QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
559 PM EDT MON SEP 15 2008
 
 
FINAL DAY 1...DAY 2 AND DAY 3 QPF DISCUSSION
VALID SEP 16/0000 UTC THRU SEP 19/0000 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR
 
 
...DAY 1

UPDATED...LATER MODELS CONTD TO OFFER DIFFERING QPF SOLUTIONS FOR
RNFL ALONG THE FRONTAL BAND OVR THE SOUTHEAST.  MOST CHANGES FM
THE PRELIM TO THE FINAL DAY1 QPF WERE MADE TO ACCOUNT FOR LATEST
OBSERVATIONAL DATA.

...SYNOPSIS...
RELATIVELY DRY PD XPCTD OVR MUCH OF THE CONUS. STG MID/UPR LVL RDG
WL SLOLY PUSH ACRS THE WRN U.S. WHILE A DEEP MID/UPR TROF REMAINS
OVR THE ERN U.S.. FNTL BNDRY DRAPED ACRS THE SERN U.S. WL STALL
AND BCM A FOCUS FOR CNVCTN. SMALL...BUT WEAK CLSD LOW OFF THE PAC
CST WL MOV INLAND.

...SERN U.S....
FNTL BNDRY PUSHG ACRS THE REGION WL STALL AS THE UPR FLOW HAS BCM
SWRLY AND STGR HGT FALLS LIFT NEWD INTO SERN CANADA. MSTR REMAINS
DEEP ALNG THE BNDRY WITH SFC DWPTS IN THE 70S AND PWS 1.50-2.00
INCHES. SVRL WEAK MIDLVL SHRTWVS ARE SEEN IN THE GUID/WV SATL PICS
THAT WL RIDE OVR THE BNDRY AND SUPPORT PDS OF CNVCTN. MDLS ARE
SHOWG A LOT OF FEEDBACK...THAT IS MAKG THIS A DIFFICULT FCST.
ALTHOU THE PTNL FOR HVY RNFL WL EXIST...ORGANIZED HVY RNFL SEEMS
UNLKLY AS THE DEEP LYRD FOCUS/LIFT WL REMAIN RATHER WEAK. GNRLY
PAINTED A SWATH OF LGT/MOD PCPN AMTS FM SRN TX INTO THE LWR MS VLY
TO THE SRN MID ATLC REGION.

...FL...
WEAK SEA BREEZE CVRG COMBINED WITH SOME AFTN INSTBLTY/DEEP MSTR WL
SUPPORT DIURNAL CNVCTN.

...CA...
MIDLVL CLSD LOW APRCHG THE REGION WL BRING SOME COOLER MIDLVL
TEMPS THAT WL SUPPORT LIS DRPG BLO ZERO TUE AFTN. MSTR IS FCST TO
LIFT NWD TWD THE MIDLVL SYS AND HELP DESTABILIZE THE ATMOS. XPCT
AFTN/EVE CNVCTN OVR THE HIER TERRAIN AS DIFF HEATG HELPS GENERATE
POCKETS OF STGR LIFT. RNFL AMTS SHLD REMAIN LGT.
 
 
DAY 2 AND 3...


...SOUTHEAST AND ALONG THE MID ATLANTIC COAST...

A QUASI-STATIONARY FRONT ALONG THE MID-ATL COASTLINE INTO THE
SOUTHEAST WILL DELINEATE A VERY MOIST TROPICAL AIR MASS TO A MORE
SEASONABLE DRIER AIR MASS. AN APPROACHING UPSTREAM AMPLIFIED UPPER
TROUGH WILL HELP INDUCE AN AREA OF LOW PRESSURE NEAR THE NC/SWRN
VA COAST. THIS LOW SHOULD GET CAUGHT UP WITH THE UPPER TROUGH AND
SLIDE OFF TO THE NORTH AND EAST OR ALONG THIS BOUNDARY INTO THE
ATLANTIC. MOST OF THE MODEL GUIDANCE OF THIS FCST SCENARIO WITH
THE TRAILING SHEAR AXIS FUELING MORE DIURNAL CONVECTION AND HEAVY
RAINFALL ALONG THE COASTAL CAROLINAS INTO SERN GA AND THE FL
PENINSULA. BY DAY 3... THE UPPER SHEAR AXIS EXTENDING THROUGH THE
SOUTHEAST WILL GRADUALLY PRESS OFF THE SOUTHEAST COAST AND SETTLE
DOWN INTO THE FL PENINSULA. EXPECT ANOTHER DAILY ROUND OF
SCATTERED CONVECTION AND HEAVY RAINFALL WITH THE MOST CONCENTRATED
ACTIVITY ALONG OR JUST OFFSHORE OF THE SOUTHEAST COAST INTO FL.

...NEW ENGLAND...
A LARGE UPPER VORTEX OVER EXTREME NRN CANADA WILL SWEEP INTO ERN
CANADA DRIVING A STRONG COLD FRONT ACROSS THE COUNTRY INTO THE NEW
ENGLAND REGION. THIS FRONT APPEARS TO ARRIVE LATE DAY 2 INTO DAY 3
BUT DESPITE THE SHARP THERMAL GRADIENT AND DECENT VERTICAL LIFT...
LL MOISTURE/PW AVAILABILITY IS BASICALLY .75 OF AN INCH OR LESS.
THIS SHOULD BE ENOUGH FOR SOME SCATTERED SHOWERS SLIDING THROUGH
NEW ENGLAND WITH LOCALLY A .25 INCH OR LESS FOR RAINFALL AMOUNTS.

...WEST...
TWO FEATURES WILL ATTEMPT TO IMPACT THE WEST WITH POTENTIAL
RAINFALL BUT LIKELY QPF WILL BE MINIMAL TO NONE. A MID-LEVEL LOW
OVER NRN/CENTRAL CA AT THE BEGINNING OF DAY 2 WILL SHEAR-OUT INTO
THE NRN INTER-MOUNTAIN REGION AND ATTEMPT TO FUEL SOME SCATTERED
SHOWER ACTIVITY... AS SOMEWHAT MARGINAL MONSOONAL MOISTURE FROM
MEXICO ATTEMPTS TO SLIDE THROUGH THE SOUTHWEST AND INTERACT WITH
THE WEAKENING UPPER DYNAMICS. BY DAY 3... A SOLID CLOSED
UPPER-LEVEL LOW WILL SLIDE FROM THE ERN PAC TOWARD THE WEST COAST
POSSIBLY PRODUCING ENOUGH ONSHORE MOISTURE FETCH FOR SHOWER
ACTIVITY INTO NRN CA/SWRN OR COAST. THE MODEL GUIDANCE VARIES ON
THE SPEED OF THIS SYSTEM ARRIVING INTO THE WEST AND HPC GENERALLY
FOLLOWED THE MORE CONSISTENT ECMWF. 
     
ECKERT/MUSHER

GRAPHICS AVAILABLE ON THE WEB AT WWW.HPC.NCEP.NOAA.GOV
24HR QP VT 17/00Z
 0.01 423238 421235 417233 414231 410218 403213 400209 395206 
      392203 389204 393213 398217 404219 407225 405230 400227 
      397227 391229 388227 387231 393235 398238 400240 403240 
      409240 412241 416239 421239 423238 
 0.01 373750 370737 368732 365729 361728 355731 352735 350740 
      343754 339760 336767 334774 331781 329785 325790 320796 
      310809 307815 305820 306825 310827 309832 302833 298840 
      294847 291853 286866 286869 286875 284881 276897 264921 
      260927 255932 244945 237955 235962 233970 233978 234988 
      235994 238996 245999 248004 250004 258003 269996 271995 
      274992 276985 278979 278975 277970 274967 270962 270955 
      273941 279927 287911 294899 299885 301878 305873 313857 
      324846 331843 335842 338844 341846 347844 352839 354835 
      359830 364823 368816 371809 376795 378783 378776 377770 
      373750 
 0.01 370190 370189 370187 368183 366182 363182 360184 359184 
      359186 362188 363189 365190 367191 370190 370190 
 0.01 369050 364044 360040 355043 349045 345045 341048 339055 
      345058 352061 355062 357065 361069 361065 361057 366052 
      369050 
 0.01 343178 345175 344171 343168 342166 339166 336165 333163 
      331162 328162 325165 327167 330168 333169 336168 339169 
      339170 341174 343178 343179 343178 
 0.01 295814 290809 286807 279804 273803 262801 255801 252798 
      247803 244808 242813 242817 244821 248822 252818 253811 
      256813 261816 267818 272820 278820 286820 290819 294818 
      295816 295814 
 0.01 315016 314009 313006 310002 306004 303011 298020 293027 
      287033 285037 285039 288049 294054 299053 302049 304041 
      309033 312026 315016 
 0.25 363756 362751 359749 355753 345766 342771 340779 335792 
      335794 337800 339806 342808 346808 348815 351821 353821 
      363809 366802 369795 370787 370779 368774 365769 363760 
      363756 
 0.25 259969 259964 258960 256957 253955 249956 244960 241966 
      239972 239978 241986 243988 246988 251983 253979 257973 
      259969 
 0.50 366785 363785 361787 358788 357789 356790 353793 353795 
      353799 354802 355805 358806 360804 361803 362801 364797 
      366793 366789 366785 366785 
 0.50 349778 346780 344784 343789 345791 347792 348790 348786 
      349782 349780 349778 
 0.50 250974 251970 252967 250965 249964 246964 245965 244967 
      243969 242972 242974 242975 241978 242981 243983 246983 
      248980 249977 250974 250974  
 
24HR QP VT 18/00Z
 0.01 485680 484676 482677 477682 473686 469694 467700 465705 
      460717 452741 451747 450754 449768 450773 449782 449789 
      450795 450804 451812 453817 455820 459820 462817 464804 
      465790 469764 471750 474737 480710 482697 485684 485680 
 0.01 396716 394712 392709 388708 382708 376709 371711 364715 
      357719 352723 344732 336742 329754 323766 308782 290801 
      287802 283802 279802 270799 259799 252799 247801 244804 
      242809 238817 241821 245824 255826 265830 274832 286833 
      292835 296837 297840 297843 296849 298853 300855 304858 
      309861 315863 319861 321858 323853 326848 333847 341844 
      348840 354835 363826 369814 372812 379808 382805 383801 
      383794 383787 382784 378783 376779 377772 377766 376760 
      394737 396727 396716 
 0.01 436225 438222 438218 436213 432208 430205 427203 421200 
      416199 414203 415208 420211 426214 428215 432220 435225 
      436225 
 0.01 376792 376787 373786 371789 370790 369794 369795 369799 
      371800 373797 375793 376792 
 0.01 408187 407178 407173 409156 408152 407148 404142 400138 
      396135 390131 388127 393120 397117 403115 409114 414110 
      414106 413102 408102 404105 400106 395105 391107 387111 
      383112 376113 373117 369119 363118 351122 347124 340124 
      337126 333123 327122 324118 319108 316103 313099 309102 
      309109 307111 305111 301109 290104 286103 282104 282109 
      284113 289120 293123 300125 306126 311130 321144 323152 
      326157 333158 339157 342153 347152 351150 354145 364139 
      365140 369144 369151 365153 361155 363160 369162 374165 
      379170 384171 392175 396181 398185 402187 406188 408187 
 0.01 405061 403058 398057 392061 384062 375064 371063 367065 
      370068 370072 370077 372081 376086 379087 381086 384083 
      387082 391083 395079 398075 400070 401066 405061 
 0.01 374187 376184 374181 373180 372179 369177 366176 363178 
      366181 366182 368184 371186 373187 374187 374187 
 0.01 232977 236980 240981 247981 251979 256976 258972 262962 
      273943 279935 284926 289917 295909 300899 302892 303887 
      303883 300878 296876 292878 287882 284886 278894 273904 
      265913 259920 251926 244933 237940 233944 231949 
 0.01 286031 286026 285021 283019 278018 260017 254016 251012 
      248011 239011 234012 231014 231019 233023 236028 247036 
      252042 256048 263062 267067 271069 275069 275062 272053 
      272047 275041 280037 284034 286031 
 0.25 388729 387722 384719 375721 364725 354733 347739 342746 
      335755 331763 323778 314795 309802 303809 292814 287814 
      283812 276810 268810 260808 256809 254813 255815 257817 
      264819 272822 280824 288823 295827 302831 306833 309834 
      312832 321818 326816 331817 340818 345815 347812 351804 
      352799 352793 352788 353781 356774 361766 368757 373750 
      382740 386733 388729 
 0.25 254955 255952 254949 252946 246945 243948 240951 238955 
      237958 235963 235967 237970 239972 242971 247969 249967 
      251962 253958 254955 
 0.50 384727 381725 376725 371726 365729 355737 346745 341753 
      337762 335767 332772 326782 320801 318804 316809 317811 
      319811 322807 324803 326801 329801 337806 342805 344801 
      343788 343781 345777 351768 359760 365755 367752 369748 
      374743 380738 383734 384727 
 0.50 311817 310817 307817 305818 304820 305823 306823 306822 
      308821 311819 311817 
 1.00 376732 372732 369732 364734 359738 357741 352745 350748 
      348753 348756 350757 356754 361751 364747 367743 369740 
      374736 376732 
 1.50 365739 362739 360741 359743 361743 364742 365739 
 
 
24HR QP VT 19/00Z
 0.01 482683 478672 474665 470662 466662 458665 452670 444682 
      441690 439696 439701 442703 446702 447706 446711 443716 
      440722 439730 439738 436742 432748 431753 427769 425774 
      425778 426782 428784 431784 434781 438775 440772 443772 
      447776 452779 457778 463774 465768 466761 468747 470731 
      471723 473715 479703 481696 483688 482683 
 0.01 440260 442256 443252 441246 433240 422235 411231 406233 
      402232 394237 391240 389243 388247 395253 401257 406260 
      412262 417262 426263 435262 440260 
 0.01 457114 457109 456105 453100 447093 443090 437089 432089 
      430087 426085 424086 424091 424097 423100 418103 412102 
      410095 409093 406095 403097 400096 400093 401088 404085 
      407074 412067 413064 412061 408058 405056 400056 392058 
      384061 377062 374060 370058 367058 363060 363066 364069 
      369071 373081 376086 379087 385088 387091 391101 392106 
      390110 386112 382112 373116 366121 361130 358134 357139 
      361139 364135 368129 377131 383126 400120 403117 406118 
      413119 421116 438111 441114 442123 444127 446130 449128 
      451121 457114 
 0.01 375737 372732 367728 359723 353722 348723 345724 339726 
      332731 329735 324744 317754 311761 282793 272792 262794 
      250799 244801 242804 239809 237815 240821 244824 254823 
      262826 271832 276833 279836 282843 284846 288859 300881 
      303884 307886 310887 312885 315881 319877 325874 328870 
      326864 320853 318849 316842 318836 321832 329824 333815 
      340808 354788 358784 360779 363767 372751 374744 375737 
 0.01 411164 408160 404157 400156 394160 390164 384169 382171 
      381174 383181 388185 391183 390177 391172 396168 402165 
      411164 411164 
 0.25 363744 362737 357732 352731 347733 344736 338741 332748 
      328755 321768 307796 305799 300802 291806 276810 271810 
      268808 266804 264803 259804 255806 252808 251812 258818 
      262820 276824 284826 290829 293837 297846 299849 298852 
      301851 304846 307837 311831 320818 325813 331808 336804 
      338801 340793 342785 346779 363748 363744 
 0.50 358743 355737 350737 344740 339744 332753 327761 323771 
      319780 314790 311800 309804 309810 306815 301814 297813 
      293814 293817 294820 298824 303827 306823 308818 312814 
      322809 333803 335798 336793 338781 341776 344773 349763 
      355755 357750 358744 358743 
 1.00 345754 344751 342751 339754 333761 332766 329770 324779 
      321787 318795 319798 322798 325799 327796 329792 332784 
      335774 341768 344758 345754