Forecast Discussions mentioning ACARS, received at FSL on 03/31/01

SAT IMAGERY AND TX 88DS SHOW LIGHT CONVECTIVE SHOWERS MOVING ACROSS THE CWA. RECENT ACARS SOUNDINGS SHOW STEEP MID LEVEL LAPSE RATES...BUT THE CORRESPONDING DRY AIR IS LIMITING DEVELOPMENT. THE MAIN FORECAST ISSUES ARE REMAINING POPS TONIGHT...POPS SAT...TEMPS SUN-MON...POPS TUE-WED...AND TEMPS AGAIN THU-FRI.

THE 12Z NCEP MODELS ARE IN FAIR AGREEMENT...PREFER THE ETA FOR ASSUMED BETTER HANDLING OF COLD AIR SURGE ON SAT...BUT THE FORECAST IS A BLEND OF ALL GUIDANCE. FWC/MAV TEMPS ARE PICK'EM IN THE SHORT TERM...AND MEX TEMPS LOOK REASONABLE IN THE EXTENDED RANGE.

LOOK FOR SHOWERS TO TAPER OFF TONIGHT AS HEATING WANES AND THE ASSOCIATED SHORT WAVE MOVES EAST. WILL USE ISOLATED EVENING POP WORDING TO HANDLE THE REMAINING STRAGGLERS. SAT POSES THE BIGGEST PROBLEM AS THE SHORT WAVE TROUGH TRACKS NE OF OUR AREA...AND THE COLD FRONT ARRIVES IN THE LATE AFTERNOON IN THE NWRN ZONES AROUND PEAK HEATING. ETA MODEL SOUNDINGS INDICATE NEARLY LINEAR 0-6KM SHEAR AROUND 30 M/S AND CAPES POSSIBLY IN THE 500-1000 J/KG RANGE TOMORROW AFTERNOON. IN ADDITION...THE FRZ/WBZ LEVELS ARE VERY LOW IN THE 88-9300 FT AGL RANGE. A NEGATIVE FACTOR ARE THE PROGGED MID LEVEL LAPSE RATES AROUND 6C/KM. OVERALL...WILL GO WITH 40 PCT POPS NORTH AND 30 PCT SOUTH AND ISSUE AN SPS/HWO FOR ISOLATED SEVERE THREAT GIVEN WEEKEND PLANNING. LATER SHIFTS MAY HAVE TO UPGRADE/REDUCE THE THREAT.

BREEZY WITH THE FROPA...BUT THEN WINDS DYING OFF QUICKLY AS HIGH PRESSURE CENTERS OVER SERN TX ON SUN. MON WILL ALSO BE MILD AND DRY...BUT THEN BREEZY WITH INCREASING CLOUDS AND CHANCE POPS TUE/WED AS THE NEXT SYSTEM EJECTS INTO THE PLAINS. WILL KEEP SLIGHT CHANCE POPS FOR THU AT THIS TIME AND FRI DRY.

.HGX...NONE.

31/35/39

PRELIMS... CLL BU 047/072 047/072 051 142 IAH BU 049/074 049/073 053 143 GLS BU 058/071 057/069 060 133



OVERALL...WEAK PRESSURE GRADIENTS THIS EVENING...SOME ONSHORE AND SOME OFFSHORE. LAX-DAG SHOWING THE STRONGEST ONSHORE GRADIENT AT 2.9. LOW CLOUDS AND FOG DEVELOPED OR MOVED INLAND QUICKLY THIS EVENING AT COASTAL SITES FROM SBA TO LAX. ACARS SHOWING MARINE LAYER AROUND 800 FT AT LAX...WHICH IS LOWER THAN EARLIER TODAY. WITH MARINE LAYER BELOW 1000 FT...FEEL THAT AT LEAST LOCALLY DENSE FOG WILL NEED TO BE ADDED TO SOUTH COASTAL ZONES. DFA MAY BE ISSUED IF WE GET MORE CONSISTENT COVERAGE OF 1/4 VSBYS. SO FAR...SBA/OXR/NTD HAVE BEEN FLIRTING WITH DENSE FOG...BUT HAVE NOT BEEN ABLE TO SUSTAIN IT.

REST OF THE WEEKEND LOOKS PRETTY TRANQUIL WITH WEAK NIGHTTIME GRADIENTS GIVING WAY TO STRONGER ONSHORE FLOWS WITH DAYTIME HEATING. PLENTY OF SUN INLAND TO YIELD HIGHS AT OR ABOVE TODAYS READINGS. CHANGES COMING AT THE BEGINNING OF NEXT WEEK AS AN INSIDE SLIDER LEADS THE WAY FOR PUSUANT SHORT WAVES TO DIG OUT A WEST COAST TROUGH...AND POSSIBLY DEALING WITH A CUT-OFF LOW BY MID WEEK OFF THE SRN CA COAST. NW FLOW ON OUTER WATERS STRENTGHENS MONDAY...WHICH LOOKS TO IN TURN STRENGTHEN EDDY CIRCULATION BRIEFLY BEFORE COLDER AIR MOVING IN ALOFT ERODES THE MARINE INVERSION. AVN/MRF INDICATE A RATHER STRONG SFC LOW DEVELOPING OVER THE GREAT BASIN MONDAY AND TUESDAY...WHICH COULD CREATE QUITE A WINDY COUPLE OF DAYS HERE. BEST CHC OF SHOWERS WILL COME WED/THU...ALTHOUGH THIS HIGHLY DEPENDENT ON EXACT PATH OR DEVELOPMENT OF CLOSED/CUT-OFF UPPER LOW. NONETHELESS...COOLER TEMPS APPEAR CERTAIN NEXT WEEK.

LAX 0000. MOYER.

.LAX...NONE.



WILL OPT TO UPDATE GOING ZFP TO MAKE A FEW CHANGES.

WK RIDGE OF HI PRESS TO BUILD ACRS THE GREAT LKS REGION/ONT/WRN QUE TODAY...AS A STORM SYS MOVES JUST TO THE SOUTH OF THE CANADIAN MARITIMES. THIS RIDGE TO BUILD ACRS THE FA FROM THE WEST TONITE AS ANOTHER WK STORM SYS MOVES OFF OF THE EAST COAST. WK S/W TO MOVE ACRS THE MID-ATLANTIC REGION AND INTO NY STATE TODAY. EASTERLY FLOW ALOFT ACRS THE FA TO WEAKEN WITH TIME INTO TONITE.

12Z RUC SHOWS TEMPS TO GET UP INTO THE 30S TODAY. T1MAX TEMPS ARE 35- 40 DEG F TODAY. LT WINDS TO PERSIST ACRS MUCH OF THE FA TODAY. MID- LVL MOISTURE TO LINGER ACRS THE NRN TIER ZONES TODAY. LOW-LVL MOISTURE TO LINGER ACRS THE ENTIRE FA TODAY. RUC INDICATING MEASURABLE PCPN TO CONT TO MOVE OUT OF THE NE KINGDOM TODAY WITH MAYBE SOME MEASURABLE PCPN (MOSTLY SN) ACRS THE MTNS FOR THE REST OF TODAY. PW VALUES TO BE AROUND A THIRD OF AN INCH TODAY AND TONITE.

WK H85 CAA TO TAKE PLACE ACRS THE FA TONITE...NEUTRAL ADVECTION TONITE. MID-LVL MOISTURE TO CONT TO LINGER ACRS THE NRN TIER ZONES TONITE. LOW-LVL MOISTURE TO HANG TUFF AS WELL ACRS THE ENTIRE FA TONITE. 925 MB WET-BULB TEMPS TO STAY NEGATIVE THRU TONITE. 12Z ACARS SOUNDING OUT OF KBTV SHOWED THAT THE ATMOSPHERE WAS PLENTY COLD ENUFF ALOFT FOR ANY PCPN TO BE SOLID IN NATURE. IR CLD TOPS SHOW THAT SOME PARTS OF THE FA HAVE THE POTNL TO SEE SOME LIQUID PCPN THOUGH.

IN ANY EVENT...DON/T EXPECT MUCH IN THE WAY OF MEASURABLE PCPN TODAY...SO WILL DROP THE POPS AND JUST MENTION THE CHC FOR SOME FLURRIES/DZ. HAVE ALSO ADDED THE POSSIBILITY THAT ANY PCPN TONITE WOULD BE TRACE IN NATURE AS WELL. WILL RE-EXAMINE THIS MINOR DETAIL FOR THE AFTERNOON PACKAGE.

VIS SAT PIX SHOW PLENTY OF CLDS ACRS THE FA ATTM AND ANY HOLES SHOULD FILL IN PRETTY QUICK. WITH NO SUNSHINE EXPECTED TODAY SO HAVE LOWERED HI TEMPS FOR TODAY AND WIDENED UP SOME OF THE RANGES IN A FEW ZONES. FEW TWEAKS TO FIRST PERIOD WINDS BASED ON CURRENT OBS AND RUC DATA. REMAINDER OF CHANGES TO GOING ZFP COSMETIC.

WORK ZONES OUT UNDER ALBWRKCWF. FINAL ZFP BY 11 AM. PNS BEING WORKED ON ATTM WITH SN STORM TOTALS A WILL BE ISSUED SHORTLY.

.BTV...NONE.

MURRAY