Quantitative Precipitation Forecast
Issued by NWS

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727
FXUS04 KWBC 060852
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
351 AM EST SAT FEB 06 2016


PRELIM DAY 1...DAY 2 AND DAY 3 QPF DISCUSSION
VALID FEB 06/1200 UTC THRU FEB 09/1200 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR

...SOUTHEAST STATES...

AN IMPRESSIVE MID WINTER SHORTWAVE DIGS TO A LOW LATITUDE...WITH
500 MB HEIGHT ANOMALIES DOWN TO -2.5 STANDARD DEVIATIONS OVER
FLORIDA BY SUNDAY MORNING. CYCLOGENESIS OFFSHORE OF
FL/GA/SC...ALONG WITH AN INCREASINGLY DEEP UPPER SYSTEM WILL LEAD
TO STRONG ASCENT AND AN INFLUX OF MOISTURE...PRODUCING AN
ORGANIZED PRECIPITATION EVENT ACROSS THIS AREA. MODEL AGREEMENT IS
FAIRLY GOOD THROUGH EARLY DAY 2...AND THE QPF INHERITED FROM THE
PREVIOUS SHIFT PROVIDED A GOOD STARTING POINT. WE INCORPORATED
WHAT LITTLE TREND WAS OBSERVED TO THE QPF CONSENSUS ON THE 18-00Z
CYCLES...MAINLY A WESTWARD EXPANSION OF EACH ISOHYET BY ABOUT 30
MILES...CATCHING MORE OF SE GA WITH 0.10 TO 0.50 INCH AREAL
AVERAGE FOR THE 24-HOUR PERIOD. THE 00Z NAM DID APPEAR TO BE TOO
STRONG WITH THE SYSTEM AT AN EARLIER LEAD TIME...WHICH CAUSED ITS
DAY ONE OUTPUT TO PRODUCE MUCH MORE PRECIPITATION OVER SE GA INTO
COASTAL SC. WHILE THIS REGION SHOULD SEE THE MAXIMUM PRECIPITATION
AMOUNTS...GIVEN THEIR PLACEMENT IN THE DIFLUENT REGION NORTHEAST
OF THE UPPER LOW...THE MANUAL FORECAST IS MORE CONSERVATIVE THAN
THE NAM...BEING MORE IN LINE WITH THE GLOBAL CONSENSUS...THE
CANADIAN GEM REGIONAL MODEL...AND THE NAM CONUS NEST.

MEANWHILE...DOWN ACROSS SOUTH FLORIDA A REMNANT FRONTAL SYSTEM
WILL LIFT NORTHWARD FROM CUBA...BUT IS LIKELY TO REMAIN JUST
OUTSIDE OF THE STATE BEFORE LOW PRESSURE FORMS OFF THE SOUTHEAST
FL COAST AND LIFTS UP TOWARD THE CAROLINAS. AT THE SAME
TIME...HOWEVER...A SHARPLY DEFINED SURFACE TROUGH SHOULD FORM FROM
WEST OF NAPLES...CUTTING ACROSS SOUTH FLORIDA IN RESPONSE TO THE
INTENSE UPSTREAM HEIGHT FALLS. STEEPENING OF LAPSE RATES AND
STRONG SURFACE CONVERGENCE SHOULD BE SUFFICIENT TO FORM
THUNDERSTORMS DESPITE THE AREA BEING NORTH OF THE SYNOPTIC FRONT.
SOME SOLUTIONS SEEMED OVERDONE FOR MAGNITUDES GIVEN THE EVENT WILL
BE QUICKLY EVOLVING...BUT THERE WAS GOOD SPATIAL AGREEMENT TO THE
QPF FROM THE 12Z ECMWF...12Z WRF-NMM...AND 00Z NAM CONUS NEST.
THESE WERE BLENDED WITH THE PREVIOUS WPC FORECAST TO MAINTAIN
CONTINUITY.


...NORTHERN U.S. FROM MONTANA TO NORTHERN  NEW ENGLAND...

A SHARPLY DEFINED NORTHERN STREAM WAVE WILL DEEPEN AS IT ENTERS
THE NORTHERN PLAINS...WHERE HIGH WIND AND BLIZZARD WATCHES WERE IN
EFFECT. A DOWNSTREAM TROUGH WILL ALSO GRAZE THE GREAT LAKES AND
NORTHERN NEW ENGLAND. BOTH WEATHER SYSTEMS ARE WORKING WITH
RELATIVELY DRY AIR...BUT THERE IS AGREEABLE MODEL SIGNAL FOR AREAL
AVERAGE 0.10 INCH LIQUID FROM NORTHERN ND ACROSS NORTHERN MI TO
NORTHERN NY AND MAINE. THE SYSTEM ENTERING NORTH DAKOTA IS
PARTICULARLY DYNAMIC...SUCH THAT IT MAY SQUEEZE OUT AMOUNTS
GREATER THAN A QUARTER INCH THROUGH SUNDAY MORNING UP AROUND
BOTTINEAU AND NORTH OF DEVILS LAKE. THE PREVIOUS WPC FORECAST
PROVIDED A GOOD STARTING POINT...AND WE INCORPORATED SOME ASPECTS
OF THE GFS/ECMWF AND 18Z GEFS MEAN TO DEFINE THE SOUTHERN EXTENT
OF MEASURABLE PRECIPITATION AND EACH CATEGORY UP TO 0.25 INCH
AREAL AVERAGE. THE 00Z GEM REGIONAL AND SOME OF OUR IN-HOUSE
DOWNSCALED QPF TECHNIQUES WERE ALSO HELPFUL...AND LINED UP SUCH AS
TO INCREASE OUR CONFIDENCE.


...NORTHWEST / NORTHERN ROCKIES...

THE SHARP WAVE PASSING TOWARD THE NORTHERN PLAINS WILL PUSH A COLD
FRONT THROUGH THE NORTHWEST STATES AND NORTHERN ROCKIES. MOISTURE
IS IN LIMITED SUPPLY...BUT STRONG WESTERLY TO NORTHWESTERLY FLOW
WILL PAINT THE HIGHER TERRAIN WITH LIGHT ACCUMULATING
PRECIPITATION. MODEL FORECASTS AND OBSERVED PRECIP ASSOCIATED WITH
ANALOG EVENTS FROM THE GEFS REFORECAST DATABASE ARE WELL ALIGNED.
WE STARTED WITH THE PREVIOUS FORECAST AND MADE MINIMAL
CHANGES...INCORPORATING THE GEM REGIONAL AND NDFD FOR SOME OF THE
DETAILS.


...SOUTHERN PLAINS TOWARD THE WESTERN TO CENTRAL GULF COAST...

A STRONG MID LEVEL TROUGH CONTINUED TO DEEPEN AND DEVELOP TOWARD
HAVING A CLOSED CIRCULATION PER SATELLITE IMAGERY. THE SYSTEM WAS
SURROUNDED BY SUCH DRY AIR...HOWEVER...THAT WIDESPREAD RADAR
ECHOES APPARENTLY REPRESENTED MAINLY VIRGA...ALTHOUGH A FEW SITES
IN OK/TX HAD REGISTERED MEASURABLE PRECIPITATION AS OF 06Z. MODELS
CONTINUE TO AGREE THAT THE BEST LIKELIHOOD FOR ANY SIGNIFICANT
RAINFALL WOULD BE JUST EAST AND NORTHEAST OF THE TRACK OF THE MID
LEVEL LOW...ACROSS EASTERN TX. A SECOND SWATH OF PRECIPITATION
WILL FORM OFFSHORE IN THE GULF...WHILE MOST AREAS INLAND ACROSS
SOUTHEAST AND CENTRAL TEXAS SHOULD SEE ONLY A FEW HUNDREDTHS OF AN
INCH AS THE TROUGH PASSES QUICKLY THROUGH THE REGION EARLY TODAY.

DAYS 2/3...

...GREAT LAKES TO OH-TN VALLEYS/APPALACHIANS...

WIDESPREAD BUT GENERALLY LOW VALUES OF LIQUID EQUIVALENT ARE
EXPECTED TO DEVELOP IN ADVANCE OF THE LONGWAVE TROUGH POSITION
SUNDAY NIGHT INTO MONDAY AS A UPPER TROUGH EVOLVES INTO A CLOSED
MID/UPPER LEVEL LOW OVER THE OH VALLEY. GIVEN THE COMPLEXITY OF
THE SMALLER-SCALE AND SUBTLE RUN-TO-RUN VARIABILITY OF SOLUTIONS
EMBEDDED WITHIN THE TROUGH...A MODEL CONSENSUS WAS USED TO DERIVE
THE QPF. SINCE SOME PRECIPITATION WILL ALSO FALL AS SNOW...REFER
TO THE LATEST GUIDANCE FROM THE WPC WINTER WEATHER DESK FOR MORE
INFORMATION.


EAST COAST...

THE 06/00Z MODEL RUNS BACKED AWAY FROM THE SLIGHT WESTWARD SHIFT
THAT THEY MADE DURING THE 05/12Z PRODUCTION CYCLE.  AT FIRST...THE
REACTION WAS NOT TO MAKE TOO MUCH OF A MOVE AWAY FROM THE 05/12Z
ECMWF AND THE 06/00Z NAM WHICH CLUSTERED WELL.  THE CORRESPONDING
RUNS OF THE GFS AND UKMET WERE NOT AS AMPLIFIED AS THE
ECMWF/NAM...CONSEQUENTLY THEY TENDED TO MOVE THE FIRST WAVE OUT TO
SEA MORE QUICKLY.  THE QUESTION HAS BEEN WHETHER A SECOND
SHORTWAVE DROPPING IN FROM THE GREAT LAKES WOULD BE FORCED TO TAKE
A SOUTHERN TRACK IN THE EVENT THE FIRST WAVE WAS BLOCKING ITS
FORWARD PROGRESSION OR WHETHER THE FIRST WAVE WOULD BE OUT OF THE
WAY IN TIME TO ALLOW MORE AMPLIFICATION OF THE SECOND WAVE.  SINCE
THE OVERNIGHT RUN OF THE GEFS MEAN WAS FAIRLY CONSISTENT WITH ITS
PREVIOUS RUN...WE OPTED NOT TO MAKE ANY TOO MANY CHANGES IN THE
WPC FORECAST.  WITH THE MODELS HAVING A RATHER DIFFICULT TIME IN
HANDLING THE WAY THE MASS FIELDS INTERACT...IT FOLLOWS THAT THE
CONFIDENCE IN THE RESULTING QPF WAS BELOW AVERAGE.

REFER TO THE QPFHSD FOR MORE INFORMATION ON ANY WINTER WEATHER
WITH THIS SYSTEM.

GRAPHICS AVAILABLE ON THE WEB AT WWW.WPC.NCEP.NOAA.GOV

BANN


24HR QP VT 07/12Z
 0.01 532203 533193 532185 528172 525165 521160 514152 505145
      494138 486129 482125 477124 474122 476115 476111 475108
      470105 468103 466105 464111 464101 462094 460089 458084
      450073 446068 442067 436068 432073 436078 442080 446083
      450088 455093 458099 456102 455099 452095 447094 440095
      434094 430089 428106 429116 432118 436114 441117 445121
      446124 449124 452119 456116 461114 463113 463118 462121
      463124 455132 458132 458137 456146 455154 460157 464161
      470165 481163 490172 493176 496183 501188 505191 514198
      524206 529206 532203
 0.01 545987 539957 534944 530937 527929 518899 506872 495847
      489835 489830 490825 493816 497800 498793 499783 498775
      495768 496761 498755 499748 500744 500739 498732 494727
      493720 495712 496706 497701 497696 498691 501690 505686
      509681 511674 510666 507656 501640 494629 492625 490623
      489626 481637 477643 475649 465672 462681 458687 452698
      448712 448719 446725 440740 437746 435753 434769 430785
      426791 425796 424801 427798 433787 441777 445773 448767
      450760 451756 454754 449784 440813 448821 451826 451831
      450834 450839 448843 444848 440851 437858 436863 438866
      442866 444864 447864 447867 445872 444876 444882 445890
      450906 455918 462927 466931 467932 465935 457946 455963
      458968 462974 465979 467983 467987 468996 468006 471021
      475034 483064 485068 485074 486083 489097 491103 493112
      496117 501118 508110 512103 514097 515059 515053 516047
      519042 523039 527033 533022 540011 545987
 0.01 516262 518249 517243 514238 505221 501212 496205 492203
      487201 483203 481206 474209 465211 463213 458214 454218
      459226 467223 474221 484223 489225 492228 496237 498242
      495245 489239 485238 482241 478231 473234 472237 475242
      480248 485256 486261 484266 481269 477271 464278 460287
      457302 458307 461310 464312 469315 473316 477314 484311
      490307 497302 503296 507288 510282 512274 516262
 0.01 482095 482092 483090 481090 479092 481095 480097 482097
      482095
 0.01 452168 452166 450163 449160 448157 446155 445152 443149
      441149 439151 438153 437156 441157 442159 444162 445165
      448165 450168 452168
 0.01 429248 428241 423238 417237 412239 408241 405246 404252
      407256 413256 417254 422251 427249 429248
 0.01 446046 445043 445041 443038 441038 440040 441043 443045
      443046 444046 446046 446046
 0.01 426060 426058 425058 424060 425061 426061 426060
 0.01 415076 415073 413070 412068 414066 415066 416062 414061
      412063 409063 407065 405065 401067 405070 406070 408075
      410075 413076 415076
 0.01 406058 405058 404056 402055 402056 404058 405058 406058
 0.01 357741 356734 353732 345728 340726 335726 331726 327727
      322729 317730 313732 310737 303743 295748 278758 263769
      251782 242797 228833 227837 228841 236837 242843 250839
      257834 260832 267831 285825 287827 293828 303827 306832
      308834 311833 316827 326824 331823 336820 340818 344815
      350809 353799 350787 353776 353764 357741
 0.01 343965 343960 342955 339947 337943 335939 329934 323930
      316926 304918 294906 290899 287890 286886 286880 285869
      282860 278854 274853 270852 267851 263853 258858 255864
      248879 246888 245892 245897 250902 252905 253911 255931
      257939 260947 264966 266968 270970 275968 281969 286968
      289966 294962 299956 303954 308955 323961 334967 343965
 0.25 534000 534994 533987 528979 526976 523970 522966 522962
      523955 522948 518938 514929 512926 509924 508926 509929
      506929 507936 508942 510950 507948 504950 501949 497947
      497952 498957 502967 506975 511983 517990 522996 527005
      529006 532005 534000
 0.25 502278 503273 502270 498268 497276 494280 490284 485287
      481291 482295 485296 491297 495293 498288 501280 502278
 0.25 506006 505001 502994 499988 496982 492979 487981 485987
      485997 487003 491008 495010 501013 505012 506009 506006
 0.25 489142 489139 489138 488136 487135 486134 484136 485137
      486139 487140 488142 489142
 0.25 475845 473844 472843 471843 469843 469846 470847 471846
      473847 475845 475845
 0.25 350744 347743 343744 338745 334745 329744 325746 321745
      318742 316741 313743 308749 304755 297760 284768 272777
      261786 251796 244809 240816 238824 239828 243828 249823
      262816 267812 276809 285806 290807 292809 297813 305814
      314815 321817 328815 334810 339804 341797 343788 343778
      344768 345759 350744
 0.25 324949 323947 321945 319943 317942 316941 314941 313943
      314945 316947 317947 317948 319949 320949 321950 323952
      324949
 0.25 282941 281931 279924 278914 275908 271900 269898 266897
      264900 263905 264913 267921 270929 272935 273940 276942
      280943 282941
 0.50 341757 339755 335755 328759 318770 311774 307774 305771
      311756 313749 311750 308753 304760 299766 288775 282779
      276783 263791 257795 254802 251809 246815 245819 247821
      253816 258813 264807 278801 284797 288797 292799 302810
      317809 324811 328810 331808 336802 338794 339785 339775
      338769 339763 341757
 1.00 332776 332770 329767 322772 316779 311784 304791 301798
      302802 305805 314801 321797 328791 330787 331783 332776
 1.50 327781 326778 324776 319780 316784 313788 310792 307799
      309801 313798 317795 321791 325786 327781
 2.00 315792 315791 315792 315792

24HR QP VT 08/12Z
 0.01 534193 534188 533184 529178 520165 515158 511153 508150
      504149 499149 491146 489149 490152 492155 496157 498160
      498163 492167 491168 492171 499176 505177 509177 512180
      515186 524200 526203 530203 532201 534195 534193
 0.01 520258 521253 520251 516246 512239 509227 503220 496212
      488210 485212 485216 484223 485226 482226 479226 472234
      472238 470240 469243 475245 478247 478251 473259 466267
      463274 465280 468283 473286 476289 481291 486291 489291
      493290 502286 508280 513271 518261 520258
 0.01 528952 525925 526920 526911 526904 525898 522878 520870
      519865 518861 517857 516853 510830 510823 508818 506814
      503809 495797 489791 484783 482779 479775 474770 466768
      458763 452765 449773 448785 445787 442788 405803 389810
      377818 369824 363829 358835 356839 353843 350849 349852
      349858 350864 351866 355870 358872 357877 357885 359888
      362890 370889 379884 393875 403865 407867 410872 405878
      400885 397890 396896 396906 396913 397917 398926 400929
      400932 402933 413947 426960 428964 431964 436969 443973
      445976 449978 456984 462989 469995 471999 471003 470006
      468010 468014 469021 471024 474028 476029 484030 494031
      501026 506019 508016 511010 513003 515999 515993 522973
      526960 528952
 0.01 507685 505667 503655 498643 492637 488635 483635 479637
      477641 468661 465665 463670 459679 455688 455692 454695
      454700 453715 454725 456727 459726 465725 471718 473714
      476710 482703 486699 491701 494702 499701 505694 507685
 0.01 488136 487136 486133 484132 483132 481132 479131 478131
      476129 474128 473128 474131 476132 478132 479133 481133
      482133 484136 486136 487137 488136
 0.01 438859 438856 436855 434857 433857 431859 431860 429860
      428862 429864 431866 433866 434864 435863 436861 438859
 0.01 417693 416684 413679 408675 403673 390675 381674 368674
      362673 355676 351677 346681 338687 319703 302716 291721
      280728 272734 268738 265742 258750 251760 249764 247769
      248773 251776 259775 263772 267769 271767 275767 282772
      290779 294784 297790 306795 315800 320802 325803 337805
      344803 350800 357793 360783 362768 364762 368757 371754
      378751 386747 396739 401735 405730 411721 414710 416700
      417693
 0.25 511257 511250 508245 503246 498247 493248 490252 487259
      485264 486268 489270 493269 497268 501264 506261 509262
      511260 511257
 0.25 493939 493932 492925 491914 491899 491886 489874 486864
      480857 475854 472857 472862 472869 470873 466893 463903
      461907 461913 462925 466932 470942 474948 477951 481952
      487951 491945 493939
 0.25 474825 472816 469809 466806 462805 456806 449809 446812
      447817 452821 456822 458825 462830 469833 473830 474825
 0.25 402701 402694 399692 395690 391690 378685 371683 361683
      354686 348690 341696 335702 325713 314726 309732 304736
      294739 288744 284749 285754 287757 296771 305782 311788
      318793 324795 332796 341794 344792 347787 350780 352773
      356764 360758 365753 372747 393725 397719 400713 402706
      402701
 0.50 398709 398703 397698 394696 390697 383696 377694 371691
      365689 358690 351693 340702 331712 322724 314734 306745
      303751 301757 301763 303768 307774 310779 314783 320788
      326791 334791 341788 353762 357756 362751 366746 371742
      383732 391723 396715 398709
 1.00 393711 392706 390706 382708 377710 374707 369704 363703
      353700 347703 342708 335714 327725 321733 315744 311755
      310759 311763 313770 319778 324782 330784 336783 340779
      351758 358748 364740 369736 377733 384726 390718 393711
 1.50 387717 386713 383714 378717 372720 367719 363717 359713
      351711 345712 340715 334721 328731 323739 319749 317760
      318766 320771 323775 326777 332778 336777 340774 343770
      352751 357742 360737 363733 368731 371730 373731 380727
      385721 387717
 2.00 356732 356727 354724 350721 344721 340724 332732 326742
      324748 323754 321761 324769 327773 332774 337772 342768
      347758 352746 355735 356732
 3.00 345752 345745 343741 338741 335743 332748 331752 330757
      328760 328766 331768 336768 340764 341762 344757 345752
      345752

24HR QP VT 09/12Z
 0.01 512037 511032 508027 505022 501020 495020 491017 488012
      485009 482004 478002 476001 473999 472999 470001 473011
      479019 486027 487033 491036 495038 500040 510040 512037
 0.01 504860 503842 502826 495815 493812 493807 492798 486786
      484781 481777 478772 475768 471764 467761 452750 446748
      442745 440742 441739 444735 447706 449700 453697 457694
      462689 464683 465678 463666 459648 457640 454634 450630
      446631 436634 425652 421657 415659 405663 399667 393670
      388673 384677 362688 356696 353699 347700 343699 341703
      334710 326719 319727 311735 304744 300747 298752 293761
      286780 283787 280792 277797 276802 276809 280812 290816
      298820 292828 286835 282839 283845 284853 287859 292870
      297880 301883 305885 309886 312884 323877 330872 337865
      340862 344864 348866 351872 354878 357883 361885 368885
      370885 372888 373906 375913 377916 378918 382918 386918
      389913 392911 396906 401901 411897 417896 421898 430906
      434910 438911 444914 448918 452920 455925 460932 462935
      466936 471937 480932 487922 490912 490894 495889 497883
      501870 504860
 0.01 361765 360760 358758 353758 350759 348762 343766 338771
      335776 329787 322799 321802 322805 326810 332813 337815
      341811 345805 356799 357797 355795 352795 351786 350782
      352780 357774 361765
 0.25 481864 473845 470835 469821 467810 461802 454797 446795
      430792 421790 412790 403791 397793 393796 388802 383803
      379805 374811 371815 366817 361825 360829 360832 365833
      368835 371838 375839 381840 385838 390831 392827 394825
      398822 402823 407824 410828 417832 423836 431838 443839
      450840 454840 458841 461845 462851 462878 464889 466895
      468898 472897 475893 478884 480873 481864
 0.25 451676 452668 451661 447655 443654 440654 437656 432659
      425664 416669 405675 394681 391684 387688 383697 379700
      375701 356706 348712 340720 333728 328736 317752 312762
      309766 305769 303773 302777 303785 306790 310790 314787
      321780 334765 347751 359735 365733 368729 379729 387732
      398733 404733 409730 416724 424718 428714 431710 437700
      443692 448684 451676
 0.50 442672 441668 439666 434667 431669 418675 405682 399686
      395690 391696 390703 389712 391717 394719 400718 406717
      413713 417709 423705 427700 436689 439683 441676 442672
 0.50 359720 359716 357714 350718 345721 340727 335732 331739
      328746 326753 322759 318765 314770 313774 314779 316779
      319776 323771 326764 327761 330759 337756 341750 350738
      358725 359720

$$





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