QUANTITATIVE PRECIPITATION FORECAST DISCUSSION NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD 227 AM EDT WED JUN 09 2010 PRELIM DAY 1 QPF DISCUSSION VALID JUN 09/1200 UTC THRU JUN 10/1200 UTC REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR DAY 1... ...NORTHEAST TO TN VLY/MID TO LWR MS VLY... LIKE THE LAST SEVERAL NIGHTS... NOT AN EASY FCST AS MODELS ARE HAVING DIFFICULTY HANDLING SHORT TERM CONVECTION/HEAVY RAIN WHICH IMPACTS THE REMAINING PORTION OF THE FCST PERIOD. ON THE LARGE SCALE THE MDLS DO AT LEAST AGREE THAT THERE WILL BE A H5 TROF AXIS ALONG WITH EMBEDDED SHRTWV DYNAMICS MOVG ACRS THE GRT LAKES/OH VLY ON WED BEFORE ARRIVING INTO THE NORTHEAST. ACCOMPANYING THIS FEATURE WILL BE A WELL-DEFINED SURFACE WAVE/COLD FRONT BUT THE SRN EXTENSION OF THIS FRONT WILL EVENTUALLY STALL BECOME STATIONARY FROM THE TN VLY BACK INTO SRN MO/NRN AR AND KS/NRN OK. HOWEVER...DESPITE THIS OVERALL LARGE MASS FIELD AGREEMENT...THE SMALLER SCALE DETAILS ONCE AGAIN ARE EXTREMELY TROUBLESOME AND VIRTUALLY IMPOSSIBLE TO PREDICT. A BROAD SHIELD OF CONVECTION/HEAVY RAIN IS SLICING ACROSS IL/IN BACK INTO SERN KS THIS MORNING... WHILE LIGHTER OVERRUNNING/STRATIFORM SHOWER ACTIVITY IS OUT AHEAD OF THIS CONVECTIVE ELEMENT OVER THE GRT LAKES INTO THE ERN OH VLY. ALL OF THIS ACTIVITY IS EXPECTED TO SLIDE DOWNSTREAM... LIKELY TO WEAKEN OR FALL APART DURING THE MORNING/MID AFTN HRS AND THEN RE-FIRE WITH STRONG DIURNAL HEATING. THIS IS ESPECIALLY TRUE FROM THE NRN MID-ATL REGION BACK INTO THE ERN TN VLY. ITS HERE IN THE TN VLY THAT MOST OF THE OPERATIONAL GUIDANCE IS PINPOINTING THE BEST FORCING... AS PW VALUES POOL AOA 2 INCHES. HPC FEELS IT HAS A SOLID HANDLING IN THE OVERALL QPF AXIS BUT AMOUNTS VERY TOUGH TO FCST... ESPECIALLY IN THE WARM SECTOR AND TAIL END OF THE FRONTAL AXIS. WHICH TAKES US TO THE IMPRESSIVE SLOW MOVING ACTIVITY ACROSS SERN KS... AT THE TAIL END OF THE THERMAL AXIS. THE MODEL GUIDANCE HAS A BETTER HANDLING OF THIS THAN PREVIOUS NIGHTS BUT STILL NOT ENOUGH AS THE ACTIVITY CONTINUES TO TRACK EXTREMELY SLOW AND BACK BUILD. HPC FEELS THAT EVEN AS THE BULK OF UPPER DYNAMICS PROGRESS DOWNSTREAM... ITS THE TAIL END OF THIS BOUNDARY THAT VERY WELL COULD BECOME ACTIVE AGAIN LATER THIS AFTN. OVERALL HPC TRIED TO STAY CLOSE TO THE OPERATIONAL ECMWF ON MASS FIELDS AND THE EC WITH THE SREF MEAN AND ENSBC QPF FOR QPF AMOUNTS. ...ERN TX... THE MDLS REMAIN REASONABLY WELL-CLUSTERED WITH THE IDEA OF TAKING A WELL-DEFINED MID-LEVEL CIRCULATION OVER SOUTH CENTRAL TX AND DRIFTING THIS FEATURE NEWD INTO NORTHEAST TX/SERN OK BY THURS MORNING. THE UPPER DYNAMICS WITH THIS FEATURE AND BROAD UPPER LIFT WILL COMBINE WITH A VRY MOIST AMS...PWATS IN EXCESS OF 2 INCHES...AND STRONG DIURNAL HEATING TO PRODUCE AT LEAST A BKN AXIS OF CONVECTION INVOLVING MUCH OF ERN TX. MOST OF THE OPERATIONAL GUIDANCE AND ENSEMBLE DATA SUGGEST LARGE QPF AMOUNTS MAINLY DUE TO THE EXTREMELY LIGHT STEERING FLOW... 15 KTS OR LESS AT 750/850 MB. THUS... HPC LEANED TWD THE WETTER MDL CAMP OF THE ECMWF/SREF MEAN AND ENSBC FOR QPF AMOUNTS BUT NOT AS WET AS THE GFS WHICH STILL APPEARS TO HAVE SOME CONVECTIVE FEEDBACK ISSUES. ONE ISSUE THOUGH... WORRIED THE GUIDANCE PERHAPS IT TOO BROAD BRUSHED WITH THE OVERALL EXPANSION/AXIS OF THE QPF OVER ERN TX. HPC DID NOT ISSUE ANY EXCESSIVE RAINFALL FCST HERE AS FFG VALUES ARE EXTREMELY HIGH BUT WITH LOCALLY 3 TO 4 INCH AMOUNTS POSSIBLE WITH THIS SEMI-TROPICAL FEATURE... SOME RUNOFF ISSUES ARE POSSIBLE LIKE AROUND SAT EARLY THIS MORNING. ...PAC NW INTO UPPER MIDWEST... A SOLID PAC SHRTWV/CLSD LOW FEATURE ARRIVING INTO THE PAC NW COASTLINE THIS MORNING...DRIVING A ROBUST TRANSPORT OF PAC MSTR INTO WA/OR... WILL SLOWLY PROCEED DOWNSTREAM OVER THE NEXT 24 HRS. THIS WILL ALLOW ANOMALOUS LOW UPPER HEIGHTS TO DIG ACROSS THE NWRN SECTION OF THE COUNTRY AND DRIVE LEAD SMALL SCALE IMPULSES TO EJECT INTO THE UPPER MIDWEST. EXPECT DEEP LYR ONSHORE FLOW AND FORCING FROM OROGRAPHICS TO DRIVE AT LEAST SOME MODERATELY HVY RAIN FOR THE COASTAL RANGES OF WA/OR INTO THE CASCADES AND CENTRAL/NRN ID. MEANWHILE... VERY DIFFICULT TO TRACK THE SMALL SCALE DETAILS ARRIVING INTO THE UPPER MIDWEST LATE WED/EARLY THURS BUT ALL MODELS DEVELOP A WELL-DEFINED WARM FRONTAL BOUNDARY FROM THE DAKOTAS SEWRD INTO ERN NE. EXPECT A BURST OF NOCTURNAL CONVECTION... WHILE MOST OF THE GUIDANCE PROGS A SOLID 30 TO 40 KT GREAT PLAINS LL JET DIRECTED INTO THIS BOUNDARY. HPC GENERALLY FOLLOWED A BLEND OF THE ECMWF/SREF MEAN AND ENSBC QPF FOR QPF AMOUNTS OVER THE 24 HRS FCST PERIOD. MUSHER GRAPHICS AVAILABLE ON THE WEB AT WWW.HPC.NCEP.NOAA.GOV 24HR QP VT 10/12Z 0.01 540207 540197 538190 538183 539175 540165 541153 542131 543114 543092 542085 540083 536075 529063 520050 517046 515042 515037 513030 510022 504004 497987 493978 489974 485972 473965 462958 455955 445951 435947 430945 426941 417932 408924 400924 395922 392913 392903 393894 394888 400882 409871 414867 418864 429855 432851 435849 438850 440851 442856 447875 455906 465923 478950 489957 493960 500960 507949 502935 500931 498928 498925 501921 506913 509907 514899 516892 515878 514865 512858 509853 503841 488815 484809 482803 477786 474775 473767 473759 471748 465732 459715 457710 454706 450701 441691 431682 428679 423676 413670 408668 401669 395671 390673 384677 379683 374689 369696 365704 361712 352731 345752 339775 337781 338788 339799 340807 338813 336821 333826 327836 325841 324846 324861 324868 323876 319883 314888 307899 305903 307907 311908 316908 320909 321911 322918 320919 316917 313914 306913 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478199 475195 473193 472193 470191 467190 464191 461193 460194 459198 460202 460203 462205 465205 468205 471203 474203 476203 0.01 470120 461124 458122 465118 472115 470120 0.01 465072 466066 466059 465047 464043 462038 457035 455034 455039 452047 449056 448061 449068 449074 447078 444080 444084 447090 453086 456086 459082 462076 465072 0.01 265800 260798 254798 249800 245805 243812 242818 243822 246825 254822 259824 264826 267826 269824 269819 267815 265806 265800 0.25 525203 527193 529182 530171 530160 531146 530137 528126 525116 523111 520105 515101 513100 508105 507116 506122 504127 501133 498139 493141 483138 480139 481144 480148 477149 473148 468142 465140 462141 458145 450151 444156 443162 449175 450180 454186 457187 459186 464182 469178 473177 477179 485187 489193 490199 487203 483207 477210 472211 458214 448213 441214 437216 431220 427224 417232 409236 405239 407245 414249 421250 432249 453246 465247 473248 482252 488254 492258 497263 498265 501266 507263 509261 511256 512244 512236 512223 514217 516214 522208 525203 0.25 450732 448722 445711 434698 428692 423688 415685 410684 404685 398687 391691 385698 380705 376711 373718 372722 372727 375735 377739 378744 380760 381779 382785 380789 375795 372799 368804 361807 357813 353821 351828 348834 345842 345857 345871 344881 344889 343893 344897 348903 356914 360918 362926 365949 366960 367968 370972 372967 375961 376953 378936 378915 379899 381892 383886 391872 399859 406847 411834 416819 424803 427800 430797 434796 438796 443800 448802 455804 459808 462809 464807 462799 460792 459785 461775 457760 452743 450732 0.25 497036 498030 497023 494014 489006 483002 477001 474003 472008 475020 477029 480037 482046 485050 488051 494045 496039 497036 0.25 452002 452994 450990 447985 443980 438974 431969 424961 421958 415956 410957 406961 403966 402976 402984 402988 401993 394996 390998 388006 391019 391023 394031 397033 402033 406030 411026 414018 416011 412007 418007 431008 439010 445010 449006 452002 0.25 343959 342951 338939 336937 333935 323937 316936 311936 306938 301943 296950 288962 285967 282975 284984 288990 293993 299995 304994 321989 328985 334978 341966 343959 0.50 526169 527158 526149 525139 522131 518131 516134 514136 513142 508159 502157 494156 484160 480165 480169 482173 486178 491182 497186 502191 506186 512185 516179 518177 521175 526169 0.50 503238 503231 502224 500219 496216 494213 491212 485214 485215 487220 492225 494230 496236 499241 500242 502242 503238 0.50 442719 429697 424693 419690 413689 407689 403689 397692 388700 384707 381713 380720 382729 385741 386749 386754 388772 388786 386791 383796 378801 375805 371809 367811 363812 360814 358819 351840 351844 352849 354853 354857 354865 355875 356887 359902 364916 367936 370943 372941 373937 374924 374907 375890 378881 386872 398848 402838 406828 416799 423777 430766 433760 438753 439744 442737 443732 443726 442719 0.50 493032 494027 493026 492023 490020 488019 487018 485019 484023 484024 484028 484033 485033 486037 488039 491039 492037 493032 493032 0.50 468240 467234 468227 471219 464216 452217 442219 436221 433224 430233 428236 425236 419236 413238 412242 417246 424247 429245 442244 446242 451243 463240 468240 0.50 468162 469158 467154 466153 465152 462152 460152 459152 456153 453155 453156 451159 452162 453163 455166 457168 457169 460172 463172 463169 466166 468162 0.50 445999 446995 445991 442987 435980 428975 422969 413964 410964 407968 406972 405977 406981 409988 415993 424994 430001 436003 442001 445999 0.50 338963 339959 338955 335950 326943 322942 315941 309943 304946 297956 293964 288974 288981 292986 296988 301990 307989 315987 320986 326983 331974 333970 338963 338963 1.00 425709 424702 421698 417696 410697 402706 396716 396719 398722 399726 396732 394741 394747 394754 395764 395777 395788 393799 393803 395805 399806 402802 407793 411781 413773 415762 419739 419730 420724 422719 425709 1.00 387829 386824 383820 377818 372817 369816 364817 360823 359831 359839 362850 365868 365878 366886 366889 368890 370887 371882 372875 373872 377869 381864 386856 385845 382842 385833 387829 1.00 330968 331961 329954 327952 323949 316946 311947 308949 302956 298964 295973 296979 299982 306985 317983 321983 325979 329971 330968 1.50 413717 412714 409711 407717 406721 405726 405733 405739 405744 407748 409747 411744 412739 412735 412726 412722 413717 1.50 407767 404765 403765 402770 401774 402778 404779 407777 408775 407771 407768 407767 1.50 380832 381828 379825 378824 375824 373823 371823 369821 368821 365821 364824 363826 363828 364831 365834 365838 367841 367842 369844 371844 374842 376839 377837 378836 380833 380832 1.50 327965 327960 325957 321953 313951 310952 306955 303959 300966 298973 301979 307981 314981 318981 322979 325975 327967 327965 2.00 377829 376829 373829 372832 374835 375834 377831 377829 2.00 324965 323962 320956 317956 311956 308958 305962 303966 302969 301975 305978 308979 314979 320978 322976 324969 324965 3.00 320969 318966 315964 314964 312963 309964 309965 308968 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