FXUS04 KWBC 122217 PAA QPFPFD QUANTITATIVE PRECIPITATION FORECAST DISCUSSION NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD 515 PM EST WED FEB 12 2003 FINAL DAY 1...DAY 2 AND DAY 3 QPF DISCUSSION VALID FEB 14/0000 UTC THRU FEB 16/0000 UTC REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR DAY 1... ....SWRN U.S.... THE MODELS CONTINUE TO ADVERTISE SIGNIFICANT RAINFALL OVER AZ THIS PD AS DEEP SLY FLOW DELIVERS ABUNDANT MOISTURE TO THE AREA. BUMPED UP AMNTS SLIGHTLY ACROSS AZ AND PORTIONS OF NV BECAUSE OF THE CONSENSUS OF THE 06Z ETA AND GFS RUNS. THE SLY FLOW SHOULD PRODUCE DECENT OROGRAPHIC LIFTING ALONG THE S FACING SLOPES OF THE MOGOLLON RIM COUNTRY AND OTHER MTNS TO THE S. THE 1200 UTC MODELS CONTINUE TO INDICATE THAT THE UPPER TROF OFF THE CA COAST WILL ADVANCE SLOWLY EWD AND OPEN UP THRU THE FCST WHICH WILL BRING THE DEEP-LAYERED SUBTROPICAL MSTR PLUME FM SRM CA EWD INTO THE SWRN U.S. PER LATEST STLT IMAGERY THERE ARE PWS IN EXCESS OF 1.50 INCHES CURRENTLY EMBEDDED IN THIS PLUME...THE BULK OF WHICH SHOULD EVENTUALLY WORK ITS WAY NWD ACROSS THE BAJA TO SUPPORT A HVY RNFL EVENT. THE MODELS ARE UNFORTUNATELY NOT IN THE GREATEST AGREEMENT HANDLING THE UPPER VORTS BEING EJECTED FM OR ROTATING AROUND THE UPPER TROF. HENCE THEIR QPF EMPHASIS IS NOT VERY COINCIDENTAL... ESPECIALLY NORTH OF SRN CA AND AZ. OVR CNTRL/NRN CA AND OR...STAYED CLOSER TO THE ETA WHOSE QPF SEEMED TO BETTER REFLECT TWO VORTS NOW LIFTING NWD NEAR THE NRN AND EXTRM SRN CA COAST RESPECTIVELY. GREATEST CONFIDENCE IN THE QPF IS OVER THE MTNS OF SRN CA AND E CNTRL AND CNTRL AZ. OVER THE LATTER...THE DEEP-LAYERED SLY FLOW WILL IMPINGE ON THE MTNS THERE RESULTING IN A LONG DURATION AND VERY HVY RNFL EVENT. HAVE VERY LITTLE CONFIDENCE IN THE QPF OVR THE CNTRL /NRN GREAT BASIN AND BASICALLY ATTEMPTED A COMPROMISE BTWN MODEL QPFS THERE GIVEN THE MANY MINOR DIFFERENCES OBSERVED IN THE MASS FIELDS FCSTS THERE. ...SRN PLAINS/LWR MS VLY... AS SHRTWV ENERGY BEING EJECTED FM THE WEST COAST UPPER TROF WORKS TO THE SRN PLAINS...IT WILL TAP MSTR ALREADY OBSERVED RETURNING FM THE WRN GULF. AGAIN THE MODEL MASS FIELDS HAVE MINOR DIFFERENCES HANDLING THE PIECES OF SHRTWV ENERGY THAT IS RESULTING IN SOME LARGE QPF DISCREPANCIES. HOWEVER...ON THE BROADER SCALE...BOTH THE ETA AND GFS RH FIELDS ARE IN REASONABLE AGREEMENT AND GIVEN THE UNCERTAINTY...ATTEMPTED TO DRAW A QPF THAT REFLECTED THESE FIELDS. DAY 2... ...18Z MODEL UPDATE... THE 18Z ETA TRENDED A BIT STRONGER WITH THE DEVELOPING SURFACE LOW IN THE CENTRAL/SRN PLAINS OR SLIGHTLY CLOSER TO THE GFS/UKMET SOLUTION FROM 12Z THIS MORNING. MANUAL QPF ONLY MADE A FEW MINOR CHANGES TO THE DAY 2 QPF IN THE CENTRAL PLAINS SPREADING INTO THE OH/TN VLYS. ...SRN PLAINS/LWR MS VLY/MID MS VLY/OH VLY/SOUTH/MID-ATL... VERY COMPLICATED FCST COMING UP FOR DAY 2 FOR THE ERN 2/3 OF THE US... AS MODEL GUIDANCE DIFFER SIGNIFICANTLY WITH THE SHORT WAVE ENERGY MOVING INTO THE PLAINS. THE 12Z GFS/UKMET IS MUCH STRONGER WITH THE MID-LEVEL ENERGY SHOOTING OUT INTO THE PLAINS... LEADING TO A DEEPER AND FARTHER NORTH SURFACE LOW. THE ETA REMAINS SUPPRESSED AND WEAKER WITH THE SHORT WAVE ENERGY BUT NOT AS MUCH AS YESTERDAYS RUN 12Z RUN. IN FACT... THE 12Z/12 ETA LOOKS MORE LIKE THE 12Z/11 GFS/UKMET. MID-LEVEL TROUGH MOVES INTO THE PLAINS AROUND 42 HRS WITH A SURFACE LOW DEVELOPING IN THE CENTRAL/SRN PLAINS. THIS SHORT WAVE ENERGY IS A PRELUDE TO THE STRONG UPPER LOW... OFF THE CA COAST AT THIS TIME... IN THE SWRN US. THE FAST UPPER FLOW ALONG THE SRN STREAM SHOULD ADVECT THE INITIAL SHORT WAVE ENERGY AND SURFACE LOW QUICKLY INTO THE ERN OH VLY/MID-ATL. A COLD FRONT WILL DIVE DOWN THE FRONT RANGE OF THE ROCKIES AND HELP ESTABLISH/KEEP THE COLD AIR MASS IN PLACE OVER THE NRN PLAINS/MID MS VLY/OH VLY AND INTO THE MID-ATL. THIS FRONT WILL DRAPE OVER THE SRN STREAM LOW AND ASSOCIATED WARM FRONT... WHICH WILL PROVIDE THE LEADING EDGE OF A VERY STRONG LLJ AT 850 MB AND TREMENDOUS WAA. MEANWHILE... A STRONG SURGE OF GULF MOISTURE ALONG WITH A FETCH OF SUBTROPICAL MOISTURE WILL SPREAD OUT AHEAD OF THE SYSTEM SETTING UP A VERY HEAVY RAIN EVENT WITH THE POSSIBILITY OF ICE/SNOW ALONG THE NRN TIER OF THE PRECIP AND EAST OF THE APPALACHIANS. MANUAL QPF ENDED UP GOING WITH A BLEND OR COMPROMISE OF THE GFS/ETA... LIKED THE ETA IDEA OF A MORE SUPPRESSED SYSTEM AND WEAKER WAVE/SURFACE LOW MOVING ALONG THE FAST FLOW BUT ALSO LIKED THE GFS THINKING OF SPREADING THE PRECIP FASTER TO THE EAST THAN THE SLOWER ETA. AS A RESULT... CONFIDENCE IS LOW WITH THIS FORECAST. SEE THE QPFHSD FOR MORE ON WINTER WEATHER POSSIBILITIES FOR DAY 2. ...WEST... THE LARGE UPPER LOW OFF THE CA COAST... AT THIS TIME... BEGINS TO SPREAD INTO THE INTER-MOUNTAIN AND ESPECIALLY THE SWRN US. MEANWHILE... THE UPPER RIDGE OVER THE PAC NW BEGINS TO BREAK DOWN ALLOWING A LIGHT ONSHORE FLOW DEVELOP. MOISTURE IS GOING TO REMAIN MUCH OF A QUESTION MARK THROUGHOUT THE REGION ON DAY 2. THE BEST CHANCES FOR MDT PRECIP CHANCES WILL BE AROUND THE MID-LEVEL LOW OR REMNANTS OF IN THE SOUTHWEST... BOTH THE ETA AND GFS ARE SIMILAR IN DRAWING PWS AOA .75 INCHES INTO AZ TO INTERACT WITH PVA. EXPECT ANOTHER MDT PRECIP EVENT FOR AZ ESPECIALLY HIGHER ELEVS. DAY 3... ...OH VLY/MID MS VLY/TN VLY/LWR MS VLY/SOUTH/MID-ATL/NORTHEAST... THE SHORT WAVE ENERGY MOVING QUICKLY INTO THE OH VLY ON DAY 2 BEGINS TO MOVE OFF THE MID-ATL COASTLINE... WHILE MORE SHORT WAVE ENERGY AND THE ORIGINAL UPPER LOW KICK OUT OF THE SOUTHWEST INTO TX AND THE SOUTH. A FRONTAL BOUNDARY WILL BE DRAPED FROM THE MID-ATL REGION INTO THE SRN PLAINS/TX WHILE A PRE-FRONTAL TROUGH EXTENDS EAST INTO THE DEEP SOUTH. COLD AIR WILL BE ENTRENCHED AND ENHANCED AS THIS FRONT SLOWLY DRIFTS TO THE SOUTH ALLOWING SOME AREAS IN THE SRN NEW ENGLAND ARE TO REMAIN ALL SNOW AND AREAS SOUTH AND WEST (IN THE MID-ATL/OH VLY/MID MS VLY) TO CHANGE TO ALL SNOW BY THE END OF THE PERIOD. THE GFS AND ETA STILL SHOW A VERY ACTIVE LLJ ACROSS THE SOUTH OR JUST AHEAD OF THE FRONT ALLOWING PLENTY OF MOISTURE TO STRETCH OUT AHEAD OF IT. THERE ARE MANY DIFFERENCES BETWEEN THE TWO MODELS... THE SPEED OF THE MAIN TROUGH COMING OUT OF THE SOUTHWEST... THE DEPTH AND STRENGTH OF THE UPPER TROUGH... WHERE THE HEAVIEST PRECIP AXIS WILL SET UP AND FINALLY THE STRENGTH OF THE ARCTIC HIGH TO THE NORTH PUSHING THE COLD AIR INTO PLACE. MANUAL QPF... ONCE AGAIN... WENT WITH A BLEND OF THE GFS/ETA OR COMPROMISE BETWEEN THE TWO. MAX PRECIP AREAS WILL CONCENTRATE WITH THE EXITING SHORT WAVE IN THE MID-ATL INTO THE ATL... THE SURFACE LOW PRESSING FROM THE WRN OH VLY TOWARD THE SRN APPALACHIANS AND AHEAD OF THE PRE-FRONTAL TROUGH WHERE CONDITIONS SHOULD BE FAVORABLE FOR SOME CONVECTION. ...WEST COAST... THE GFS AND ETA HANDLE THE APPROACHING UPPER TROUGH AND FRONTAL BOUNDARY TOWARD THE WEST COAST DIFFERENTLY. THE GFS IS MORE PROGRESSIVE ALLOWING A SIGNIFICANT SHORT WAVE TO DIVE DOWN THE BASE OF THE TROUGH AND APPROACH THE NRN/CENTRAL CA. THE ETA IS SLOWER AND DOES NOT DEPICT THE VERY STRONG SHORT WAVE THE GFS HAD... MORE OF A STRING OF VORTICITY STRETCHING FROM WA INTO THE PAC. BEING DAY 3 AND MODELS NOT VERY SIMILAR... MANUAL QPF WENT WITH ANOTHER COMPROMISE OF THE TWO... CONCENTRATING THE BEST LLJ INFLOW AROUND NORTH CENTRAL CA WITH OVER AN INCH OF PRECIP IN THE HIER ELEVS OF NRN CA. KORTY/MUSHER GRAPHICS AVAILABLE ON THE WEB AT http://www.hpc.ncep.noaa.gov 24HR QP VT 14/00Z 0.01 472686 470683 467682 464683 459687 457690 453696 451699 446704 441710 440712 443714 446713 451709 456705 461702 467698 470693 472686 0.01 483877 482866 479855 478850 474843 471838 468836 465832 461824 460813 459806 459801 457797 455793 449784 445777 443768 448739 444735 438736 430740 427746 425753 424765 423770 419777 417778 413778 401781 392787 383794 375802 372808 371814 372818 375818 380815 398804 405804 406804 409808 415819 419820 423821 432825 441831 445834 448837 448842 445847 442850 437853 434855 431855 426854 422856 420860 421864 423867 427870 436870 446870 454870 458872 461879 462888 463897 465903 468904 471903 478899 481893 483887 483877 0.01 480164 479159 476155 471148 465143 461140 458135 453121 454116 455109 451100 446096 439093 429086 425085 421088 418093 411087 403088 404083 406080 410075 412070 413065 410059 406056 399057 393061 386062 383064 379062 378057 382058 387055 390054 391051 389047 385047 379046 371045 362047 354048 349044 346038 347030 350015 350006 353002 355998 358996 365995 371997 378998 384997 391994 395988 396981 395975 391968 386962 369940 364930 357917 353911 350906 345901 339898 332897 329900 328904 325911 324921 323927 322934 318940 314944 307947 302951 299956 297962 299968 303972 305976 303980 293992 290997 286005 286008 290014 295018 301019 309019 312025 314032 317038 318042 316049 316055 310058 304061 297065 292071 290077 288084 286094 286101 288108 292117 296129 299136 301142 303149 301158 301163 302167 307174 316184 326195 332204 338212 349221 358228 364233 370237 378241 387246 403253 411255 417255 430252 440250 448250 454251 462251 464251 467246 468240 466236 462229 460220 457217 452214 443212 438212 433209 428205 424199 422198 424196 426194 430193 432193 435194 438201 442205 451197 455189 459186 462181 459173 460168 464167 472170 478167 480164 0.01 415192 414190 414188 412185 409184 407183 406182 404182 406184 406186 405190 405191 404194 404196 405198 407200 409202 409203 410203 411199 413196 413195 415192 0.01 401185 400185 397183 394183 392181 389179 389179 386178 385178 383180 382182 383184 384186 385186 388187 391190 392191 393191 394191 396190 398188 400186 401185 0.25 445228 444224 441221 436221 433223 430224 428228 425234 422235 418232 416230 415225 416220 415217 414215 411213 404208 398203 384195 379191 374184 369176 368172 369169 372167 375166 379165 384168 388168 390166 391154 395150 396145 395143 387112 383106 383102 386094 386087 383081 378072 375067 371065 367066 363069 367072 367083 365085 361084 351083 345079 341074 336071 328070 324073 321078 319082 316083 309085 303091 301097 299106 300115 301120 306133 310140 315146 317149 317154 316159 316163 318168 321174 328183 334189 338197 341202 345206 351211 355215 360220 365224 372227 379228 386231 392236 401243 407245 415244 421245 427244 429239 431233 440232 445228 0.25 406110 406110 404106 403105 403106 400110 400110 397111 395113 397114 400115 403116 406114 406113 406110 0.25 367204 366203 364200 363199 361196 360195 358194 357191 356190 353190 353190 351193 352196 354197 355199 357201 358202 360204 362205 365206 367204 0.25 358107 357106 355106 354107 355107 357107 358107 0.25 347944 346935 344927 342922 340920 337920 333930 329942 326955 324967 324974 325981 329985 331986 334984 339975 343963 346951 347944 0.25 338062 338058 335056 333055 333054 330054 327054 325055 326058 327059 330061 333061 334062 335062 338062 0.50 413235 412227 413219 410217 405214 402212 398207 394205 389205 386208 390213 393215 398218 404220 405225 405229 408233 413235 0.50 385149 384145 381143 379134 379131 382124 379119 377119 371118 366115 359113 354110 351105 349100 350096 343086 339081 335077 331076 327078 324085 322089 316089 309092 306097 304101 303106 304110 309123 312133 317139 321142 332149 338152 346153 352155 357158 362167 366162 368156 373152 380153 383152 385149 0.50 350200 349196 348189 348179 347168 345164 342164 337163 334161 328160 323161 321165 322168 324173 327175 332179 334183 338191 339195 342198 346202 349202 350200 1.00 360124 361121 360120 358117 354113 348108 345103 338089 335085 332085 332088 331099 324101 317103 315104 312107 313112 317113 320111 323110 326112 329115 328130 330133 334135 339138 343140 348140 350138 352134 360124 1.00 344185 345178 344171 342168 339167 336166 333165 328164 324165 325168 330172 334173 338177 339181 341184 342188 344185 1.50 355121 351114 347110 343104 339099 337098 337102 334105 332105 330108 332115 334121 334126 336131 343133 347132 351124 353124 355121 1.50 343181 344178 343176 342174 342171 341169 339170 340174 340177 341178 342181 343183 343181 2.00 346127 346123 346120 348117 347113 346111 345109 343107 340106 338109 337110 335112 334112 334113 335116 336119 337122 337122 337126 339128 342129 345129 346127 24HR QP VT 15/00Z 0.01 540207 541200 541192 536182 526163 520155 511147 495135 481124 476121 474117 476112 477105 475102 474094 471090 468090 465093 462098 459097 456093 454090 450089 436088 432088 428084 425083 422084 420088 416090 410088 407084 412079 417077 420064 419059 416056 410053 405051 400051 391054 385054 378048 375046 369046 361048 354051 344053 333053 324052 321051 317052 312061 307067 302077 294090 290095 293104 300120 308136 312143 317148 323151 327152 335155 343157 348160 353162 364164 373170 381173 384175 387179 390182 396183 405180 413180 414185 417190 420188 423190 427191 430187 430183 427179 426175 430174 437170 440169 443173 443179 441182 438186 437191 440196 443192 446191 448193 452195 456189 463183 465179 464174 468175 473175 476177 482186 490191 495196 498202 502201 507201 512203 514205 522215 526217 531221 535221 538215 0.01 525256 527246 527233 524227 519223 505214 501207 495202 484201 476199 469201 462203 460203 456205 451209 445211 433209 425198 421198 416195 412199 412203 415206 418211 423214 419217 417212 406202 404201 402199 400196 396192 393193 390191 389184 382183 374181 367179 363178 359179 352180 347180 346178 345171 345167 342165 335164 330162 327159 324158 321161 321166 321174 322179 326181 329183 335187 343195 349199 357202 360206 361214 363221 368223 377232 381238 385245 390249 394252 39