx]

CPC:

8-14 DAY OUTLOOK FOR JAN 04 - 10 2011

DURING WEEK 2 THE ENSEMBLE MEAN SOLUTIONS INDICATE A SLIGHT PROGRESSION OF THE
LONGWAVE PATTERN ACROSS THE LOWER 48 AS A TROUGH SLOWLY LIFTS OUT OF THE
SOUTHWESTERN CONUS AND SHIFTS INTO THE WEST-CENTRAL CONUS. THE 0Z GFS ENSEMBLE
MEAN INDICATES THAT THE NORTH ATLANTIC OSCILLATION (NAO) INDEX WILL BECOME
HIGHLY NEGATIVE BY THE BEGINNING OF THE WEEK 2 PERIOD. THE NEGATIVE NAO INDEX
IS CONSISTENT WITH MODEL GUIDANCE DEPICTING A LARGE POSITIVE 500-HPA HEIGHT
ANOMALY CENTER OVER THE DAVIS STRAIT AND SOUTHERN GREENLAND.
THE OFFICIAL BLEND 500-HPA HEIGHT CHART INDICATES BELOW NORMAL HEIGHTS ACROSS MOST OF THE LOWER 48
AND NEAR AVERAGE HEIGHTS ACROSS ALASKA.

PERSISTENT, BELOW NORMAL 500-HPA HEIGHTS ARE EXPECTED TO ENHANCE THE ODDS FOR
BELOW NORMAL TEMPERATURES IN THE SOUTHWESTERN CONUS. LOWER 500-HPA HEIGHTS
COMPARED TO DAYS 6-10 AND A NEGATIVE NAO INDEX FAVOR NEAR OR BELOW NORMAL
TEMPERATURES ACROSS MOST THE EASTERN CONUS. DUE TO VARYING SIGNALS FROM THE
PRECIPITATION TOOLS, THE PRECIPITATION OUTLOOK IS A LOW CONFIDENCE FORECAST. AN
UPPER-LEVEL TROUGH IS EXPECTED TO INCREASE THE CHANCES FOR ABOVE MEDIAN
PRECIPITATION ACROSS THE NORTHERN AND CENTRAL ROCKIES. DOWNSTREAM OF THE
UPPER-LEVEL TROUGH, ENHANCED ODDS FOR ABOVE MEDIAN PRECIPITATION ARE FORECAST
IN THE SOUTHEASTERN CONUS. NEAR OR BELOW MEDIAN PRECIPITATION IS FAVORED ALONG
THE WEST COAST.

A MORE ZONAL FLOW PATTERN IS EXPECTED TO PREVAIL ACROSS ALASKA WHERE NEAR
NORMAL TEMPERATURES ARE FAVORED ACROSS MUCH OF THE STATE. INCREASED CHANCES FOR
ABOVE MEDIAN PRECIPITATION ARE FORECAST ACROSS NORTHERN AND EASTERN ALASKA
ALONG WITH THE ALASKAN PANHANDLE.

[tireman4]

Interesting. Below normal temperatures. Humm.

[srainhoutx]

Interesting pattern ahead...

[sleetstorm]

In english please, srainhoutx. Also, how is this month, year, and decade looking to end weathrewise, warm, cool, or cold and wet or dry?

[srainhoutx]

Sorry, I was in a hurry and rather busy this morning. The models (Euro and GFS) suggest a return of another big blocking pattern near Greenland and a bit better cooperative Pacific pattern. Overall it suggests a return to a colder, stormier pattern E of the Rockies and just perhaps if the Pacific cooperates, a better chance of moisture for our area. There are suggestions of an SSW (Sudden Stratospheric Warming) event as well near the first week of January which suggests lower heights near the Polar Regions and colder air being forced to the surface. We've been looking for a pattern change and that trend continues since the Christmas Eve storm. Enjoy the rainfall this week in relation to these changes. It's been a long time coming.

[sleetstorm]

Okay, thank you, srainhoutx.

[srainhoutx]

Some interesting changes are occurring regarding January. We have seen a strongly -AO, -NAO and -PNA regime since November. The signals are suggesting that after a brief rise in the AO index, a plunge will again occur. What is interesting is the PNA is now suggesting a more positive solution suggesting that the pattern that started with the New Years Eve storm will continue and after a brief period of warmer temps, we may well start to swing back to and period of a rollercoaster pattern as the Pacific becomes more cooperative. Those that have been thinking a warming trend and drier pattern is ahead that is typical in a La Nina pattern may have to revisit that idea and adjust their forecast.


AO



PNA



NAO

[srainhoutx]

The GFS has it has well...

[srainhoutx]

HGX suggesting we will be under cloud cover after the front...until the end of next week...hmmm...

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
407 PM CST WED DEC 29 2010

.DISCUSSION...
WIDESPREAD CONVECTION OVER THE SRN HALF OF THE AREA LOOKS TO HAVE
KEPT THINGS QUIET OVER THE NRN HALF TODAY. WILL KEEP WITH HIGHISH
POPS FOR THESE LOCATIONS FOR THE EARLY PART OF THE EVENING BEFORE
TAPERING THINGS OFF AREAWIDE FROM THE WEST. IN THE WAKE OF ALL OF
THIS ACTIVITY WE COULD SEE THE DEVELOPMENT OF SOME SEA FOG ACROSS
THE BAYS/COASTAL WATERWAYS TONIGHT AS THE ONSHORE FETCH PERSISTS.
RELUCTANT TO DROP POPS A WHOLE LOT FOR TOMORROW GIVEN THE LINGER-
ING SWLY FLOW ALOFT AND THE PROXIMITY OF THE WRAM FRONT JUST OFF-
SHORE (MOVING BACK INLAND). POPS GO UP AGAIN ON FRI WITH THE COLD
FRONTAL PASSAGE. DECENT WAA IN ITS WAKE BUT IT SHOULD FEEL COOLER
WITH THE MID/HIGH OVERRUNNING CLOUDS (VIA SW FLOW ALOFT) PERSIST-
ING THROUGH THE WEEKEND IT WOULD SEEM. THIS OVERALL UPPER PATTERN
OF DEVELOPING LOW/TROF AROUND SRN CALI/CALI BAJA SHOULD TRANSLATE
TO A PERSISTENT TAP OF PACIFIC MOISTURE AND LINGERING MID TO HIGH
CLOUDS OVER THE STATE UNTIL/THROUGH THE PASSAGE OF THIS MAIN TROF
ITSELF. AND EXTENDED PROGS CURRENTLY INDICATING THAT THIS MAY NOT
HAPPEN UNTIL THE END OF NEXT WEEK...AT THE EARLIEST... STAY TUNED.41

[sleetstorm]

Translation, please, srainhoutx?

[wxman57]

Latest GFS says warm/mild and very wet beyond next Monday. Euro is in general agreement.

[srainhoutx]

What a change ahead via guidance. After months of no rain and a persistant NW flow, we have switched to a W and SW influence and cooperative Pacific flow. While the temps may not be all that cold, the switch to a wetter pattern is certainly a change...

PRELIMINARY EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
737 AM EST THU DEC 30 2010

VALID 12Z MON JAN 03 2011 - 12Z THU JAN 06 2011

...WET CONDITIONS EXPECTED ACROSS THE GULF COAST...

A POSITIVELY TILTED TROUGH REMAINS ACROSS NORTH AMERICA THIS
PERIOD...STRETCHING FROM HUDSON BAY/EASTERN CANADA INTO THE
SOUTHWEST...WITH THE SOUTHWESTERN PORTION ANCHORED IN PLACE BY
RIDGING IN/NEAR WESTERN CANADA. OUTSIDE THE 00Z UKMET...THE
REMAINDER OF THE GUIDANCE SHOWS THIS EVOLVING IDEA AND IS IN
REASONABLE AGREEMENT. THE 00Z GFS AND 00Z ECMWF SHOW MINIMAL
SPREAD ACROSS THE MAP...AND ARE INDEPENDENTLY SUPPORTED BY THEIR
ENSEMBLE MEAN SOLUTIONS...SO USED A COMPROMISE OF THE 00Z GFS/00Z
ECMWF THROUGH THE PERIOD TO DEAL WITH UNCERTAINTY. CONFIDENCE IS
HIGHEST IN THIS PATTERN ACROSS THE SOUTHWEST/NORTHWESTERN GULF
COAST...AND LOWEST ACROSS THE NORTHEAST AND GREAT LAKES DUE TO
DIFFERENCES IN THE GUIDANCE ON WHETHER OR NOT A NEW GYRE ACROSS
ATLANTIC CANADA WILL BECOME DOMINANT OVER THE HUDSON BAY SYSTEM.
AROUND THE BACKSIDE OF THE VORTEX...AN ARCTIC FRONT IS EXPECTED TO
WAVER ACROSS THE NORTHERN PLAINS. THE PATTERN OVER THE NEXT WEEK
LOOKS UNCHARACTERISTICALLY WET FOR A LA NINA/COLD ENSO EPISODE
ACROSS THE GULF COAST DUE TO THE PERSISTENCE OF THIS FLOW REGIME.

...UPDATED PRELIMS AGAIN USED ECMWF AND ECMWF AS A BASE WITH BOTH
CLOSER TO ENS MEANS OF GFS AND ECMWF AND CMC OPERATIONAL MID WEEK.


CLOSED MID LEVEL LOW DROPPING SLOWLY SWD JUST OFFSHORE OF THE CA
COAST WILL BRING MORE RAINS INTO CENTRAL AND SOCAL THIS PERIOD.
THE FIRST DOWN THE CENTRAL COASTAL RANGES SUNDAY THEN DROPPING
DOWN ALONG THE SOCAL COASTAL RANGES MONDAY. THE NEXT SYSTEM HAS
LIGHTER MODEL OUPUT BUT ADDITIONAL RAINS TUES INTO WEDNESDAY
POTENTIALLY HEAVIER OVER COASTAL SOCAL AND NRN BAJA BY MID WEEK.

PARALLEL TO THE COAST MID TO UPPER LEVEL FLOW FROM THE SRN STEAM
WILL PERSIST ALONG THE GULF COASTAL REGION WITH H850 INFLOW
POOLING HIGHER PW VALUES ALONG A DEVELOPING AND THEN PERSISTING
STATIONARY FRONTAL BOUNDARY. EXPECT SHOWERS AND OVERRUNNING
RAINFALL TO DEVELOP ALONG AND JUST OFFSHORE OF THE GULF COAST FROM
NE TX TO THE FL PANHANDLE WED INTO THE WEEKEND .

MID LEVEL BLOCKING AND A LARGE STRONG POSITIVE HT ANOMALY RETURNS
TO NRN CANADA WITH A DEEP VORTEX LOCKING IN OVER ONTARIO AS PER
8-10 DAY ECMWF. STRONG SRN STREAM MID LEVEL TROF WILL SWING THRU
SRN TX INDUCING LOW PRESSURE ALONG THE GULF COAST IN A MOISTURE
RICH ENVIRONMENT AND BRING AN AREA OF LOW PRESSURE INTO THE
SOUTHEAST AND UP ALONG THE SOUTHEAST AND MID ATLC SEABOARD OVER
THE NEXT WEEKEND. LONGER RANGE CMC AND ECMWF SUPPORT THIS
SCENARIO.
ROTH/ROSENSTEIN

[redneckweather]

Wet is good. I actually think that the entire month of January will be on the mild/warm side and that could roll into February. I believe we have seen the coldest weather of our fall/winter season already during November and December. As we discussed back in October I believe, this is how things would turn out for us here in Southeast, Texas.

[srainhoutx]

Could be, redneckweather. I'd still be cautious though as there are signals of a return to a strong blocking regime as well as a SSW/MWW (Sudden Stratospheric Warming/Mid Winter Warming) event in the upper levels. Also the Euro suggests a splitting of the Polar Vortex and dropping that feature into Siberia breaking down the persistent Kamchatka ridging which suggests some mighty cold air could be dislodged and spread across the Polar region. I suspect after a brief vacation for the colder temps, we may well see a return of truly Arctic air spilling S into the Lower 48. My hunch is winter is far from over, IMO. Regardless, we have a pattern change and that is a good thing for our drought parched region.

[BiggieSmalls]

This is shaping up to be one of the lamest "winters" in recent history. I'll be surprised if even DFW gets snow at this point.

[Andrew]

18z GFS doesn't show much in the way of rain tom but as we have been seeing from the past couple of runs the days after might be a different story

http://www.nco.ncep.noaa.gov/pmb/nwprod ... loop.shtml


You can see from the loop above that the flow is going to come from the pacific and is going to send disturbances our way. The GFS paints a wet picture for a lot of the south throughout the next couple of weeks. This will help with the drought a lot!

[srainhoutx]

Keep an eye on the 10th -15th time frame. The 12Z GFS suggests a impressive Arctic High (near 1060 mb) developing over AK and dropping S along the lee side of the Rockies bringing truly Arctic air very far S for most, if not all of the CONUS.

[Paul]

1060H? pfffttt... I will believe it when I see it.... Seems a tad on the extreme side, Steve.....with EPAC overrunning moisture it could make things interesting though....

[srainhoutx]

No doubt, Paul. Somewhat interesting to see the pattern now on the 12Z Euro. Notice those heights building across Canada and a cooperative STJ. Also notice how different the GOA (Gulf of Alaska) looks. Certainly a change from what we have seen and we are not looking 300+ hours out.

EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
1235 PM EST FRI DEC 31 2010

VALID 12Z MON JAN 03 2011 - 12Z FRI JAN 07 2011


PRELIMINARY UPDATE...

USED THE 00Z ECMWF TO UPDATE THE PRELIMINARY FRONTS AND PRESSURES
FOR DAYS 3 AND 4...AND THE 00Z ECENS MEAN THEREAFTER. THE MOST
CONSISTENT GUIDANCE OVER THE PAST FOUR MODEL CYCLES HAS BEEN THE
EUROPEAN CENTRE ENSEMBLE MEAN. THIS ENSEMBLE PACKAGE HAS SHOWN
LOTS OF SPREAD AMONG ITS INDIVIDUAL MEMBERS DEPICTING SHORTWAVE
DETAILS OVER THE EASTERN PACIFIC AND THE UNITED STATES EAST OF THE
ROCKIES. THE UKMET IS A DEVELOPED OUTLIER WITH THE CYCLONE IT
SPINS UP OVER THE EAST MID PERIOD...WITH THE GEM GLOBAL ON ITS OWN
WITH THE STRENGTH OF THE STORM OVER THE EASTERN PACIFIC AT THE END
OF THE FORECAST. THE DETERMINISTIC RUNS OF BOTH THE GFS AND ECMWF
HAVE BEEN JUMPY WITH THESE DETAILS...OWING TO THE PREDOMINATELY
ZONAL COMPONENT TO THE OVERALL FLOW.

FINAL...

UNFORTUNATELY...THE ADVENT OF THE 12Z GUIDANCE HAS AFFORDED NO
FURTHER CLARITY TO THE BEHAVIOR OF THE SHORTWAVES DURING THE
MEDIUM RANGE. THE GFS SHOWS AN ARCTIC HIGH DROPPING THROUGH THE
PLAINS DAY 7...WHILE THE GEM GLOBAL LOWERS PRESSURES OVER THE SAME
REGION AS A NORTHERN STREAM CYCLONE SWOOPS THROUGH THE GREAT
LAKES. THE RELIANCE ON THE ROBUST ECENS MEAN FOR MUCH OF THE
UPDATE PACKAGE SHOULD SERVE THE FINAL ISSUANCE JUST AS WELL.


CISCO

[cisa]

Happy New Year guys. Any indication of winter precip in Jan?