AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE AMARILLO TX 604 AM CDT MON JUL 1 2013 .AVIATION... VFR CONDITIONS TO PREVAIL THROUGHOUT THIS TAF ISSUANCE WITH LIGHT SURFACE WINDS. THERE IS A CHANCE FOR AFTERNOON CONVECTION AT KDHT SO RETAINED VCTS MENTION FROM THE PREVIOUS ISSUANCE. CONVECTIVE CHANCES FOR KAMA AND KGUY REMAIN LOW GIVEN THE MERIDIONAL ORIENTATION OF THE UPPER LEVEL FLOW. && .PREV DISCUSSION... /ISSUED 430 AM CDT MON JUL 1 2013/ DISCUSSION... INTERMITTENT THUNDERSTORM CHANCES WILL CONTINUE THROUGH THE WEEK...ALONG WITH COOLER TEMPERATURES. A HIGHLY AMPLITUDE UPPER FLOW PERSISTS ACROSS THE CONUS EARLY THIS MORNING...COMPRISED OF A DOMINANT UPPER RIDGE OVER THE WEST AND AN UPPER TROUGH OVER THE EAST. THE PLAINS STATES REMAIN SANDWICHED BETWEEN THESE TWO DOMINANT PRESSURE SYSTEMS...RESULTING IN A HIGHLY MERIDIONAL UPPER FLOW. A BROAD AREA OF SURFACE HIGH PRESSURE WAS SPRAWLED SOUTHWARD FROM SOUTHERN CANADA ACROSS THE PLAINS INTO TX. CONVECTION THAT AFFECTED PORTIONS OF THE PANHANDLES LAST EVENING HAS PUSHED SOUTH OF THE AREA...CURRENTLY MOVING ACROSS SOUTHEAST NM AND THE WESTERN TX SOUTH PLAINS. MEANWHILE UPSTREAM ACROSS SOUTHWEST NE AND NORTHEAST CO...ANOTHER SMALL CLUSTER OF SHOWERS AND THUNDERSTORMS HAS DEVELOPED. THESE APPEAR TO BE TIED TO THE LFQ OF AN UPPER JET STREAK DIVING SOUTH IN THE MERIDIONAL UPPER FLOW...AND MAY BE GETTING SOME SECONDARY LIFT FROM LOW-LEVEL UPSLOPE FLOW. SHOWER AND THUNDERSTORM CHANCES WILL CONTINUE THE NEXT SEVERAL DAYS...AND OVERALL WILL FAVOR THE WESTERN HALF OF THE PANHANDLES...PARTICULARLY THE NEXT COUPLE OF DAYS. CONVECTION CURRENTLY OVER SOUTHWEST NE/NORTHEAST CO WILL CONTINUE TO PROPAGATE SOUTH TODAY...EVENTUALLY INTO THE PANHANDLES...AS THE SUPPORTING UPPER JET STREAK DIVES SOUTH. WILL ALSO LIKELY SEE SOME CONVECTION FIRE OVER THE HIGHER TERRAIN OF CO AND NM ONCE AGAIN TODAY. NORTH TO SLIGHTLY NORTHWEST STEERING FLOW MAY ALLOW THIS HIGHER TERRAIN CONVECTION TO CLIP THE WESTERN PANHANDLES...BUT THE PRIMARILY NORTHERLY STEERING FLOW WILL PREVENT IT FROM MAKING MUCH EASTWARD PROGRESS INTO THE PANHANDLES. THE PATTERN TUESDAY WILL REMAIN VERY SIMILAR TO TODAY...AGAIN WITH THE WESTERN PANHANDLES FAVORED FOR RAIN CHANCES DUE TO THE TRAJECTORY OF ANY MID/UPPER-LEVEL JET STREAKS/WEAK SHORTWAVES AND THE NORTHERLY STEERING FLOW. THE COMBINATION OF LIMITED LOW-LEVEL MOISTURE IN WEAK UPSLOPE FLOW AROUND THE BROAD SURFACE RIDGE /SURFACE DEWPOINTS 40S TO LOWER 50S/...COOL BOUNDARY LAYER TEMPERATURES...AND WEAK MID-LEVEL LAPSE RATES WILL REALLY LIMIT INSTABILITY TODAY AND TUESDAY /MLCAPE VALUES AROUND 500 J/KG OR LESS/. THUS DESPITE MORE THAN SUFFICIENT DEEP LAYER SHEAR /40 KTS OR MORE ACROSS THE WESTERN PANHANDLES/ FOR STORM ORGANIZATION BENEATH THE ENHANCED NORTHERLY FLOW ALOFT...THE THREAT FOR ANY SEVERE WEATHER IS VERY LOW. COULD SEE A FEW STRONG STORMS WITH GUSTY WINDS AND SMALL HAIL ACROSS THE WESTERN PANHANDLES DURING THE AFTERNOON AND EVENING HOURS...BUT NOT EXPECTING ANYTHING SEVERE AT THIS POINT. BY WEDNESDAY THUNDERSTORM CHANCES EXPAND FARTHER EAST ACROSS THE FORECAST AREA. STRONGER INSTABILITY AND INDICATIONS OF A STRONGER MID-LEVEL SHORTWAVE POSSIBLY ROTATING THROUGH THE NORTHERLY FLOW ALOFT SUGGEST A LITTLE BETTER SHOWER AND THUNDERSTORM CHANCES WEDNESDAY...AND A LITTLE HIGHER THREAT FOR SOME STRONG TO SEVERE CONVECTION...ALTHOUGH ANY ORGANIZED OR WIDESPREAD SEVERE WEATHER APPEARS UNLIKELY. MODELS CONTINUE TO TREND DRIER FOR INDEPENDENCE DAY AS THE UPPER TROUGH TO OUR EAST BEGINS TO WEAKEN. HUNG ONTO SOME SLIGHT CHANCE POPS ACROSS SOUTHERN AND WESTERN PORTIONS OF THE CWA...HOWEVER IT/S REALLY STARTING TO LOOK LIKE MOST PLACES WILL STAY DRY. CAN/T RULE OUT A SHOWER OR STORM ACROSS THE SOUTHEAST TX PANHANDLE THURSDAY MORNING IN CLOSER PROXIMITY TO THE BASE OF THE UPPER TROUGH...AND SOME HIGHER TERRAIN CONVECTION COULD POSSIBLY AFFECT THE WESTERN PANHANDLES DURING THE AFTERNOON AND EVENING...ALTHOUGH THE NORTHERLY STEERING FLOW WILL LIKELY LIMIT THIS THREAT TO NEAR THE NM STATE LINE. HAVE PULLED POPS FOR THURSDAY EVENING FROM ALL AREAS EXCEPT THE FAR WESTERN PANHANDLES...AND BOTH THE THURSDAY AND THURSDAY NIGHT POPS MAY NEED TO BE LOWERED FURTHER IF MODEL TRENDS CONTINUE. A FEW ISOLATED STORMS COULD CLIP PARTS OF THE WESTERN PANHANDLES FRIDAY AND SATURDAY AFTERNOON AND EVENING...BUT OVERALL PRECIP CHANCES LOOK PRETTY LIMITED BY THIS TIME AS HEIGHTS RISE ALOFT AND THE STEERING FLOW REMAINS NORTHERLY...WHICH WILL KEEP MOST OF ANY CO/NM MOUNTAIN CONVECTION TO OUR WEST. SOME UNCERTAINTY ARISES BY THE LATTER HALF OF THE WEEKEND REGARDING THE EVOLUTION OF A MEANDERING WEAK MID/UPPER-LEVEL LOW REMNANT FROM THE BASE OF THE CURRENT EASTERN UPPER TROUGH. MODELS SUGGEST THIS FEATURE COULD MEANDER WEST TOWARD THE PANHANDLES...POSSIBLY BRINGING A CHANCE FOR SHOWERS AND THUNDERSTORMS...BUT CONFIDENCE WITH THE EVOLUTION/MOVEMENT OF ANY SUCH FEATURE NEARLY A WEEK OUT IS EXTREMELY LOW...SO WILL KEEP THE FORECAST DRY FOR NOW ESPECIALLY SINCE IT APPEARS ANY INFLUENCE WOULD MOST LIKELY STAY EAST AND/OR SOUTH OF THE CWA. TEMPERATURES WILL REMAIN PLEASANTLY COOL FOR EARLY JULY THE NEXT SEVERAL DAYS...BEFORE BEGINNING TO REBOUND FRIDAY INTO NEXT WEEKEND AS HEIGHTS RISE AND SOUTHERLY LOW-LEVEL FLOW STRENGTHENS. KB FIRE WEATHER... NO ELEVATED OR CRITICAL FIRE WEATHER CONDITIONS ARE EXPECTED OVER THE NEXT SEVERAL DAYS DUE TO MINIMUM RELATIVE HUMIDITY VALUES ABOVE 20 PERCENT...INTERMITTENT SHOWER AND THUNDERSTORM CHANCES...AND 20 FOOT WINDS GENERALLY STAYING NEAR OR BELOW 15 MPH. KB && .AMA WATCHES/WARNINGS/ADVISORIES... TX...NONE. OK...NONE. && $$ 14/08
Posted on: Mon, 01 Jul 2013 12:04:24 +0000
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